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Reflections on the Decline of Science in England, and on Some of Its Causes by Charles Babbage, is part of the HackerNoon Books Series. You can jump to any chapter in this book . Conclusion here CONCLUSION. In a work on the Decline of Science, at a period when England has so recently lost two of its brightest ornaments, I should hardly be excused if I omitted to devote a few words to the names of Wollaston and of Davy. Until the warm feelings of surviving kindred and admiring friends shall be cold as the grave from which remembrance vainly recalls their cherished forms, invested with all the life and energy of recent existence, the volumes of their biography must be sealed. Their contemporaries can expect only to read their eloge. In habits of intercourse with both those distinguished individuals, sufficiently frequent to mark the curiously different structure of their minds, I was yet not on such terms even with him I most esteemed, as to view his great qualities through that medium which is rarely penetrated by the eyes of long and very intimate friendship. Caution and precision were the predominant features of the character of Wollaston, and those who are disposed to reduce the number of principles, would perhaps justly trace the precision which adorned his philosophical, to the extreme caution which pervaded his moral character. It may indeed be questioned whether the latter quality will not in all persons of great abilities produce the former. Ambition constituted a far larger ingredient in the character of Davy, and with the daring hand of genius he grasped even the remotest conclusions to which a theory led him. He seemed to think invention a more common attribute than it really is, and hastened, as soon as he was in possession of a new fact or a new principle, to communicate it to the world, doubtful perhaps lest he might not be anticipated; but, confident in his own powers, he was content to give to others a chance of reaping some part of that harvest, the largest portion of which he knew must still fall to his own share. Dr. Wollaston, on the other hand, appreciated more truly the rarity of the inventive faculty; and, undeterred by the fear of being anticipated, when he had contrived a new instrument, or detected a new principle, he brought all the information that he could collect from others, or which arose from his own reflection, to bear upon it for years, before he delivered it to the world. The most singular characteristic of Wollaston's mind was the plain and distinct line which separated what he knew from what he did not know; and this again, arising from his precision, might be traced to caution. It would, however, have been visible to such an extent in few except himself, for there were very few so perfectly free from vanity and affectation. To this circumstance may be attributed a peculiarity of manner in the mode in which he communicated information to those who sought it from him, which was to many extremely disagreeable. He usually, by a few questions, ascertained precisely how much the inquirer knew upon the subject, or the exact point at which his ignorance commenced, a process not very agreeable to the vanity of mankind; taking up the subject at this point, he would then very clearly and shortly explain it. His acquaintance with mathematics was very limited. Many years since, when I was an unsuccessful candidate for a professorship of mathematics, I applied to Dr. W. for a recommendation; he declined it, on the ground of its not being his pursuit. I told him I asked it, because I thought it would have weight, to which he replied, that it ought to have none whatever. There is no doubt his view was the just one. Yet such is the state of ignorance which exists on these subjects, that I have several times heard him mentioned as one of the greatest mathematicians of the age. [This of course could only have happened in England.] But in this as in all other points, the precision with which he comprehended and retained all he had ever learned, especially of the elementary applications of mathematics to physics, was such, that he possessed greater command over those subjects than many of far more extensive knowledge. In associating with Wollaston, you perceived that the predominant principle was to avoid error; in the society of Davy, you saw that it was the desire to see and make known truth. Wollaston never could have been a poet; Davy might have been a great one. A question which I put, successively, to each of these distinguished philosophers, will show how very differently a subject may be viewed by minds even of the highest order. About the time Mr. Perkins was making his experiments on the compression of water, I was much struck with the mechanical means he had brought to bear on the subject, and was speculating on other applications of it, which I will presently mention. Meeting Dr. Wollaston one morning in the shop of a bookseller, I proposed this question: If two volumes of hydrogen and one of oxygen are mixed together in a vessel, and if by mechanical pressure they can be so condensed as to become of the same specific gravity as water, will the gases under these circumstances unite and form water? "What do you think they will do?" said Dr. W. I replied, that I should rather expect they would unite. "I see no reason to suppose it," said he. I then inquired whether he thought the experiment worth making. He answered, that he did not, for that he should think it would certainly not succeed. A few days after, I proposed the same question to Sir Humphry Davy. He at once said, "they will become water, of course;" and on my inquiring whether he thought the experiment worth making, he observed that it was a good experiment, but one which it was hardly necessary to make, as it must succeed. These were off-hand answers, which it might perhaps be hardly fair to have recorded, had they been of persons of less eminent talent: and it adds to the curiosity of the circumstance to mention, that I believe Dr. Wollaston's reason for supposing no union would take place, arose from the nature of the electrical relations of the two gases remaining unchanged, an objection which did not weigh with the philosopher whose discoveries had given birth to it. [The result of the experiment appeared, and still appears to me, to be of the highest importance; and I will shortly state the views with which it was connected. The next great discovery in chemistry to definite proportions, will be to find means of forming all the simple unions of one atom with one, with two, or with more of say other substance: and it occurred to me that the gaseous bodies presented the fairest chance of success; and that if wishing, for instance, to unite four atoms of one substance with one of another, we could, by mechanical means, reduce the mixed gases to the same specific gravity as the substance would possess which resulted from their union, then either that such union would actually take place, or the particles of the two substances would be most favourably situated for the action of caloric, electricity, or other causes, to produce the combination. It would indeed seem to follow, that if combination should take place under such circumstances, then the most probable proportion in which the atoms would unite, should be that which furnished a fluid of the least specific gravity: but until the experiments are made, it is by no means certain that other combinations might not be produced.] The singular minuteness of the particles of bodies submitted by Dr. Wollaston to chemical analysis, has excited the admiration of all those who have had the good fortune to witness his experiments; and the methods he employed deserve to be much more widely known. It appears to me that a great mistake exists on the subject. It has been adduced as one of those facts which prove the extraordinary acuteness of the bodily senses of the individual,—a circumstance which, if it were true, would add but little to his philosophical character; I am, however, inclined to view it in a far different light, and to see in it one of the natural results of the admirable precision of his knowledge. During the many opportunities I have enjoyed of seeing his minute experiments, I remember but one instance in which I noticed any remarkable difference in the acuteness of his bodily faculties, either of his hearing, his sight, or of his sense of smell, from those of other persons who possessed them in a good degree. [This was at Mr. South's observatory, and the object was, the dots on the declination circle of his equatorial; but, in this instance, Dr. Wollaston did not attempt to TEACH ME HOW TO SEE THEM.] He never showed me an almost microscopic wire, which was visible to his, and invisible to my own eye: even in the beautiful experiments he made relative to sounds inaudible to certain ears, he never produced a tone which was unheard by mine, although sensible to his ear; and I believe this will be found to have been the case by most of those whose minds had been much accustomed to experimental inquiries, and who possessed their faculties unimpaired by illness or by age. It was a much more valuable property on which the success of such inquiries depended. It arose from the perfect attention which he could command, and the minute precision with which he examined every object. A striking illustration of the fact that an object is frequently not seen, FROM NOT KNOWING HOW TO SEE IT, rather than from any defect in the organ of vision, occurred to me some years since, when on a visit at Slough. Conversing with Mr. Herschel on the dark lines seen in the solar spectrum by Fraunhofer, he inquired whether I had seen them; and on my replying in the negative, and expressing a great desire to see them, he mentioned the extreme difficulty he had had, even with Fraunhofer's description in his hand and the long time which it had cost him in detecting them. My friend then added, "I will prepare the apparatus, and put you in such a position that they shall be visible, and yet you shall look for them and not find them: after which, while you remain in the same position, I will instruct you how to see them, and you shall see them, and not merely wonder you did not see them before, but you shall find it impossible to look at the spectrum without seeing them." On looking as I was directed, notwithstanding the previous warning, I did not see them; and after some time I inquired how they might be seen, when the prediction of Mr. Herschel was completely fulfilled. It was this attention to minute phenomena which Dr. Wollaston applied with such powerful effect to chemistry. In the ordinary cases of precipitation the cloudiness is visible in a single drop as well as in a gallon of a solution; and in those cases where the cloudiness is so slight, as to require a mass of fluid to render it visible, previous evaporation, quickly performed on slips of window glass, rendered the solution more concentrated. The true value of this minute chemistry arises from its cheapness and the extreme rapidity with which it can be accomplished: it may, in hands like those of Wollaston, be used for discovery, but not for measure. I have thought it more necessary to place this subject on what I consider its true grounds, for two reasons. In the first place, I feel that injustice has been done to a distinguished philosopher in attributing to some of his bodily senses that excellence which I think is proved to have depended on the admirable training of his intellectual faculties. And, in the next place, if I have established the fact, whilst it affords us better means of judging of such observations as lay claim to an accuracy "MORE THAN HUMAN," it also opens, to the patient inquirer into truth, a path by which he may acquire powers that he would otherwise have thought were only the gift of nature to a favoured few. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Charles Babbage (1998).Reflections on the Decline of Science in England, and on Some of Its Causes. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/1216/pg1216-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at www.gutenberg.org https://www.gutenberg.org/policy/license.html

When England has so recently lost two of its brightest ornaments

Scientific American, Volume XXXVI., No. 8, February 24, 1877 by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . Natural Ornaments in Winter. here Natural Ornaments in Winter. Now that the hedges are no longer green, and the trees stand black and bare on the landscape, is the time to seek for endless variety and beauty waiting to be admired in its turn. What miniature fairy glens and grottoes are distributed over the hedge banks of our country lanes! Mosses, delicate and beautiful, may be found in the interstices of any old wall, or at the foot of almost any tree or shrub. In the winter time mosses and lichens are found in fruit, and are beautiful objects. A pocket microscope lens is essential for their proper observation; and though the delicate carmine cups of the species known as the cup moss, and the familiar gray and yellow mosaic appearance we see on twigs and branches on our way, are easily recognized, the study of this form of winter vegetation is an inexhaustible one, and is an occupation for a lifetime, if earnestly pursued. We do not however, suggest that every one who endeavors to recognize the different species of moss, lichens, or fungi should necessarily do so through the medium of the microscope; but it will greatly add to the pleasure of making a collection out of doors if there be a good microscope at home, so that when the contents of the basket be turned out, after the winter's walk, there should be interest even in the fragments left, after a little pile of varied bits has been constructed, rivalling the choicest summer bouquet in beauty of form and color. We have seen such a collection formed into a beautiful object by raising a little mound of rough bits of bark in a plate or saucer, and placing on it varieties of fungus of every shade of red, brown, yellow, and gray. They seem to spring forth from a bed of sphagnum or bog moss of brightest emerald green; while a clump of the screw wall moss in fruit, with its curious little box-like capsules, supports a gray or yellow lichen, which has been gently removed from some old wall or tree. A bit of stick or a twig, incrusted with a bright orange-colored lichen, supports a trailing branch of delicate green ivy, the most beautiful and adaptable of all winter foliage. Over this little arrangement is placed a bell glass, to preserve it from dust and the effect of a dry atmosphere; and we know how pleasing to the eye is its varied beauty of form and color, lasting thus, a constant source of pleasure, for many a day without renewal.— . Chambers' Journal About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Various (2006). Scientific American, Volume XXXVI., No. 8, February 24, 1877. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/19406/pg19406-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at www.gutenberg.org https://www.gutenberg.org/policy/license.html

Natural Ornaments in Winter

PLANTS continued—FRUITS—ORNAMENTAL TREES—FLOWERS.

Building a User-Friendly Interface for Central Bank Digital Currency Applications: A Case Study 

This paper is available on arxiv under CC 4.0 license.
Authors:
(1) Falke B. Ø. Carlsen, Department of Computer Science, Aalborg University, Denmark & falkeboc@cs.aau.dk;
(2) Lars Bo P. Frydenskov, Department of Computer Science, Aalborg University, Denmark & larsbopark@gmail.com;
(3) Nicolaj Ø. Jensen, Department of Computer Science, Aalborg University, Denmark & noje@cs.aau.dk;
(4) Jener Rasmussen, jener@jener.dk;
(5) Mathias M. Sørensen, mathiasmehlsoerensen@gmail.com;
(6) Asger G. Weirsøe, asger@weircon.dk;
(7) Mathias C. Jensen, Department of Computer Science, Aalborg University, Denmark & mcje@cs.aau.dk;
(8) Kim G. Larsen, Department of Computer Science, Aalborg University, Denmark & kgl@cs.aau.dk. Table of Links Introduction Definitions Model Checking Tool Overview Evaluation Conclusion and References 6 Conclusion In this paper, we present CGAAL, our model checker of alternating-time temporal logic properties in concurrent games. CGAAL checks such properties by encoding the problem as an extended dependency graph and then computes the satisfaction relation using the distributed local on-the-fly CERTAINZERO algorithm by Dalsgaard et al. [4]. We provide multiple novel search strategies for the algorithm and allow concurrent games to be expressed in our language LCGS. Our experiments show that the local on the-fly algorithm outperforms the global algorithm in the majority of cases. We also find that CGAAL outperforms the state-of-the-art tool PRISM-games by being up to two orders of magnitude faster, especially in models where synchronisations affect the internal state of modules and whenever we are not required to compute the entire fixed point. However, this comparison is unfair, since our test only uses a fraction of PRISM-games feature set. CGAAL is still in early development and much work is needed before it competes with PRISM in terms of capabilities. However, dependency graphs have been used for encoding various model checking problems, and we intend to incorporate these techniques into CGAAL. References [1] Rajeev Alur, Thomas A. Henzinger & Orna Kupferman (2002): Alternating-Time Temporal Logic. J. ACM 49(5), p. 672–713, doi:10.1145/585265.585270. [2] Edmund M. Clarke & E. Allen Emerson (1982): Design and synthesis of synchronization skeletons using branching time temporal logic. In Dexter Kozen, editor: Logics of Programs, Springer Berlin Heidelberg, Berlin, Heidelberg, pp. 52–71, doi:10.1007/BFb0025774. [3] Edmund M Clarke, Thomas A Henzinger, Helmut Veith, Roderick Bloem et al. (2018): Handbook of model checking. 10, Springer, doi:10.1007/978-3-319-10575-8. [4] Dalsgaard, Andreas E. and Enevoldsen, Søren and Fogh, Peter and Jensen, Lasse S. and Jepsen, Tobias S. and Kaufmann, Isabella and Larsen, Kim G. and Nielsen, Søren M. and Olesen, Mads Chr. and Pastva, Samuel and Srba, Jiˇrí (2017): Extended Dependency Graphs and Efficient Distributed Fixed-Point Computation. In Wil van der Aalst & Eike Best, editors: Application and Theory of Petri Nets and Concurrency, Springer International Publishing, Cham, pp. 139–158, doi:10.1007/978-3-319-57861-3_10. [5] Søren Enevoldsen, Mathias Claus Jensen, Kim Guldstrand Larsen, Anders Mariegaard & Jiˇrí Srba (2020): Verification of Multiplayer Stochastic Games via Abstract Dependency Graphs. LOPSTR2020, doi:10.1007/978-3-030-68446-4_13. [6] Søren Enevoldsen, Kim Guldstrand Larsen & Jirí Srba (2022): Extended abstract dependency graphs. Int. J. Softw. Tools Technol. Transf. 24(1), pp. 49–65, doi:10.1007/s10009-021-00638-8. [7] Glen Jeh & Jennifer Widom (2002): SimRank: a measure of structural-context similarity. In: Proceedings of the Eighth ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, July 23-26, 2002, Edmonton, Alberta, Canada, ACM, pp. 538–543, doi:10.1145/775047.775126. [8] Jonas F. Jensen, Thomas Nielsen, Lars K. Oestergaard & Jiˇrí Srba (2016): TAPAAL and Reachability Analysis of P/T Nets, pp. 307–318. Springer Berlin Heidelberg, Berlin, Heidelberg, doi:10.1007/978-3-662-53401-4_16. [9] Jonas Finnemann Jensen, Kim Guldstrand Larsen, Jiri Srba & Lars Kaerlund Østergaard (2016): Efficient model-checking of weighted CTL with upper-bound constraints. International Journal on Software Tools for Technology Transfer 18(4), pp. 409–426, doi:10.1007/s10009-014-0359-5. [10] Mathias Claus Jensen, Anders Mariegaard & Kim Guldstrand Larsen (2019): Symbolic model checking of weighted PCTL using dependency graphs. NASA Formal Methods Symposium, pp. 298–315, doi:10.1007/978-3-030-20652-9_20. [11] M. Kwiatkowska, G. Norman & D. Parker (2011): PRISM 4.0: Verification of Probabilistic Real-time Systems. In G. Gopalakrishnan & S. Qadeer, editors: Proc. 23rd International Conference on Computer Aided Verification (CAV’11), LNCS 6806, Springer, pp. 585–591, doi:10.1007/978-3-642-22110-1_47. [12] M. Kwiatkowska, G. Norman, D. Parker & G. Santos (2020): PRISM-games 3.0: Stochastic Game Verification with Concurrency, Equilibria and Time. In: Proc. 32nd International Conference on Computer Aided Verification (CAV’20), LNCS 12225, Springer, pp. 475–487, doi:10.1007/978-3-030-53291-8_25. [13] Sangkeun Lee, Minsuk Kahng & Sang goo Lee (2015): Constructing compact and effective graphs for recommender systems via node and edge aggregations. Expert Systems with Applications 42(7), pp. 3396–3409, doi:10.1016/j.eswa.2014.11.062. [14] Xinxin Liu & Scott A. Smolka (1998): Simple Linear-Time Algorithms for Minimal Fixed Points (Extended Abstract). In Kim Guldstrand Larsen, Sven Skyum & Glynn Winskel, editors: Automata, Languages and Programming, 25th International Colloquium, ICALP’98, Aalborg, Denmark, July 13-17, 1998, Proceedings, Lecture Notes in Computer Science 1443, Springer, pp. 53–66, doi:10.1007/BFb0055040. [15] Lawrence Page, Sergey Brin, Rajeev Motwani & Terry Winograd (1998): The PageRank Citation Ranking: Bringing Order to the Web. Technical Report, Stanford Digital Library Technologies Project. Available at http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.31.1768. This paper is available on Arxiv under CC 4.0 license. This paper is available on arxiv under CC 4.0 license. Authors: (1) Falke B. Ø. Carlsen, Department of Computer Science, Aalborg University, Denmark & falkeboc@cs.aau.dk; (2) Lars Bo P. Frydenskov, Department of Computer Science, Aalborg University, Denmark & larsbopark@gmail.com; (3) Nicolaj Ø. Jensen, Department of Computer Science, Aalborg University, Denmark & noje@cs.aau.dk; (4) Jener Rasmussen, jener@jener.dk; (5) Mathias M. Sørensen, mathiasmehlsoerensen@gmail.com; (6) Asger G. Weirsøe, asger@weircon.dk; (7) Mathias C. Jensen, Department of Computer Science, Aalborg University, Denmark & mcje@cs.aau.dk; (8) Kim G. Larsen, Department of Computer Science, Aalborg University, Denmark & kgl@cs.aau.dk. This paper is available on arxiv under CC 4.0 license. Authors: Authors: (1) Falke B. Ø. Carlsen, Department of Computer Science, Aalborg University, Denmark & falkeboc@cs.aau.dk; (2) Lars Bo P. Frydenskov, Department of Computer Science, Aalborg University, Denmark & larsbopark@gmail.com; (3) Nicolaj Ø. Jensen, Department of Computer Science, Aalborg University, Denmark & noje@cs.aau.dk; (4) Jener Rasmussen, jener@jener.dk; (5) Mathias M. Sørensen, mathiasmehlsoerensen@gmail.com; (6) Asger G. Weirsøe, asger@weircon.dk; (7) Mathias C. Jensen, Department of Computer Science, Aalborg University, Denmark & mcje@cs.aau.dk; (8) Kim G. Larsen, Department of Computer Science, Aalborg University, Denmark & kgl@cs.aau.dk. Table of Links Introduction Introduction Definitions Definitions Model Checking Model Checking Tool Overview Tool Overview Evaluation Evaluation Conclusion and References Conclusion and References 6 Conclusion In this paper, we present CGAAL, our model checker of alternating-time temporal logic properties in concurrent games. CGAAL checks such properties by encoding the problem as an extended dependency graph and then computes the satisfaction relation using the distributed local on-the-fly CERTAINZERO algorithm by Dalsgaard et al. [4]. We provide multiple novel search strategies for the algorithm and allow concurrent games to be expressed in our language LCGS. Our experiments show that the local on the-fly algorithm outperforms the global algorithm in the majority of cases. We also find that CGAAL outperforms the state-of-the-art tool PRISM-games by being up to two orders of magnitude faster, especially in models where synchronisations affect the internal state of modules and whenever we are not required to compute the entire fixed point. However, this comparison is unfair, since our test only uses a fraction of PRISM-games feature set. CGAAL is still in early development and much work is needed before it competes with PRISM in terms of capabilities. However, dependency graphs have been used for encoding various model checking problems, and we intend to incorporate these techniques into CGAAL. References [1] Rajeev Alur, Thomas A. Henzinger & Orna Kupferman (2002): Alternating-Time Temporal Logic. J. ACM 49(5), p. 672–713, doi:10.1145/585265.585270. [2] Edmund M. Clarke & E. Allen Emerson (1982): Design and synthesis of synchronization skeletons using branching time temporal logic. In Dexter Kozen, editor: Logics of Programs, Springer Berlin Heidelberg, Berlin, Heidelberg, pp. 52–71, doi:10.1007/BFb0025774. [3] Edmund M Clarke, Thomas A Henzinger, Helmut Veith, Roderick Bloem et al. (2018): Handbook of model checking. 10, Springer, doi:10.1007/978-3-319-10575-8. [4] Dalsgaard, Andreas E. and Enevoldsen, Søren and Fogh, Peter and Jensen, Lasse S. and Jepsen, Tobias S. and Kaufmann, Isabella and Larsen, Kim G. and Nielsen, Søren M. and Olesen, Mads Chr. and Pastva, Samuel and Srba, Jiˇrí (2017): Extended Dependency Graphs and Efficient Distributed Fixed-Point Computation. In Wil van der Aalst & Eike Best, editors: Application and Theory of Petri Nets and Concurrency, Springer International Publishing, Cham, pp. 139–158, doi:10.1007/978-3-319-57861-3_10. [5] Søren Enevoldsen, Mathias Claus Jensen, Kim Guldstrand Larsen, Anders Mariegaard & Jiˇrí Srba (2020): Verification of Multiplayer Stochastic Games via Abstract Dependency Graphs. LOPSTR2020, doi:10.1007/978-3-030-68446-4_13. [6] Søren Enevoldsen, Kim Guldstrand Larsen & Jirí Srba (2022): Extended abstract dependency graphs. Int. J. Softw. Tools Technol. Transf. 24(1), pp. 49–65, doi:10.1007/s10009-021-00638-8. [7] Glen Jeh & Jennifer Widom (2002): SimRank: a measure of structural-context similarity. In: Proceedings of the Eighth ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, July 23-26, 2002, Edmonton, Alberta, Canada, ACM, pp. 538–543, doi:10.1145/775047.775126. [8] Jonas F. Jensen, Thomas Nielsen, Lars K. Oestergaard & Jiˇrí Srba (2016): TAPAAL and Reachability Analysis of P/T Nets, pp. 307–318. Springer Berlin Heidelberg, Berlin, Heidelberg, doi:10.1007/978-3-662-53401-4_16. [9] Jonas Finnemann Jensen, Kim Guldstrand Larsen, Jiri Srba & Lars Kaerlund Østergaard (2016): Efficient model-checking of weighted CTL with upper-bound constraints. International Journal on Software Tools for Technology Transfer 18(4), pp. 409–426, doi:10.1007/s10009-014-0359-5. [10] Mathias Claus Jensen, Anders Mariegaard & Kim Guldstrand Larsen (2019): Symbolic model checking of weighted PCTL using dependency graphs. NASA Formal Methods Symposium, pp. 298–315, doi:10.1007/978-3-030-20652-9_20. [11] M. Kwiatkowska, G. Norman & D. Parker (2011): PRISM 4.0: Verification of Probabilistic Real-time Systems. In G. Gopalakrishnan & S. Qadeer, editors: Proc. 23rd International Conference on Computer Aided Verification (CAV’11), LNCS 6806, Springer, pp. 585–591, doi:10.1007/978-3-642-22110-1_47. [12] M. Kwiatkowska, G. Norman, D. Parker & G. Santos (2020): PRISM-games 3.0: Stochastic Game Verification with Concurrency, Equilibria and Time. In: Proc. 32nd International Conference on Computer Aided Verification (CAV’20), LNCS 12225, Springer, pp. 475–487, doi:10.1007/978-3-030-53291-8_25. [13] Sangkeun Lee, Minsuk Kahng & Sang goo Lee (2015): Constructing compact and effective graphs for recommender systems via node and edge aggregations. Expert Systems with Applications 42(7), pp. 3396–3409, doi:10.1016/j.eswa.2014.11.062. [14] Xinxin Liu & Scott A. Smolka (1998): Simple Linear-Time Algorithms for Minimal Fixed Points (Extended Abstract). In Kim Guldstrand Larsen, Sven Skyum & Glynn Winskel, editors: Automata, Languages and Programming, 25th International Colloquium, ICALP’98, Aalborg, Denmark, July 13-17, 1998, Proceedings, Lecture Notes in Computer Science 1443, Springer, pp. 53–66, doi:10.1007/BFb0055040. [15] Lawrence Page, Sergey Brin, Rajeev Motwani & Terry Winograd (1998): The PageRank Citation Ranking: Bringing Order to the Web. Technical Report, Stanford Digital Library Technologies Project. Available at http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.31.1768. This paper is available on Arxiv under CC 4.0 license. Arxiv

CGAAL: Wrapping It Up and What Comes Next

Recently, Apple released the Vision Pro, and I was fortunate enough to become a proud owner. Since then, I've been deeply engaged in developing my application and exploring various apps and trends within the Vision Pro App Store. One thing that grabbed my attention is that new apps are coming out every day, but only a few fit well with the immersive virtual reality experience. I guess many developers struggle to find documentation and examples for Vision Pro features. However, utilizing the capabilities of Vision Pro can set your application apart and provide users with an enhanced experience. In this article, I'll be sharing some tips and tricks I've uncovered while crafting my application. These tips will not only help your application to stand out but also ensure its seamless integration and native feel within VisionOS. Dark Surroundings Effect I'm sure you've noticed that when viewing a video or photo, the background behind the window is darkened, in the settings it's called "auto-dimming". To get the same effect you need to use .preferredSurroundingsEffect(.systemDark) on your view and then the space around the user will darken and your window will remain bright, this will help to keep the focus on the content. Hidden Window Controls Line When viewing a video or content, you want the user to have no distractions and create the effect of a window floating in the air, for this Apple has given us the ability to hide the bottom bar of the window that is used to move or close the current window. With .persistentSystemOverlays(.hidden) you can hide this control bar on your window, it will disappear with the default animation and only appear when the user interacts with the window. Video Reflection Effect If you open the standard Apple TV application and turn on a movie, you will notice that the movie window has a reflection that changes with each frame, giving a more immersive effect. To get a glow effect around your video, you need to use VideoPlayerComponent and enable isPassthroughTintingEnabled, then the effect will be the same as in Apple TV or HBO Max. Here is what the documentation says: This is to enable passthrough tinting during video playback that shows up around the video taking the average color of the frame and tinting the passthrough with that color to emphasize the video. Window Resizing You may want to prevent the user from resizing the window, there is a way to do that: onAppear {
    guard let windowScene = UIApplication.shared.connectedScenes.first as?UIWindowScene else { return }
    windowScene.requestGeometryUpdate(.Vision(resizingRestrictions: UIWindowScene.ResizingRestrictions.none))
} You can also specify additional size settings in this method The full signature of the method looks like this: windowScene.requestGeometryUpdate(.Vision(size:, minimumSize:, maximumSize:, resizingRestrictions:)) Hands Visibility If your application uses immersive space and you don’t want the user to see their hands, or you want to replace them with virtual hands, as is done in AmazeVR, then you need to use .upperLimbVisibility(.hidden) Ornament I'm sure you've seen sidebars in VisionOS applications that look like TabBars. Apple has introduced a new View method for VisionOS that allows you to "expand" the window and add ornaments on either side of it. .ornament(
    visibility: .visible,
    attachmentAnchor: .scene(.bottom),
    contentAlignment: .center
) {
    HStack {
        Button("Play", systemImage: "play.fill") {
        }
        Button("Stop", systemImage: "stop.fill") {
        }
        
    }
    .labelStyle(.iconOnly)
    .padding(.all)
    .glassBackgroundEffect()
} Сore location An interesting fact that I was able to verify experimentally is that CMMotionManager's methods only work in immersive space and not in the normal window view. Conclusion VisionOS provides many tools to create immersive applications that bring users into the virtual world and make them feel part of it. While more and more applications are being released for Vision Pro, only a few utilize its full range of features. That's where your chance to distinguish comes in — use them and take advantage. Unfortunately, developers struggle to find easily accessible documentation and examples. That's why I'm writing this article. I hope my tips will help you make your application better. Recently, Apple released the Vision Pro, and I was fortunate enough to become a proud owner. Since then, I've been deeply engaged in developing my application and exploring various apps and trends within the Vision Pro App Store. Apple One thing that grabbed my attention is that new apps are coming out every day, but only a few fit well with the immersive virtual reality experience. I guess many developers struggle to find documentation and examples for Vision Pro features. However, utilizing the capabilities of Vision Pro can set your application apart and provide users with an enhanced experience. In this article, I'll be sharing some tips and tricks I've uncovered while crafting my application. These tips will not only help your application to stand out but also ensure its seamless integration and native feel within VisionOS. Dark Surroundings Effect I'm sure you've noticed that when viewing a video or photo, the background behind the window is darkened, in the settings it's called "auto-dimming". To get the same effect you need to use .preferredSurroundingsEffect(.systemDark) on your view and then the space around the user will darken and your window will remain bright, this will help to keep the focus on the content. .preferredSurroundingsEffect(.systemDark) Hidden Window Controls Line When viewing a video or content, you want the user to have no distractions and create the effect of a window floating in the air, for this Apple has given us the ability to hide the bottom bar of the window that is used to move or close the current window. With .persistentSystemOverlays(.hidden) you can hide this control bar on your window, it will disappear with the default animation and only appear when the user interacts with the window. .persistentSystemOverlays(.hidden) Video Reflection Effect If you open the standard Apple TV application and turn on a movie, you will notice that the movie window has a reflection that changes with each frame, giving a more immersive effect. To get a glow effect around your video, you need to use VideoPlayerComponent and enable isPassthroughTintingEnabled , then the effect will be the same as in Apple TV or HBO Max. Here is what the documentation says: VideoPlayerComponent isPassthroughTintingEnabled This is to enable passthrough tinting during video playback that shows up around the video taking the average color of the frame and tinting the passthrough with that color to emphasize the video. This is to enable passthrough tinting during video playback that shows up around the video taking the average color of the frame and tinting the passthrough with that color to emphasize the video. Window Resizing You may want to prevent the user from resizing the window, there is a way to do that: onAppear {
    guard let windowScene = UIApplication.shared.connectedScenes.first as?UIWindowScene else { return }
    windowScene.requestGeometryUpdate(.Vision(resizingRestrictions: UIWindowScene.ResizingRestrictions.none))
} onAppear {
    guard let windowScene = UIApplication.shared.connectedScenes.first as?UIWindowScene else { return }
    windowScene.requestGeometryUpdate(.Vision(resizingRestrictions: UIWindowScene.ResizingRestrictions.none))
} You can also specify additional size settings in this method The full signature of the method looks like this: windowScene.requestGeometryUpdate(.Vision(size:, minimumSize:, maximumSize:, resizingRestrictions:)) windowScene.requestGeometryUpdate(.Vision(size:, minimumSize:, maximumSize:, resizingRestrictions:)) Hands Visibility If your application uses immersive space and you don’t want the user to see their hands, or you want to replace them with virtual hands, as is done in AmazeVR, then you need to use .upperLimbVisibility(.hidden) .upperLimbVisibility(.hidden) Ornament I'm sure you've seen sidebars in VisionOS applications that look like TabBars . Apple has introduced a new View method for VisionOS that allows you to "expand" the window and add ornaments on either side of it. TabBars View .ornament(
    visibility: .visible,
    attachmentAnchor: .scene(.bottom),
    contentAlignment: .center
) {
    HStack {
        Button("Play", systemImage: "play.fill") {
        }
        Button("Stop", systemImage: "stop.fill") {
        }
        
    }
    .labelStyle(.iconOnly)
    .padding(.all)
    .glassBackgroundEffect()
} .ornament(
    visibility: .visible,
    attachmentAnchor: .scene(.bottom),
    contentAlignment: .center
) {
    HStack {
        Button("Play", systemImage: "play.fill") {
        }
        Button("Stop", systemImage: "stop.fill") {
        }
        
    }
    .labelStyle(.iconOnly)
    .padding(.all)
    .glassBackgroundEffect()
} Сore location An interesting fact that I was able to verify experimentally is that CMMotionManager's methods only work in immersive space and not in the normal window view. Conclusion VisionOS provides many tools to create immersive applications that bring users into the virtual world and make them feel part of it. While more and more applications are being released for Vision Pro, only a few utilize its full range of features. That's where your chance to distinguish comes in — use them and take advantage. Unfortunately, developers struggle to find easily accessible documentation and examples. That's why I'm writing this article. I hope my tips will help you make your application better.

VisionOS Development: Tips and Tricks for Building Apple Vision Pro Apps

VisionOS ডেভেলপমেন্ট: অ্যাপল ভিশন প্রো অ্যাপস তৈরির জন্য টিপস এবং ট্রিকস

VisionOS-Entwicklung: Tipps und Tricks zum Erstellen von Apple Vision Pro-Apps

Desarrollo de VisionOS: consejos y trucos para crear aplicaciones Apple Vision Pro

Développement VisionOS : trucs et astuces pour créer des applications Apple Vision Pro

विज़नओएस डेवलपमेंट: ऐप्पल विज़न प्रो ऐप्स बनाने के लिए टिप्स और ट्रिक्स

VisionOS 開発: Apple Vision Pro アプリを構築するためのヒントとコツ

VisionOS 개발: Apple Vision Pro 앱 구축을 위한 팁과 요령

Desenvolvimento VisionOS: dicas e truques para criar aplicativos Apple Vision Pro

Разработка VisionOS: советы и рекомендации по созданию приложений Apple Vision Pro

VisionOS Development: Apple Vision Pro Uygulamaları Geliştirmeye İlişkin İpuçları ve Püf Noktaları

Phát triển VisionOS: Mẹo và thủ thuật để xây dựng ứng dụng Apple Vision Pro

VisionOS 开发：构建 Apple Vision Pro 应用程序的技巧和窍门

108 Stories To Learn About Website Design

Salespersons and copywriters know that the key to conversions is emotions. People make an and then rationally justify their decision. emotionally-based decision at first It is almost never the other way around. So, if you want to drive higher conversions like more email signups, more social media followers, or more sales, creating an emotional impact is key. And images are one of the most powerful ways to achieve this. When you use the right imagery in the right way, you can improve conversion rates and grow your faster. business In this post, I’ll cover some of the top ways you can leverage visuals to convert. Let’s go. Add Human Faces Think of the last time you downloaded a game or clicked on an ad because they included a person in the thumbnail. You’ve likely done it more times than you care to admit. Adding people’s faces to your home page, social media post, or some other area is certain to drive up engagement as well as conversions. Here’s what you should know about what makes faces and people so appealing to our psychology. (The following points are referenced from a post by .) Highbrow Smiles Eye Contact POV In general, images of people smiling have higher conversion rates than pictures with neutral expressions. Likewise, photos where the subject looks directly at the viewer will connect more. Finally, POV or Point of View has to do with the angle at which the viewer sees the image, i.e., an image of a person looking upwards at the viewer will create different impressions than one of an image where a person is looking away or downwards at the viewer. What you should know is that the type of expression, face, and image you choose should depend on your goal and audience. Do you want to convey professionalism? Then, a sterner expression and folded arms might be suitable. But if you want to invite people to visit your site, a smile would work better. As we’ll point out later, you need to test which images work best to drive the best results. Leverage Color There are many theories on the impact of color and while it is clear that color does make an impact on buying psychology - there’s no consistent information about what works in every scenario. Much depends on the purpose for which you use a color and where you apply it. In branding (which is related to conversions but also different), there are clear links between color and brand image. For example, browns and greens convey calmness and are often associated with greenery, energy, sustainability, and related concepts. Black is associated with professionalism and seriousness. in terms of driving leads. Red is said to have the best performance However, this doesn’t mean that if you use the color green in your content, it won’t convert. More than relying on a specific hue to get people to buy, you need to look at context and placement. For example, as long as your call to action button stands out and has a complementary color on a website, it will draw the eye and entice people to click on buy, sign up, or some other conversion metric. judge a business based on its web design - so you want to ensure that you’re leveraging how your site looks and feels to keep a steady stream of customers. 75% of people Here are some factors to consider when using color to ensure higher conversion rates: Contrast: Make sure that areas where you want the most attention have contrasting colors. Consistency: While colors are powerful, using more than 3-5 in any asset is a surefire way to lose customers. Stick a fixed number of specific colors and apply them consistently on all marketing assets. Cultural associations: Be mindful of how different cultures perceive colors. White may imply purity in some places but mourning in others. Do your research before you use a color in any geographical location. Complementarity: Never pick out colors randomly. Make sure that your palette of colors complements each other. Fortunately, there are free online tools where you can add colors you like, and the tool will automatically generate suitable colors that complement them. With these principles in mind, you’ll be better able to apply colors well in your assets to boost conversions. Think of Typography We’ve all played with changing fonts on documents as kids. We’ve used elaborate, unreadable, cursive fonts for stories. Or we played around with Comic Sans to convey fun and play. We have an intuitive understanding of the role that typography plays in conveying emotions and messages. Typography is the art and science of arranging letters to make them appealing and impactful. You should look at words and letters as visual ornaments and not just for the semantic meaning they convey. There are many ways typography can support conversions: Your choice of font will support your brand and the values consumers hold - leading to a higher likelihood of conversions Good typography creates a better user experience since it removes dissonance and ensures customers navigate an app or website easily. The choice of typography can attract a user’s attention to specific words and areas, which in turn can guide people to join an email list, buy, or take some other action. These are a few ways that typography can support higher conversions. They are visual mediums and must be leveraged to the fullest to create an impact on your audience. Use Icons and Symbols If you want to understand the power of icons and symbols, think of the emoji. It’s a standard part of modern communication where we rely heavily on text, and without emojis, we’d experience significant miscommunication and ruptured relationships. Today, icons and symbols play a big role in website and app design and they’re a powerful visual asset that can drive conversions. For example, research institute found that a ‘made-up’ symbol like a padlock icon or security badge created a greater sense of security. Baymard So, if you want to improve your payment checkout conversions, consider adding the little padlock symbol to your form in the right place. (Another interesting finding from Baymard is making the checkout process ‘robust’ by adding an outline or a line to contain the checkout form. This simple visual tactic contains the payment form and implies greater security during checkout.) In this way, make sure you use a carefully designed set of icons and symbols to make navigating your site easier and to convey ease and security on your products. Whitespace A user’s visual journey is not just influenced by the number of images on your site or app but also by the whitespace or the empty space around elements on your platform. Whitespace allows your content and features to breathe and keep users from getting overwhelmed. And when used correctly, it can draw attention to important parts of your site. So, don’t neglect to use whitespace as wisely as you do the other elements mentioned here. Carry out A/B Testing to Verify Your Design Choices No matter how experienced a UX/UI designer is, you must always test your design choices through user testing. This means presenting important visual content to your target audience base and asking for feedback. A good methodology to try is split testing or A/B testing. Give users a choice between two designs, A and B. And the one that wins the majority vote should be your design choice or improved and tested further. Only through testing can you figure out if your visual assets are impactful and create the right impression on your audience. Over to You There you have it: a breakdown of how to make your visual elements have a greater impact. Try to implement these aspects into your design, product development, and more. You’re certain to see a rise in conversions, which will lead to overall business success.

Visual Mastery: How to Create Impactful Marketing That Drives Engagement

Scientific American, Vol. XXXVII.—No. 2. [New Series.], July 14, 1877 by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . CURIOUS CARNIVOROUS PLANTS. here CURIOUS CARNIVOROUS PLANTS. The is one of the most curious of that wonderful series of carnivorous plants which at the present time are engaging the closest scrutiny of naturalists. It is a true trap in one sense—inasmuch as it captures the victim which ventures near it; but it relies on little or no mechanical means for securing its prey, but stupefies the living insect by its odor. The flower is horn-shaped, about 11 inches in length, with an opening some 5 inches in diameter. The color within is a dull dark violet, while the interior of the spathe is lined with black, hooked bristles, the whole appearance of the flower being thoroughly repulsive. The illustrations herewith presented, Figs. 1 and 2, represent it at one third its natural size, Fig. 2 showing a section of the flower. It is not certain what attracts the insects, which are usually of the species known as the meat fly and the common house fly. They do not seem to seek for the small quantity of nectar concealed, and yet they cluster about the fatal opening, as if drawn by some overpowering fascination. Overcome by lethargy, they fall inert upon the flower, are lightly held by the bristles, and finally die asphyxiated by the carbonic acid which the plant disengages in large quantities during its inflorescence. Strange as is the action of the , the method whereby the takes its prey is even more wonderful. To illustrate on a magnified scale, let the reader imagine a surface thickly covered with strong iron posts, on the sides of which are numerous keen barbs pointing downward. Then between these posts, suppose that jars overflowing with honey are placed. An elephant, let it be imagined, attracted by the profusion of sweetness, inserts his trunk between the posts and finds easy access to the honey. But while he can force his proboscis downward past the barbs turned in that direction, when he attempts to withdraw it he finds the keen points catch in the flesh, and render it impossible to do so. A terrible struggle follows, the unfortunate animal twisting and writhing in every direction, until finally by an Herculean effort the head is torn from the body, and the latter becomes digested by some potent gastric juice, exuding from the colossal organism of which the trap forms but a portion. Of course this is vastly exaggerated, and it would puzzle an elephant to pull his own head off; but if for the post studded trap, we substitute the surface of a flower, and if we replace the elephant by a fly, we shall have conceived an accurate picture of what takes place in the peculiar receptacle with which Nature has provided the . This is very beautifully shown in Fig. 3; and at A, in same figure, is represented the barbed bristles grasping the highly magnified proboscis of the fly. Between the barbed bristles are mushroom-shaped projections, from the summits of which a viscous nectar exudes. This is the honey bait which induces the insect to insert his trunk between the fatal barbs. There is still another plant, , which captures butterflies by grasping the proboscis. The construction of the flower is quite complicated, so that the insects are compelled to insert their trunks through a narrow and winding passage in order to reach the nectar. The organ then necessarily comes in contact with an adhesive substance, which prevents its removal. arum Dracunculus arum mentzelia mentzelia ornata physianthus albens The , Fig. 4, is another plant trap, which catches no flies nor possesses any such wonderfully adapted devices as the plants already described. It simply has its branches covered with double barbed bristles of great strength which attach themselves to anything brought in contact with them. The bristles are strong enough to hold lizards, as represented by our engraving, the points inserting themselves in the interstices of the scaly covering of the reptile. Of course the lizard thus held starves to death, and small birds often follow a like fate. We are indebted to for the illustrations. Gronovia scandens La Nature About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Various (2012). Scientific American, Vol. XXXVII. —No. 2. [New Series.], July 14, 1877. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/38481/pg38481-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at . www.gutenberg.org https://www.gutenberg.org/policy/license.html

CURIOUS CARNIVOROUS PLANTS

Scientific American, Volume XLIII., No. 25, December 18, 1880, by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . THE HERCULES BEETLE. here THE HERCULES BEETLE. In the handsome engraving herewith are shown the male and female of the Hercules beetle ( ) of Brazil. The family of the comprises some of the largest and most beautiful of the beetle race, and all of them are remarkable for enormous developments of the thorax and head. They are all large bodied and stout limbed, and by their great strength abundantly justify their generic name, , which is from the Greek and signifies powerful. The larvæ of these beetles inhabit and feed upon decaying trees and other rotting vegetable matter, and correspond in size with the mature insects. Most of them inhabit tropical regions, where they perform a valuable service in hastening the destruction of dead or fallen timber. Dynastes hercules Dynastidæ Dynastes An admirable example of this family of beetles is the one here represented. In the male of the Hercules beetle the upper part of the thorax is prolonged into a single, downward curving horn fully three inches long, the entire length of the insect being about six inches. The head is prolonged into a similar horn, which curves upward, giving the head and thorax the appearance of two enormous jaws, resembling the claw of a lobster. The real jaws of the insect are underneath the lower horn, which projects from the forepart of the head. The under surface of the thorax-horn carries a ridge of stiff, short, golden-yellow hairs, and the under surface and edges of the abdomen are similarly ornamented. The head, thorax, and legs are shining black; the elytra, or wing-covers, are olive-green, dotted with black spots, and are much wrinkled. The wings are large and powerful. The female Hercules is quite unlike the male. It is much smaller, being not more than three and a half inches long, is without horns, and is covered with a brown hairy felt. These beetles are nocturnal in habit, and are rarely seen in the daytime, except in dark hiding places in the recesses of Brazilian forests. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Various (2007). Scientific American, Volume XLIII., No. 25, December 18, 1880. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/21081/pg21081-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at . www.gutenberg.org https://www.gutenberg.org/policy/license.html

THE HERCULES BEETLE

Emphatic words must stand in emphatic positions

The account of the meeting of men of science at Berlin, in the autumn of 1828

On the Effect of Taxes and of Legal Restrictions upon Manufactures

THOUGHTS ON SCIENCE

On Combinations of Masters against the public

THOUGHTS ON LIFE

UNLOOKED-FOR ARRIVALS.

Steam, Its Generation and Use by Babcock & Wilcox Company, is part of the HackerNoon Books Series. You can jump to any chapter in this book . THE BABCOCK & WILCOX BOILER here THE BABCOCK & WILCOX BOILER The following brief description of the Babcock & Wilcox boiler will clearly indicate the manner in which it fulfills the requirements of the perfect steam boiler already enumerated. The Babcock & Wilcox boiler is built in two general classes, the longitudinal drum type and the cross drum type. Either of these designs may be constructed with vertical or inclined headers, and the headers in turn may be of wrought steel or cast iron dependent upon the working pressure for which the boiler is constructed. The headers may be of different lengths, that is, may connect different numbers of tubes, and it is by a change in the number of tubes in height per section and the number of sections in width that the size of the boiler is varied. The longitudinal drum boiler is the generally accepted standard of Babcock & Wilcox construction. The cross drum boiler, though originally designed to meet certain conditions of headroom, has become popular for numerous classes of work where low headroom is not a requirement which must be met. LONGITUDINAL DRUM CONSTRUCTION—The heating surface of this type of boiler is made up of a drum or drums, depending upon the width of the boiler extending longitudinally over the other pressure parts. To the drum or drums there are connected through cross boxes at either end the sections, which are made up of headers and tubes. At the lower end of the sections there is a mud drum extending entirely across the setting and connected to all sections. The connections between all parts are by short lengths of tubes expanded into bored seats. The drums are of three sheets, of such thickness as to give the required factor of safety under the maximum pressure for which the boiler is constructed. The circular seams are ordinarily single lap riveted though these may be double lap riveted to meet certain requirements of pressure or of specifications. The longitudinal seams are properly proportioned butt and strap or lap riveted joints dependent upon the pressure for which the boilers are built. Where butt strap joints are used the straps are bent to the proper radius in an hydraulic press. The courses are built independently to template and are assembled by an hydraulic forcing press. All riveted holes are punched one-quarter inch smaller than the size of rivets as driven and are reamed to full size after the plates are assembled. All rivets are driven by hydraulic pressure and held until black. The drumheads are hydraulic forged at a single heat, the manhole opening and stiffening ring being forged in position. Flat raised seats for water column and feed connections are formed in the forging. All heads are provided with manholes, the edges of which are turned true. The manhole plates are of forged steel and turned to fit manhole opening. These plates are held in position by forged-steel guards and bolts. The drum nozzles are of forged steel, faced, and fitted with taper thread stud bolts. Cross boxes by means of which the sections are attached to the drums, are of forged steel, made from a single sheet. Where two or more drums are used in one boiler they are connected by a cross pipe having a flanged outlet for the steam connection. The sections are built of 4-inch hot finished seamless open-hearth steel tubes of No. 10 B. W. G. where the boilers are built for working pressures up to 210 pounds. Where the working pressure is to be above this and below 260 pounds, No. 9 B. W. G. tubes are supplied. The tubes are expanded into headers of serpentine or sinuous form, which dispose the tubes in a staggered position when assembled as a complete boiler. These headers are of wrought steel or of cast iron, the latter being ordinarily supplied where the working pressure is not to exceed 160 pounds. The headers may be either vertical or inclined as shown in the various illustrations of assembled boilers. Opposite each tube end in the headers there is placed a handhole of sufficient size to permit the cleaning, removal or renewal of a tube. These openings in the wrought steel vertical headers are elliptical in shape, machine faced, and milled to a true plane back from the edge a sufficient distance to make a seat. The openings are closed by inside fitting forged plates, shouldered to center in the opening, their flanged seats milled to a true plane. These plates are held in position by studs and forged-steel binders and nuts. The joints between plates and headers are made with a thin gasket. In the wrought-steel inclined headers the handhole openings are either circular or elliptical, the former being ordinarily supplied. The circular openings have a raised seat milled to a true plane. The openings are closed on the outside by forged-steel caps, milled and ground true, held in position by forged-steel safety clamps and secured by ball-headed bolts to assure correct alignment. With this style of fitting, joints are made tight, metal to metal, without packing of any kind. Where elliptical handholes are furnished they are faced inside, closed by inside fitting forged-steel plates, held to their seats by studs and secured by forged-steel binders and nuts. The joints between plates and header are made with a thin gasket. The vertical cast-iron headers have elliptical handholes with raised seats milled to a true plane. These are closed on the outside by cast-iron caps milled true, held in position by forged-steel safety clamps, which close the openings from the inside and which are secured by ball-headed bolts to assure proper alignment. All joints are made tight, metal to metal, without packing of any kind. The mud drum to which the sections are attached at the lower end of the rear headers, is a forged-steel box 7¼ inches square, and of such length as to be connected to all headers by means of wrought nipples expanded into counterbored seats. The mud drum is furnished with handholes for cleaning, these being closed from the inside by forged-steel plates with studs, and secured on a faced seat in the mud drum by forged-steel binders and nuts. The joints between the plates and the drum are made with thin gaskets. The mud drum is tapped for blow-off connection. All connections between drums and sections and between sections and mud drum are of hot finished seamless open-hearth steel tubes of No. 9 B. W. G. Boilers of the longitudinal drum type are suspended front and rear from wrought-steel supporting frames entirely independent of the brickwork. This allows for expansion and contraction of the pressure parts without straining either the boiler or the brickwork, and also allows of brickwork repair or renewal without in any way disturbing the boiler or its connections. CROSS DRUM CONSTRUCTION—The cross drum type of boilers differs from the longitudinal only in drum construction and method of support. The drum in this type is placed transversely across the rear of the boiler and is connected to the sections by means of circulating tubes expanded into bored seats. The drums for all pressures are of two sheets of sufficient thickness to give the required factor of safety. The longitudinal seams are double riveted butt strapped, the straps being bent to the proper radius in an hydraulic press. The circulating tubes are expanded into the drums at the seams, the butt straps serving as tube seats. The drumheads, drum fittings and features of riveting are the same in the cross drum as in the longitudinal types. The sections and mud drum are also the same for the two types. Cross drum boilers are supported at the rear on the mud drum which rests on cast-iron foundation plates. They are suspended at the front from a wrought-iron supporting frame, each section being suspended independently from the cross members by hook suspension bolts. This method of support is such as to allow for expansion and contraction without straining either the boiler or the brickwork and permits of repair or renewal of the latter without in any way disturbing the boiler or its connections. The following features of design and of attachments supplied are the same for all types. FRONTS—Ornamental fronts are fitted to the front supporting frame. These have large doors for access to the front headers and panels above the fire fronts. The fire fronts where furnished have independent frames for fire doors which are bolted on, and ashpit doors fitted with blast catches. The lugs on door frames and on doors are cast solid. The faces of doors and of frames are planed and the lugs milled. The doors and frames are placed in their final relative position, clamped, and the holes for hinge pins drilled while thus held. A perfect alignment of door and frame is thus assured and the method is representative of the care taken in small details of manufacture. The front as a whole is so arranged that any stoker may be applied with but slight modification wherever boilers are set with sufficient furnace height. In the vertical header boilers large wrought-iron doors, which give access to the rear headers, are attached to the rear supporting frame. FITTINGS—Each boiler is provided with the following fittings as part of the standard equipment: Blow-off connections and valves attached to the mud drum. Safety valves placed on nozzles on the steam drums. A water column connected to the front of the drum. A steam gauge attached to the boiler front. Feed water connection and valves. A flanged stop and check valve of heavy pattern is attached directly to each drumhead, closing automatically in case of a rupture in the feed line. All valves and fittings are substantially built and are of designs which by their successful service for many years have become standard with The Babcock & Wilcox Co. The fixtures that are supplied with the boilers consist of: Dead plates and supports, the plates arranged for a fire brick lining. A full set of grate bars and bearers, the latter fitted with expansion sockets for side walls. Flame bridge plates with necessary fastenings, and special fire brick for lining same. Bridge wall girder for hanging bridge wall with expansion sockets for side walls. A full set of access and cleaning doors through which all portions of the pressure parts may be reached. A swing damper and frame with damper operating rig. There are also supplied with each boiler a wrench for handhole nuts, a water-driven turbine tube cleaner, a set of fire tools and a metal steam hose and cleaning pipe equipped with a special nozzle for blowing dust and soot from the tubes. Aside from the details of design and construction as covered in the foregoing description, a study of the illustrations will make clear the features of the boiler as a whole which have led to its success. The method of supporting the boiler has been described. This allows it to be hung at any height that may be necessary to properly handle the fuel to be burned or to accommodate the stoker to be installed. The height of the nest of tubes which forms the roof of the furnace is thus the controlling feature in determining the furnace height, or the distance from the front headers to the floor line. The sides and front of the furnace are formed by the side and front boiler walls. The rear wall of the furnace consists of a bridge wall built from the bottom of the ashpit to the lower row of tubes. The location of this wall may be adjusted within limits to give the depth of furnace demanded by the fuel used. Ordinarily the bridge wall is the determining feature in the locating of the front baffle. Where a great depth of furnace is necessary, in which case, if the front baffle were placed at the bridge wall the front pass of the boiler would be relatively too long, a patented construction is used which maintains the baffle in what may be considered its normal position, and a connection made between the baffle and the bridge wall by means of a tile roof. Such furnace construction is known as a “Webster” furnace. A consideration of this furnace will clearly indicate its adaptability, by reason of its flexibility, for any fuel and any design of stoker. The boiler lends itself readily to installation with an extension or Dutch oven furnace if this be demanded by the fuel to be used, and in general it may be stated that a satisfactory furnace arrangement may be made in connection with a Babcock & Wilcox boiler for burning any fuel, solid, liquid or gaseous. The gases of combustion evolved in the furnace above described are led over the heating surfaces by two baffles. These are formed of cast-iron baffle plates lined with special fire brick and held in position by tube clamps. The front baffle leads the gases through the forward portion of the tubes to a chamber beneath the drum or drums. It is in this chamber that a superheater is installed where such an apparatus is desired. The gases make a turn over the front baffle, are led downward through the central portion of the tubes, called the second pass, by means of a hanging bridge wall of brick and the second baffle, around which they make a second turn upward, pass through the rear portion of the tubes and are led to the stack or flue through a damper box in the rear wall, or around the drums to a damper box placed overhead. The space beneath the tubes between the bridge wall and the rear boiler wall forms a pocket into which much of the soot from the gases in their downward passage through the second pass will be deposited and from which it may be readily cleaned through doors furnished for the purpose. The gas passages are ample and are so proportioned that the resistance offered to the gases is only such as will assure the proper abstraction of heat from the gases without causing undue friction, requiring excessive draft. The method in which the feed water is introduced through the front drumhead of the boiler is clearly seen by reference to the illustration. From this point of introduction the water passes to the rear of the drum, downward through the rear circulating tubes to the sections, upward through the tubes of the sections to the front headers and through these headers and front circulating tubes again to the drum where such water as has not been formed into steam retraces its course. The steam formed in the passage through the tubes is liberated as the water reaches the front of the drum. The steam so formed is stored in the steam space above the water line, from which it is drawn through a so-called “dry pipe.” The dry pipe in the Babcock & Wilcox boiler is misnamed, as in reality it fulfills none of the functions ordinarily attributed to such a device. This function is usually to restrict the flow of steam from a boiler with a view to avoid priming. In the Babcock & Wilcox boiler its function is simply that of a collecting pipe, and as the aggregate area of the holes in it is greatly in excess of the area of the steam outlet from the drum, it is plain that there can be no restriction through this collecting pipe. It extends nearly the length of the drum, and draws steam evenly from the whole length of the steam space. Patented Side Dusting Doors The large tube doors through which access is had to the front headers and the doors giving such access to the rear headers in boilers of the vertical header type have already been described and are shown clearly by the illustrations on pages and . In boilers of the inclined header type, access to the rear headers is secured through the chamber formed by the headers and the rear boiler wall. Large doors in the sides of the setting give full access to all parts for inspection and for removal of accumulations of soot. Small dusting doors are supplied for the side walls through which all of the heating surfaces may be cleaned by means of a steam dusting lance. These side dusting doors are a patented feature and the shutters are self closing. In wide boilers additional cleaning doors are supplied at the top of the setting to insure ease in reaching all portions of the heating surface. 56 74 The drums are accessible for inspection through the manhole openings. The removal of the handhole plates makes possible the inspection of each tube for its full length and gives the assurance that no defect can exist that cannot be actually seen. This is particularly advantageous when inspecting for the presence of scale. The materials entering into the construction of the Babcock & Wilcox boiler are the best obtainable for the special purpose for which they are used and are subjected to rigid inspection and tests. The boilers are manufactured by means of the most modern shop equipment and appliances in the hands of an old and well-tried organization of skilled mechanics under the supervision of experienced engineers. About HackerNoon Book Series: We bring you the most important technical, scientific, and insightful public domain books. This book is part of the public domain. Babcock & Wilcox Company (2007). Steam, Its Generation and Use. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/22657/pg22657-images.html This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at , located at . www.gutenberg.org https://www.gutenberg.org/policy/license.html

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