TechGraph

techgraph

HackerNoon editorial team has launched to celebrate their achievements and share their struggles. We need more women in technology, and by sharing stories, we can encourage many girls to follow their dreams. ! this interview series with women in tech Share your story today Tell us about yourself! Absolutely! Well, to start, I'm passionate about clean/green tech and always seeking opportunities to support companies in adopting this approach, whether through investing, advising, or facilitating connections with relevant parties. I'm driven by the prospect of offering affordable products that rely entirely on renewable energy for charging, eliminating the need for wired connections. I'm particularly proud of the recognition my work has received within the telecommunications industry, such as the from CorpLiveWire for our product and overall affiliations. Overall, I'm excited about the chance to apply my skills and passion not only at my company, but also to contribute to other startups/SMEs, working towards achieving a carbon-neutral world by 2035. Specialist Telecommunications Agency Award 2023 Roam Telecoms Why did you choose this field in the first place? I chose to pursue a career in green and clean tech because I grew tired of constantly dealing with my phone's battery issues. I found it frustrating, especially when trying to stay active outdoors while relying on my phone for various tasks. This frustration, coupled with my New Year's resolution to adopt a healthier lifestyle, sparked the idea of creating a portable device that could be charged using solar energy. It was a light bulb moment for me, realizing the potential of utilizing the sun's energy to power everyday devices. This inspiration led me to develop the Roam Solar Phone, a product designed to provide a sustainable and reliable solution to the problem of battery life while on the go, and launch it during my final year of business school. What tech are you most excited/passionate about right now and why? Currently, I'm most excited about green and clean tech, particularly the advancements in solar-powered devices. My passion for this technology stems from personal frustration with traditional battery-powered devices and a desire to find sustainable solutions. The potential of harnessing solar energy to power everyday devices, like the Roam Solar Phone and the rest of our IP portfolio, and being able to push the R&D of future products to develop and being able to one day offer it to the masses at an affordable rate, is incredibly exciting to me. I believe that embracing green and clean tech not only addresses environmental concerns but also offers practical and innovative solutions to everyday challenges by being able to create a universal product everyone can be able to buy without breaking the bank and knowing the technology will last years. What tech are you most worried about right now and why? One area of technology that concerns me greatly is the issue of e-waste. The rapid advancement of technology has led to a constant stream of new gadgets and devices being introduced into the market, resulting in a significant increase in electronic waste. This e-waste poses serious environmental and health risks, as many electronic devices contain toxic materials that can leach into the soil and water if not disposed of properly. Additionally, the improper disposal of e-waste contributes to pollution and greenhouse gas emissions, further exacerbating the climate crisis. We must address this issue by promoting responsible recycling and disposal practices, as well as encouraging manufacturers to design products with longevity and recyclability in mind. By taking action to mitigate the impact of e-waste, we can work towards building a more sustainable and environmentally friendly future. What are your hobbies and interests outside of tech? Outside of my work in tech, I prioritize my health and well-being by engaging in various activities that allow me to unwind and recharge. I enjoy staying active through activities like going for a run or attempting to do yoga, which not only keeps me physically fit but also helps me maintain a balanced mindset. Additionally, I'm passionate about continuously improving my soft skills and interpersonal abilities, so I often seek out opportunities for personal development and self-improvement through networking events, courses, or even by reading. Spending quality time with my family and friends is also a top priority for me, as I value the connections and new memories we create together. Whether it's exploring new places, trying out new restaurants, or simply enjoying each other's company at home, these moments are incredibly meaningful to me. Let's talk about breaking the glass ceiling. What were the biggest challenges you faced as a woman in tech, and how did you deal with them? As a woman in the tech industry, I've faced the significant challenge of feeling overlooked or underestimated due to my gender and age in certain professional settings. However, I've learned to perceive these moments not as obstacles but as opportunities for personal growth and self-reflection. When I find myself in an environment where my contributions are not valued or respected, I realize that it may not be the right fit for me. Thus, I actively seek out spaces where my voice is heard and my perspective is valued. Fortunately, I've been privileged to surround myself with a supportive network of individuals who share a common vision and embrace the power of diversity and inclusion within the industry. By aligning myself with like-minded peers and mentors who champion these values, I've been able to overcome these challenges and continue to thrive in the tech sector, contributing my unique perspective and expertise. Any questionable misogynistic story/situation you faced/handled, and you want to share with the HackerNoon Fam? While raising a Series A round for an energy start-up in late 2022, I encountered a situation where a capital partner company in London consistently undermined me, suggesting it would be better to hear from a man. Despite leading the investment round and possessing in-depth technical knowledge of the project, I was subjected to this dismissive behavior, because the information coming from a female wouldn’t be correct as if it were coming from a male engineer. I was simply taken aback, I ended up closing the meeting and looking for other investors who’d share the same vision as myself. If any investors talk down to a founder or any team member, because of their gender, I would highly suggest you walk away from the investment, as chances are if the LP has treated you this way and thinks it’s right then they’re doing it to others. It was a stark reminder of the stigma female founders, especially women of color, often face in the startup world. highlighted that only 3% of venture-backed companies are female-led, with even fewer if you're a person of color. Despite these challenges, I persisted, connected with the right individuals, and ultimately secured funding for the venture. Harvard Business Review What was the biggest setback/failure that you faced, and how did you manage it? One significant setback occurred in 2020 during the peak of the COVID-19 pandemic and the Global Chip Shortage, impacting various hardware-based industries, including automotive. To overcome this, we implemented an in-house initiative to recycle components and collaborated with IT companies to prevent e-waste. By recycling, extracting, and testing semiconductors, we were able to reuse them in client prototypes, mitigating the impact of the shortage. Another setback during the same period involved a failed PCB board delivery, with the manufacturer incorrectly altering the joints from our original file during production. We resolved this issue by manually jumping the board, although it prompted us to explore alternatives, such as 3D printing our PCBs internally for more effective control over production quality. What's your biggest achievement that you're really proud of? My greatest achievement comes from my professional accomplishments, which include building an extensive IP portfolio at Roam Telecoms alongside my exceptional team. Additionally, as a co-founder of , my media company, I'm excited about our upcoming launch of a new subsidiary company specializing in PR. Moreover, my role in an Asset Management company has afforded me the opportunity to work closely with SMEs, offering mentorship, facilitating connections, and making investments. I find great fulfillment in sharing knowledge and fostering a ripple effect where others can similarly empower those around them. TechGraph In your opinion, why do we see this huge gender gap in the tech industry, and how can we reduce it? The underrepresentation of women in tech can be attributed to several deep-rooted cultural and systemic factors, including early gender stereotyping that steers girls away from STEM fields, lack of prominent female role models, gender biases and discrimination in hiring and workplace cultures, and funding disparities faced by female tech entrepreneurs. Addressing this significant gender gap requires a multi-faceted approach, spanning educational reforms with focused STEM outreach for girls and revamped curricula, workplace initiatives like diversity training, fair practices, and anti-harassment policies, as well as increased investment and mentorship opportunities for women in tech. Fundamentally, achieving gender parity in the industry necessitates a cultural shift in attitudes towards women, coupled with systemic changes in education, workplaces, and funding ecosystems to create an inclusive and supportive environment that taps into the entire talent pool. Who is your tech idol? Why? I don’t really have a tech idol, but I would say my mother and my older sisters, as each female member of my family possess a trait to that I admire and work towards honing. Do you have any advice for aspiring girls who want to join the field? Don’t be afraid to step outside your comfort zone and speak up, always follow your gut instinct and pave your own path. Most importantly, always remember your worst days are actually your best, you learn a lot from it.

Women in Tech: Shanaz Khan's Journey of Building Sustainable Solutions in Tech

Startups Of The Year 2023: Asia Winners

The wait is over! - it’s time to celebrate the champion startups of the world. Shout out to all of the participants in our ! You did a wonderful job showcasing your incredible startups and powering through another year. 2023 Startups of the Year is a community-driven voting platform brought to you by HackerNoon that recognizes and celebrates tech startups changing technology and the world for the better. The award started on May 8th, 2023, where the internet nominated and voted for 30k startups around the world. The voting period remained open until December 31, 2023, and now we are here with the winner announcement after a comprehensive evaluation by the HackerNoon team. Startups of the Year 2023 To see the top 3 startups in each respective city, visit and pick a city. hackernoon.com/startups You’ll get a little surprise 😉 Here are the Startups of the Year Regional Announcements: North America Europe Asia Africa South America Oceania Misc/Remote From all of us at HackerNoon, thank YOU for your excellent campaign perseverance 🥺 This year has been awesome! Startups of the Year 2023 is concluded with 623k+ total votes, up from 215k+ votes in the inaugural startup competition. We look forward to seeing you again in the next campaign (stay tuned 😉)! Without further ado, let us kick off the announcement by celebrating the cities with top votes per region for 2023 🎉 North America (11,697 votes): Winner: Bloomfilter Cleveland, Ohio (8,835 votes) - Winner: SerpApi Austin, Texas , California (5,564 votes) - Winner: Finch San Francisco (4,258 votes) - Winner: RELAYTO SoMa, California - (3339 votes) Winner: Windscribe Toronto, Canada, North America (3304 votes) - Winner: Vouched Seattle (2716 votes) - Winner: Seccuri Palo Alto, CA, North America (2671 votes) - Winner: Salsa Valley Miami, FL, North America (2,613 votes) - Winner: Majhi Group Manhattan, New York (2423 votes) - Winner: Flieber, Inc. New York City, NY, North America See the complete announcement for the . Startups of the Year, North America, here Europe (45,612 votes) - Winner: Algomo London, UK (2,344votes) - Winner: Data Lake Warsaw, Poland (1,955 votes) - Winner: Hoken Tech Bari, Italy (1716 votes) - Winner: Not8 Amsterdam, Netherlands (1657 votes) - Winner: KYVE Frankfurt Am Main, Germany (1566 votes) - Winner: BazaIT Kyiv, Ukraine (1496 votes) - Winner:  Unity Network Tallinn, Estonia (1,478 votes) - Winner: Volcaino Ghent, Belgium (1,288 votes) - Winner: Owl Me Dublin, Ireland (1198 votes) - Winner: Groover Paris, France See the complete announcement for the . Startups of the Year, Europe, here Oceania (3,350 votes) - Winner: Sharepass Melbourne (2,107 votes) - Winner: The Catfisher Project Perth, Australia (220 votes) - Winner: Gemini AI Solutions Auckland, New Zealand, Oceania (213 votes) - Winner: Nexustorage Wellington, New Zealand, Oceania (138 votes) - Winner: Coviu Sydney (124 votes) - Winner: Bopple Brisbane, Australia, Oceania (124 votes) - Winner: Regional CFO New South Wales, Australia, Oceania (106 votes) - Winner: Edit on the Spot Gold Coast, Australia, Oceania (93 votes) - Winner: Knowledge Satnav Canbera, Australia, Oceania , Australia, Oceania (48 votes) - Winner: Peptalk360 North Melbourne, Melbourne See the complete announcement for the . Startups of the Year, Oceania, here Asia (16,345 votes) - Winner: Serenity Shield Singapore (13,588 votes) - Winners: QUIXY Telangana, India (10,168 votes) - Winner: HealthySure Mumbai, India (3,865 votes) - Winner: InterviewBuddy Visakhapatnam, India (3,733 votes) - Winner: Omniflo Bengaluru, India (4589 votes) - Winner: MeNow Tel Aviv (3877 votes) - Winner: ForestVPN Dubai (2478 votes) - Winner: TechGraph Powai, Mumbai, India (1004 votes) - Winner: Reelo Ahmedabad, GJ, India (875 votes) - Winner: Debt Hunter Hong Kong, China See the complete announcement for the . Startups of the Year, Asia, here Africa (8,179 votes) - Winner: GO PLATFORM Algiers, Algeria (767 votes) - Winner: Tudu Accra, Ghana (415 votes) - Winner: Treford Lagos, Nigeria (265 votes) - Winner: Phalconwise Ogbomosho, Nigeria (157 votes) - Winner: AbuErdan Cairo (151 votes) - Winner: Eazipay Lekki (144 votes) - Winner: KaziConnect Dar es Salaam, Tanzania (101 votes) - Winner: faceATT Gauteng, South Africa (79 votes) - Winner: Dimagi Cape Town (71 votes) - Winner: Sabi Addis Ababa See the complete announcement for the . Startups of the Year, Africa, here South America (376 votes ) - Winner: UpGirl Santiago, Chile (217 votes) - Winner: Klever Sao Paulo, Brazil (191 votes) - Winner: Tributo Simple Buenos Aires, Argentina (127 votes) - Winner: Light-it Montevideo, Uruguay (87 votes) -Winner: Thousand Antioquia, Colombia (108 votes) - Winner: GetLavado Lima (101 votes) - Winner: Cogniflow Medellin (73 votes) - Winner: TPAGA Bogota (73 votes) - Winner: Reliv Quito (47 votes) - WInner: Quantex Cordoba See the complete announcement for the . Startups of the Year, South America, here Misc/Remote: Featured Startups (1500 votes) - Winner: CIC Chain Remote, Earth (1193 votes) - Winner: Reship Colony US Misc (146 Votes) - Winner: Partful UK, Misc (116 votes) - Winner: GoMining British Virgin Islands Misc (283 Votes) - Winner: tomorrowSpace Germany Misc (225 votes) - Winner: Dtravel Cayman Islands See the complete announcement for Misc/Remote startups . here Once again, HUGE CONGRATULATIONS and BIG PROPS to all of the top Startups of each region this year! The whole team at HackerNoon would like to thank you for your perseverance in the campaign, and we look forward to seeing you in the next campaign. About HackerNoon’s Startups Of The Year Startups of The Year is HackerNoon’s Flagship community-driven event celebrating startups that survived and thrived in 2023. 30,000 startups across 4200+ cities and six continents participated this year to be crowned the best startup in their city. Visit our page to learn more. FAQ Companies that blog more get 67% more leads - Jumpstart your company’s blogging journey by purchasing our . Business Blogging Package The 2023 Startups Of The Year is sponsored by: . . The winners get a free .Tech Domain, a HackerNoon NFT, and a Tech Company News Page. TECH Domains

Stand Up for the Champion Startups of the Year! 

বছরের চ্যাম্পিয়ন স্টার্টআপের জন্য দাঁড়ান!

Setzen Sie sich für die Champion-Startups des Jahres ein!

¡Defiende a las startups campeonas del año!

Défendez les startups championnes de l’année !

वर्ष के चैंपियन स्टार्टअप के लिए खड़े रहें!

今年のチャンピオンスタートアップのために立ち上がろう!

올해의 챔피언 스타트업을 위해 일어서세요!

Defenda as startups campeãs do ano!

Встаньте на защиту стартапов-чемпионов года!

Yılın Şampiyon Startup'ları için Ayağa Kalkın!

Hãy ủng hộ các công ty khởi nghiệp vô địch của năm!

为年度冠军初创企业挺身而出！

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 . The Speaking Telegraph. here The Speaking Telegraph. We have heretofore given accounts of the wonderful success of Professor Bell in transmitting the vibrations of the human voice by electrical means over a telegraph wire. He has lately made improvements in his method of transmission, by which he dispenses with the use of the battery, and substitutes the magneto-electric plan of producing the current. The Boston describes a recent experiment with the new apparatus, by which conversation and singing was successfully carried on between Boston and Malden, a distance of six miles. The telephone, in its present form, consists of a powerful compound permanent magnet, to the poles of which are attached ordinary telegraph coils of insulated wire. In front of the poles, surrounded by these coils of wire, is placed a diaphragm of iron. A mouthpiece to converge the sound upon this diaphragm substantially completes the arrangement. As is well known, the motion of steel or iron in front of the poles of a magnet creates a current of electricity in coils surrounding the poles of the magnet, and the duration of this current of electricity coincides with the duration of the motion of the steel or iron moved or vibrated in the proximity of the magnet. When the human voice causes the diaphragm to vibrate, electrical undulations are induced in the coils environing the magnets, precisely analogous to the undulations of the air produced by that voice. These coils are connected with the line wire, which may be of any length, provided the insulation be good. The undulations which are induced in these coils travel through the line wire, and, passing through the coils of an instrument of precisely similar construction at the distant station, are again resolved into air undulations by the diaphragm of this instrument. Transcript The experiments were as follows: Telephones having been connected with the private telegraphic line of the Boston Rubber Shoe Company, conversation was at once commenced. Stationed at the Boston end of the wire, Professor Bell requested Mr. Watson, who was at the Malden end, to speak in loud tones, with a view of enabling the entire company at once to distinguish the sounds. This was so successful that a smile of mingled pleasure and surprise played on the features of those present. That it, however, might not be supposed that loud speaking was essential to intelligibility, Mr. Bell explained that soft tones could be heard across the wires even more distinctly than loud utterances, even a whisper being audible. In confirmation of this statement, Mr. Watson commenced speaking in turn with each member of the company; and after the efficiency of this method had been proved to the satisfaction of all, he took up a newspaper and informed the assemblage that gold had closed the previous evening at New York at 105-5/8. As there were quite a number of business men present, the effect that this practical demonstration of the value of the telephone produced can scarcely be exaggerated. Other passages from the daily journals were then given, and by this time the desire for conversation having become general, Mr. Watson was plied with questions such as: "Is it thawing or freezing at Malden? Who will be the next President?" etc. It was remarkable that Mr. Watson was able to distinguish between the voices at the Boston end, he calling at least one gentleman by name as soon as the latter commenced speaking. This went on for some time, until a lady at the Malden end sent the company an invitation to lunch per telephone, and an appropriate response was made by the same medium. At length the Boston company were requested to remain quiet while a lady at the other end conveyed to them the sweet strains of music. The assemblage thereupon listened with rapt attention while a young lady commenced singing "The Last Rose of Summer." The effect was simply charming. The sound of the voice penetrated into the Boston end of the telephone with distinctness equal to that attainable in the more distant parts of a large concert room, and a unanimous vote of thanks was sent by the handy little instrument which had procured for the assemblage so agreeable an hour. The superb steam engine built by C.H. Brown & Co., of Fitchburg, Mass., which was illustrated and described on page 1 of our current volume, has been purchased by Messrs. Phineas Jones & Co., and is being erected in their extensive carriage wheel works at Newark, N.J. 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

The Speaking Telegraph

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 . NEW TELEGRAPH INSULATOR. here NEW TELEGRAPH INSULATOR. The insulator represented in the annexed engraving was originally designed to meet the requirements of South American telegraph service, but it is equally well adapted to lines in other places. The main idea is to avoid breakage from expansion and contraction in a climate subject to sudden changes of temperature, and to avoid the mischief occasioned by a well known South American bird, the "hornero," by building nests of mud on the brackets and insulators. With this insulator these nests cannot cause a weather contact or earth; on the contrary, the nest rather improves the insulation. The sectional view, Fig 2, shows the construction of the insulator and the manner of fastening it to the cross arm or bracket. A rubber ring is placed between the upper end of the porcelain insulator and the cross arm, and another similar ring is placed between the head of the suspending screw and the bottom of the insulator. It will be noticed that with this construction the insulator cannot be broken by the contraction of the screw or by the swelling of the cross-piece. This insulator can be used on an iron bracket and in connection with either iron or wooden posts, and is in every way more secure than the insulators in common use. The first cost of these insulators compares favorably with the cheapest in market, while it is less liable to breakage, lasts longer, and gives better results. It has been patented in this country and in Europe. Further information maybe obtained by addressing Mr. J. H. Bloomfield, Concordia, Entre Reos, Argentine Republic, South America. 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

NEW TELEGRAPH INSULATOR

Scientific American Supplement, No. 365, December 30, 1882 by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . APPARATUS FOR MEASURING ELECTRICITY AT THE UPPER SCHOOL OF TELEGRAPHY. here APPARATUS FOR MEASURING ELECTRICITY AT THE UPPER SCHOOL OF TELEGRAPHY. —On a former occasion I described an instrument to which, in 1873, I gave the name , and which is nothing else than a tuning fork whose motion is kept up electrically in such a way as to last indefinitely, provided that the elements of the pile are renewed gradually, and that from time to time the metallic contact is changed, which causes, at every oscillation, the current to pass from the pile into the magnet, which keeps up the vibration. Electro Tuning Forks and their Uses. Electro-Tuning Fork We reproduce herewith, in Fig. 1, a cut showing in projection one of the simplest forms of the apparatus. If we imagine the platinum or steel style, , of the figure to be done away with, as well as the platinized plate, I, and its communication with the negative pole of the pile, P, we shall have the ordinary instrument kept in operation electrically by the aid of the electro-magnet, E, the style, , the interrupting plate, I, and the pile. s s If we preserve the parts above mentioned, the instrument will possess the property of having vibrations of a constant amplitude if sufficient energy be kept up in the pile. In fact, when the amplitude is sufficiently great to cause the style, , to touch the plate, I, it will be seen that at such a moment the current no longer passes through the electromagnet, and the vibration is no longer maintained. The amplitude cannot exceed an extent which shall permit the style, , to touch I. s s Under such conditions, the duration of the vibrations remains exactly constant, as does also the vibratory intensity of the entire instrument. The measurement of time, then, by an instrument of this kind is, indeed, as perfect as it could well be. This complication in the arrangement of the apparatus has no importance as regards those tuning forks the number of whose vibrations exceeds a hundred per second, for in such a case these are given an amplitude of a few millimeters only; but it would be of importance with regard to instruments whose number of vibrations is very small, and to which it might be desirable to give great amplitude; for then, as I have long ago shown, the duration of the oscillation would depend a little on the amplitude, but a very little, it is true. I shall not refer now to the applications of these instruments in chronography, but will rather point out first the applications in which they are destined to produce an effective power. For this purpose it is necessary to make them pretty massive. The number of the vibrations depends upon such massiveness, and it is necessity to know the relation which exists between these two quantities in order to be able to construct an instrument under determinate conditions. I made in former years such a research with regard to tuning forks of prismatic form, that is to say, of a constant rectangular section continuing even into the bent portion where the parallel branches are united by a semicylinder, at the middle of which is the wrought iron rod as well as the branches. The of the instrument is the dimension parallel to the vibrations; its is the dimension which is perpendicular to them, and its is reckoned from the extremity of the branches up to the middle of the curved portion. thickness width length It is found that the number of vibrations is independent of the width, proportional to the thickness, and very nearly inverse ratio of the square of the length, provided the latter exceeds ten centimeters. If we represent the length by , the thickness by , and the number of vibrations by , we shall have the following formula: l e n = × ( / 2) n k e l in which is a constant quantity whose value depends upon the nature of the metal of which the tuning fork is made. k This constant varies very little from steel to malleable cast iron, and it may be taken as equal to 818270. Thus, then, we have a means of constructing a tuning fork in which two of the three quantities, , , , are given in advance. Experience proves that no errors are committed exceeding one or two per cent. n e l It is seen from this that there is a means of increasing the mass of the instrument without changing anything in the thickness, the length or, consequently, the number of vibrations, and this is by increasing the . breadth It is in this way that I have succeeded in having long massive tuning forks made of malleable iron, giving no more than 12 to 15 vibrations per second, and vibrating with perfect regularity. Fig. 2, annexed, shows one of these instruments of about 55 centimeters length, whose breadth, E, is from 5 to 6 centimeters, and which makes about fifteen double vibrations per second only. This number might be still further reduced, but at the expense of our being led to exaggerate the longitudinal dimensions of the apparatus in such a way as to make it inconvenient. The object may be attained more simply by loading the branches with slides supporting leaden weights, M, of 500 grammes each. By fixing these slides at different points on the branches, the number of vibrations can be made to vary from simple to double, and even triple. Thus, by fixing them at the extremity of the branches the number of the vibrations is reduced to 5 or 6. There will be seen in the figure the electro-magnet which keeps up the vibration. This is formed of three simple electro-magnets, whose bobbins have a resistance of no more than 10 ohms, and which are united in series. The interrupting plate, P, against which the style, , rests at each vibration, is capable of a forward movement, or one of recoil, by the aid of a screw, V, and of an eccentric movement which is produced by a small handle, , and during which its plane remains invariable. This arrangement permits the point of contact of the style and plate to be varied without changing the precision with which the contact takes place, and all the points of the plate to be slowly used in succession before replacing it. The motion is produced by means of a relatively weak pile, whose poles are connected to the terminals, A and A'. Three Callaud elements of triple surface, renewed one after the other every month at the most, are sufficient to keep up the vibrations continuously, day and night, without interruption, and that too even when the instrument is employed in producing a small mechanical power, as we shall see further on. s m We have now seen how electro-tuning forks may be constructed of large dimensions, of large mass, and giving a small number of vibrations per second. Such instruments are well fitted to perform the role of electrical interrupters, and it was in such a character that one of them figured in the Exhibition of the Upper School of Telegraphy as a type of an interrupter for testing piles. When it is desired to test a pile to ascertain the practicability of employing it in telegraphy, it is necessary to make it perform a work which shall be as nearly as possible identical with that which it will be called on to do, until it is used up, to estimate the duration of such work, to measure regularly the constants of the pile, the electro-motive power, and the internal resistance. Usually, in telegraphy, this work consists in sending over a line of a certain resistance intermittent currents, through the intermedium of suitable manipulators. It suffices then to cause the branches of the electro tuning fork to play the role of one of these manipulators. For doing this the tuning fork carries two insulating ebonite or ivory strips, B B (Fig. 3), which, at every oscillation, abut against vertical brass springs, . Each of these latter is located in front of the platinized point of a screw, , which is affixed to a small metallic tongue. The springs and tongues are insulated from each other, and are mounted on a piece which may be moved by a screw, V, so as to cause the springs of the strips, B B', to approach or recede according to the amplitude of the instrument's vibrations. Each spring and tongue is connected with terminals affixed to the base of the apparatus. One of the poles of one element, P, of the pile is connected with the tongue and corresponding screw, while the other pole is connected with the screw in front of it through the intermedium of a galvanometer, 2, which gives the intensity of the intermittent current, and of a resistance coil, 2, which performs the role of an artificial telegraph line. The apparatus being set in operation, it will be seen that the current from the pile is emitted once at every vibration. r v g b Thus there may be exhausted as many pile elements as there are springs, and that, too, simultaneously; and the contacts of the screws and springs can be regulated in such a way that the duration of the emissions shall be the same for all. At the laboratory of the School of Telegraphy one of these instruments has operated without interruption, day and night, during eighteen months. The apparatus shown in Fig. 4 is also an interrupting electro-tuning fork, but it makes a much greater number of vibrations than the preceding, and may serve for other electric tests. The operation of the tuning fork is kept up electrically by the aid of the screw, , and the corresponding plate; of the style, , and of the fine wire spiral spring, , both insulated from the fork, from the electro-magnet, N, and from the two wires, F F', which communicate with a pile. v s f The interrupting system is symmetrical with the first. It consists of the style, , of the spiral spring, , of the screw, , and of the plate that this carries at its extremity. The terminal, B, which carries the spring, , and the rod which carries the screw being insulated from each other, it is only necessary to cause to terminate therein the extremities of a circuit comprising one pile, in order to produce in the circuit a number of interruptions equal to that of the tuning fork's vibrations. Provided the lengths of the springs, and , are proper, such vibrations will not be altered. s f v f f f' Moreover, the instrument is so arranged as to produce vibrations whose during the whole time the experiments last. This is done by modifying the of the vibrations; for the greater the amplitude, the longer likewise the duration of the contact of the style, , on the corresponding plate, and the shorter the duration of the interruption. In order to modify the amplitude, the action of the electro-magnet on the branches of the apparatus is made to vary. To effect this, the electro-magnet is made movable perpendicularly by the aid of a screw, V, between two slides, so that the core, N, may be moved with respect to the median line of the branches, and even be raised above them. Its action diminishes, necessarily, while it is being raised, and the amplitude of the vibrations likewise diminishes gradually and continuously. It may thus be made, without difficulty, to vary from two to three tenths of a millimeter to three or four millimeters or more. duration can be varied at pleasure and kept constant amplitude s But it is not sufficient to cause the amplitude to vary; it is necessary to measure it and to keep it constant at the value desired. The measurement is effected by the aid of a very simple apparatus that I have before described under the name of the . This is a small square of paper carrving a design like that shown in Fig. 5, and which is seen in Fig. 4 glued to one of the masses, M, which serve to vary the number of the instrument's vibrations. This figure is in fact, an angle, one of whose sides is graduated into millimeters, for example, and the other forms the edge of a wide black band. The apex of the angle is above and the divided side is perpendicular to the direction of the vibrations. vibrating micrometer Under such conditions, when the fork is vibrating, the apex of the angle, by virtue of the persistence of impressions upon the retina, to advance along the graduation in measure as the amplitude of the vibrations increases. If an angle has been drawn such that the slope of one of its sides to the other is one-tenth, it is easy to see that for each millimeter passed over by the apex of the angle, the amplitude will increase by two-tenths of a millimeter. seems apparently This is the way, then, that the amplitude is measured. On another hand, it suffices to keep the apex of the angle of the micrometer immovable, in order to be sure of the constancy of the tuning fork's amplitude; and this is done, when necessary, by causing the screw, V, to move slightly. The instrument represented in Fig. 4 is, moreover, fixed to a support devised by Mr. A. Duboscq, so as to make it possible to give the tuning fork every position possible with respect to a vertical plane; to raise it or lower it, and to move it backward or forward so that it may be employed for chimography, and in all those experiments in which electro-tuning folks are used. E. MERCADIER. 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 Supplement, No. 365, December 30, 1882. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/18763/pg18763-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

APPARATUS FOR MEASURING ELECTRICITY AT THE UPPER SCHOOL OF TELEGRAPHY

Scientific American, Volume 40, No. 13, March 29, 1879, by Various, is part of the HackerNoon Books Series. You can jump to any chapter in this book . Origin and Progress of Ocean Telegraphy. here Origin and Progress of Ocean Telegraphy. At the celebration in this city of the twenty-fifth anniversary of the formation of the company for laying the first Atlantic cable, Monday, March 10, the projector of the enterprise, Mr. Cyrus W. Field, spoke as follows: Neighbors and Friends: Twenty-five years ago this evening, in this house, in this room, and on this table, and at this very hour, was signed the agreement to form the New York, Newfoundland and London Telegraph Company—the first company ever formed to lay an ocean cable. It was signed by five persons, four of whom—Peter Cooper, Moses Taylor, Marshall O. Roberts, and myself—are here to-night. The fifth, Mr. Chandler White, died two years after, and his place was taken by Mr. Wilson G. Hunt, who is also present. Of my associates, it is to be said to their honor—as might have been expected from men of their high position and character—that they stood by the undertaking manfully for twelve long years, through discouragements such as nobody knows but themselves. Those who applaud our success know little through what struggles it was obtained. One disappointment followed another, till "hope deferred made the heart sick." We had little help from outside, for few had any faith in our enterprise. But not a man deserted the ship: all stood by it to the end. My brother Dudley is also here, who, as the counsel of the company, was present at the signing of the agreement, and went with Mr. White and myself the week after to Newfoundland, to obtain the charter, and was our legal adviser through those anxious and troubled years, when success seemed very doubtful. At St. John's the first man to give us a hearty welcome, and who aided us in obtaining our charter, was Mr. Edward M. Archibald, then Prime Minister of Newfoundland, and now for more than twenty years the honored representative of Her Majesty's Government at this port, who is also here to-night. It is a matter for grateful acknowledgment that we were spared to see accomplished the work that we began; and that we meet now, at the end of a quarter of a century, to look with wonder at what has been wrought since in other parts of the world. Our little company came into existence only a few weeks before the Western Union Telegraph Company, which is entitled to share in our congratulations, and has kindly brought a connecting wire into this room, by which we can this evening communicate with every town and village from the Atlantic to the Pacific; and by our sea cables, with Europe, Asia, Africa, Australia, New Zealand, the West Indies, and South America. While our small circle has been broken by death but once, very different has it been with the Atlantic Telegraph Company, which was formed in London in 1856, to extend our line across the ocean. At its beginning there were eighteen English and twelve American directors, thirty in all, of whom twenty-nine have either died or retired from the board. I alone still remain one of the directors. Many of the great men of science on both sides of the Atlantic, who inspired us by their knowledge and their enthusiasm, have passed away. We have lost Bache, whose Coast Survey mapped out the whole line of the American shores; and Maury, who first taught us to find a path through the depths of the seas; and Berryman, who sounded across the Atlantic; and Morse; and last, but not least, Henry. Across the water we miss some who did as much as any men in their generation to make the name of England great—Faraday and Wheatstone, Stephenson and Brunel—all of whom gave us freely of their invaluable counsel, refusing all compensation, because of the interest which they felt in the solution of a great problem of science and engineering skill. It is a proud satisfaction to remember that while the two Governments aided us so generously with their ships, making surveys of the ocean, and even carrying our cables in the first expeditions, such men as these gave their support to an enterprise which was to unite the two countries, and in the end to bring the whole world together. Others there are, among the living and the dead, to whom we are under great obligations. But I cannot repeat the long roll of illustrious names. Yet I must pay a passing tribute to one who was my friend, as he was the steadfast friend of my country—Richard Cobden. He was one of the first to look forward with the eye of faith to what has since come to pass. As long ago as 1851 he had a sort of prophet's dream that the ocean might yet be crossed, and advised Prince Albert to devote the profits of the great London Exhibition of that year to an attempt thus to unite England with America. He did not live to see his dream fulfilled. But though men die, their works, their discoveries, and their inventions live. From that small beginning under this roof, arose an art till then scarcely known, that of telegraphing through the depths of the sea. Twenty-five years ago there was not an ocean cable in the world. A few short lines had been laid across the channel from England to the Continent, but all were in shallow water. Even science hardly dared to conceive of the possibility of sending human intelligence through the abysses of the ocean. But when we struck out to cross the Atlantic, we had to lay a cable over 2,000 miles long, in water over 2 miles deep. That great success gave an immense impulse to submarine telegraphy then in its infancy, but which has since grown till it has stretched out its fingers tipped with fire into all the waters of the globe. "Its lines have gone into all the earth, and its words to the ends of the world." To-day there are over 70,000 miles of cable, crossing the seas and the oceans. And, as if it were not enough to have messages sent with the speed of lightning, they must be sent in opposite directions at the same moment. I have just received a telegram from Valentia, Ireland, which reads, "This anniversary witnesses duplex working across the Atlantic as an accomplished fact"—by which the capacity of all our ocean cables is doubled. Who can measure the effect of this swift intelligence passing to and fro? Already it regulates the markets of the world. But better still is the new relation into which it brings the different kindreds of mankind. Nations are made enemies by their ignorance of each other. A better acquaintance leads to a better understanding; the sense of nearness, the relation of neighborhood, awakens the feeling of brotherhood. Is it not a sign that a better age is coming, when along the ocean beds strewn with the wrecks of war, now glide the messages of peace? One thing only remains which I still hope to be spared to see, and in which to take a part, the laying of a cable from San Francisco to the Sandwich Islands—for which I have received this very day a concession from King Kalakaua, by his Minister, who is here to night—and from thence to Japan, by which the island groups of the Pacific may be brought into communication with the continents on either side—Asia and America—thus completing the circuit of the globe. But life is passing, and perhaps that is to be left to other hands. Many of our old companions have fallen, and we must soon give place to our successors. But though we shall pass away, it is a satisfaction to have been able to do something that shall remain when we are gone. If in what I have done to advance this enterprise, I have done something for the honor of my country and the good of the world, I am devoutly grateful to my Creator. This has been the great ambition of my life, and is the chief inheritance which I leave to my children. 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 40, No. 13, March 29, 1879. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/18866/pg18866-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

Origin and Progress of Ocean Telegraphy

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 . Telegraph Wires Underground. here Telegraph Wires Underground. Philadelphia newspapers report that the American Union Telegraph Company are about to try in that city the experiment of putting their wires underground. The plan works well enough in European cities, and there would seem to be no reason why it should not succeed here, save the indisposition of the companies to bear the first cost of making the change. For some months the Western Union Telegraph Company has had the matter under consideration, but will probably wait until pressed by a rival company before it undertakes the more serious task of taking down its forest of poles and sinking the wires which contribute so much to the prevailing ugliness of our streets. Sooner or later the poles and wires must come down; and it is altogether probable that the change will be beneficial to the companies in the long run, owing to the smaller cost of maintaining a subterranean system. It will certainly be an advantage to the community. 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

Telegraph Wires Underground

Things To Make by Archibald Williams is part of the HackerNoon Books Series. You can jump to any chapter in this book . TELEGRAPHIC APPARATUS. here X. TELEGRAPHIC APPARATUS. The easily made but practical apparatus described in this chapter supplies an incentive for learning the Morse telegraphic code, which is used for sending sound signals, and for visible signals transmitted by means of flags, lamps, and heliograph mirrors. Signalling is so interesting, and on occasion can be so useful, that no apology is needed for introducing signalling apparatus into this book. The apparatus in question is a double-instrument outfit, which enables an operator at either end of the line to cause a “buzzer” or “tapper” to work at the other end when he depresses a key and closes an electric circuit. Each unit consists of three main parts—(1) the transmitting key; (2) the receiving buzzer or tapper; (3) the electric battery. The principles of an installation are shown in Fig. 33. One unit only is illustrated, but, as the other is an exact duplicate, the working of the system will be followed easily. [Illustration: Fig. 32.—Morse alphabet] A wooden lever, L, is pivoted on a support, A. Passing through it at the forward end is a metal bar having at the top a knob, K, which can be grasped conveniently in the fingers; at the other a brass screw, O, which is normally pulled down against the contact, N, by the spiral spring, S. The contact M under K is in connection with the binding post T1 and N with binding post T3; K is joined up to T2, and O to T4. T3 and T4 are connected with one of the line wires; T1 with the other wire through a battery, B; T3 with the other wire through the buzzer, R. [Footnote 1: For the buzzer may be substituted the tapper, described on a later page.] Assuming both keys to be at rest, as in Fig. 33, the two buzzers are evidently in circuit with the line wires, though no current is passing. If the stem of K is depressed to make contact with M, the electric circuit of which the battery, B, forms part is completed, and the buzzer at the other end of the lines comes into action. Since the depression of K raises O off N, the “home” buzzer’s connection with the line wires is broken, to prevent the current being short-circuited. The fact that this buzzer is periodically in circuit, even when the key is being worked, makes it possible for the operator at the other end to attract attention by depressing his key, if he cannot read the signals sent. [Illustration: Fig.33—Telegraphic apparatus; sending key, buzzer and battery] Making the Keys. Transmitting keys can be bought cheaply, but not so cheaply as they can be made. The only expense entailed in home manufacture is that of the screw terminals for connecting the keys with the lines and buzzers. These cost only a penny each, and, if strict economy is the order of the day, can be dispensed with should the apparatus not have to be disconnected frequently. The size of the key is immaterial. The keys made by me have levers 1 inch wide and 5-1/2 inches long, oak being chosen as material, on account of its toughness. K is in each case a small wooden knob on a piece of 3/16-inch brass rod; O a 1-1/2-inch brass screw; A a piece of sheet brass 3-1/2 inches long, marked off carefully, drilled 1/8 inch from the centre of each end for the pivot screws, and in four places for the holding-down screws, and bent up at the ends to form two standards. If you do not possess any brass strip, the lever may be supported on wooden uprights glued and screwed to the base. [Illustration: Fig. 34—Telegraphic apparatus mounted on baseboard] Contact M is a small piece of brass attached to the base by a screw at one end and by T1 at the other. K was drilled near the end to take the short coil of insulated wire joining it to T2, and O was similarly connected with T4. The spring, S, should be fairly strong. A steel spiral with a loop at each end is most easily fitted. Drill holes in the lever and base large enough for the spring to pass through freely, make a small cross hole through the lever hole for a pin, and cut a slot across the base hole for a pin to hold the bottom of the spring. Adjust the lever by means of screw O so that there is a space of about 1/4-inch between K and M when O and N are in contact, and after the spring has been put in position give the screw a turn or two to bring K down to within 1/16 inch of M. This will put the required tension on the spring. The Buzzers.—For these I selected a couple of small electric bells, costing 2s. 6d. each. Their normal rate of vibration being much too slow for telegraphic purposes, I cut off the hammers to reduce the inertia, and so adjusted the contact screw that the armature had to move less than one hundredth of an inch to break the circuit. This gave so high a rate of vibration that the key could not make and break the circuit quickly enough to prevent the buzzer sounding. A Morse Tapper or Sounder. In postal telegraph offices a “sounder,” and not a “buzzer,” is generally used to communicate the signals. Instead of a continuous noise, lasting as long as the key at the transmitting station is held down, the operator at the receiving station hears only a series of taps made by an instrument called a “sounder.” The principle of this simple device is illustrated by the working diagrams in Fig. 35. M is a horseshoe magnet fixed to a base, A. Close to it is an armature, AR, of soft iron, attached to a lever, L, which works on a pivot and is held up against a regulating screw, P1, by the pull of the spring SP. When current passes through the magnet the armature is attracted, and the point of the screw S2 strikes against P2; while the breaking of the circuit causes L to fly back against S1. The time intervening between the “down” and “up” clicks tells the operator whether a long or a short—dash or a dot—is being signalled. [Illustration: FIG. 35.-Elevation and plan of telegraphic sounder.] Materials.—A horseshoe magnet and armature taken from an electric bell provide the most essential parts of our home-made instrument in a cheap form. If these are available, expense will be limited to a few pence. Oak or walnut are the best woods to use for the lever, being more resonant than the softer woods, and for the standard B and stop V. Any common wood is good enough for the base A. The lever L is 6 inches long, 1/2 inch deep, and 3/8-inch wide, and is pivoted at a point 4-1/4 inches from the stop end. The hole should be bored through it as squarely as possible, so that it may lie centrally without B being out of the square. A piece of metal is screwed to its top face under the adjusting screw S1. The spring is attached to L and A in the manner already described on p. 89 in connection with the “buzzer.” The plate P2 should be stout enough not to spring under the impact of the lever. Fig. 36 is an end view of the standard B. The drilling of the pivot hole through this requires care. The screw S2 should be so adjusted as to prevent the armature actually touching the cores of the magnets when attracted. The ends of the magnet winding wire, after being scraped, are clipped tightly against the base by the binding posts T1 T2. If sounders are used in place of buzzers they are connected up with the keys, batteries, and line wires in the manner shown in Fig. 33. Batteries. The dry cells used for electric bells are the most convenient batteries to use. They can now be purchased at all prices from a shilling upwards, and give about 1-1/2 volts when in good condition. One cell at each end will suffice for short distances, or for considerable distances if large conductors are used. If a single cell fails to work the buzzer strongly through the circuit, another cell must be added. [Illustration: FIG. 36.—Standard for sounder.] For ease in transport it will be found advisable to mount key, buzzer, and battery on a common baseboard, which should be provided with a cover and handle. The three parts are interconnected with one another, and the line wire terminals as sketched in Fig. 34. This arrangement makes the apparatus very compact and self-contained. As a finishing touch fit the lid inside with clips for holding a stiff-backed writing pad and pencil for the recording of messages. Lines.—Fencing made of stout galvanized iron wires strung on wooden posts supplies excellent conductors for practice purposes, provided the posts be quite dry. In wet weather there will be leakage. (Fencing with metal posts is, of course, unsuitable, as every post short-circuits the current.) The two wires selected for land lines must be scraped quite bright at the points where the connections are to be made. It is an easy matter to rig up a telegraph line of galvanized wire 1/12 to 1/8 inch in diameter, strung along insulators (the necks of bottles serve the purpose excellently) supported on trees, posts, or rough poles. The length of the line will be limited by the battery power available, but a 6-volt battery at each end will probably suffice for all experimental purposes. A second wire is not needed if one terminal at each end is connected with a copper plate sunk in the ground, or with a metal fence, drain-pipe, etc. 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. Archibald Williams (2005). Things To Make. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/14664/pg14664-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

TELEGRAPHIC APPARATUS

How it Works by Archibald Williams is part of the HackerNoon Books Series. You can jump to any chapter in this book . WIRELESS TELEGRAPHY. here Chapter VII. WIRELESS TELEGRAPHY. The transmitting apparatus—The receiving apparatus—Syntonic transmission—The advance of wireless telegraphy. IN our last chapter we reviewed briefly some systems of sending telegraphic messages from one point of the earth's surface to another through a circuit consisting partly of an insulated wire and partly of the earth itself. The metallic portion of a long circuit, especially if it be a submarine cable, is costly to install, so that in quite the early days of telegraphy efforts were made to use the ether in the place of wire as one conductor. When a hammer strikes an anvil the air around is violently disturbed. This disturbance spreads through the molecules of the air in much the same way as ripples spread from the splash of a stone thrown into a pond. When the sound waves reach the ear they agitate the tympanum, or drum membrane, and we "hear a noise." The hammer is here the transmitter, the air the conductor, the ear the receiver. In wireless telegraphy we use the ether as the conductor of electrical disturbances. Marconi, Slaby, Branly, Lodge, De Forest, Popoff, and others have invented apparatus for causing disturbances of the requisite kind, and for detecting their presence. The main features of a wireless telegraphy outfit are shown in Figs. 59 and 61. THE TRANSMITTER APPARATUS. We will first consider the transmitting outfit (Fig. 59). It includes a battery, dispatching key, and an induction coil having its secondary circuit terminals connected with two wires, the one leading to an earth-plate, the other carried aloft on poles or suspended from a kite. In the large station at Poldhu, Cornwall, for transatlantic signalling, there are special wooden towers 215 feet high, between which the aërial wires hang. At their upper and lower ends respectively the earth and aërial wires terminate in brass balls separated by a gap. When the operator depresses the key the induction coil charges these balls and the wires attached thereto with high-tension electricity. As soon as the quantity collected exceeds the resistance of the air-gap, a discharge takes place between the balls, and the ether round the aërial wire is violently disturbed, and waves of electrical energy are propagated through it. The rapidity with which the discharges follow one another, and their travelling power, depends on the strength of the induction coil, the length of the air-gap, and the capacity of the wires. RECEIVING APPARATUS. The human body is quite insensitive to these etheric waves. We cannot feel, hear, or see them. But at the receiving station there is what may be called an "electric eye." Technically it is named a . A Marconi coherer is seen in Fig. 60. Inside a small glass tube exhausted of air are two silver plugs, p p, carrying terminals, t t, projecting through the glass at both ends. A small gap separates the plugs at the centre, and this gap is partly filled with nickel-silver powder. If the terminals of the coherer are attached to those of a battery, practically no current will pass under ordinary conditions, as the particles of nickel-silver touch each other very lightly and make a "bad contact." But if the coherer is also attached to wires leading into the earth and air, and ether waves strike those wires, at every impact the particles will cohere—that is, pack tightly together—and allow battery current to pass. The property of cohesion of small conductive bodies when influenced by Hertzian waves was first noticed in 1874 by Professor D.E. Hughes while experimenting with a telephone. coherer We are now in a position to examine the apparatus of which a coherer forms part (Fig. 61). First, we notice the aërial and earth wires, to which are attached other wires from battery a. This battery circuit passes round the relay magnet r and through two choking coils, whose function is to prevent the Hertzian waves entering the battery. The relay, when energized, brings contact d against e and closes the circuit of battery b, which is much more powerful than battery a, and operates the magnet m as well as the , which is practically an electric bell minus the gong. (The tapper circuit is indicated by the dotted lines.) tapper We will suppose the transmitter of a distant station to be at work. The electric waves strike the aërial wire of the receiving station, and cause the coherer to cohere and pass current. The relay is closed, and both tapper and Morse inker begin to work. The tapper keeps striking the coherer and shakes the particles loose after every cohesion. If this were not done the current of a would pass continuously after cohesion had once taken place. When the key of the transmitter is pressed down, the waves follow one another very quickly, and the acquired conductivity of the coherer is only momentarily destroyed by the tap of the hammer. During the impression of a dot by the Morse inker, contact is made and broken repeatedly; but as the armature of the inker is heavy and slow to move it does not vibrate in time with the relay and tapper. Therefore the Morse instrument reproduces in dots and dashes the short and long depressions of the key at the transmitting station, while the tapper works rapidly in time with the relay. The Morse inker is shown diagrammatically. While current passes through m the armature is pulled towards it, the end p, carrying an inked wheel, rises, and a mark is made on the tape w, which is moved continuously being drawn forward off reel r by the clockwork—or electrically-driven rollers r1 r2. SYNTONIC TRANSMISSION. If a number of transmitting stations are sending out messages simultaneously, a jumble of signals would affect all the receivers round, unless some method were employed for rendering a receiver sensitive only to the waves intended to influence it. Also, if distinction were impossible, even with one transmitter in action its message might go to undesired stations. There are various ways of "tuning" receivers and transmitters, but the principle underlying them all is analogous to that of mechanical vibration. If a weight is suspended from the end of a spiral spring, and given an upward blow, it bobs up and down a certain number of times per minute, every movement from start to finish having exactly the same duration as the rest. The resistance of the air and the internal friction of the spring gradually lessen the amplitude of the movements, and the weight finally comes to rest. Suppose that the weight scales 30 lbs., and that it naturally bobs twenty times a minute. If you now take a feather and give it a push every three seconds you can coax it into vigorous motion, assuming that every push catches it exactly on the rebound. The same effect would be produced more slowly if 6 or 9 second intervals were substituted. But if you strike it at 4, 5, or 7 second intervals it will gradually cease to oscillate, as the effect of one blow neutralizes that of another. The same phenomenon is witnessed when two tuning-forks of equal pitch are mounted near one another, and one is struck. The other soon picks up the note. But a fork of unequal pitch would remain dumb. Now, every electrical circuit has a "natural period of oscillation" in which its electric charge vibrates. It is found possible to "tune," or "syntonize," the aërial rod or wire of a receiving station with a transmitter. A vertical wire about 200 feet in length, says Professor J.A. Fleming, has a natural time period of electrical oscillation of about one-millionth of a second. Therefore if waves strike this wire a million times a second they will reinforce one another and influence the coherer; whereas a less or greater frequency will leave it practically unaffected. By adjusting the receiving circuit to the transmitter, or , selective wireless telegraphy becomes possible. vice versâ ADVANCE OF WIRELESS TELEGRAPHY. The history of wireless telegraphy may be summed up as follows:— 1842.—Professor Morse sent aërial messages across the Susquehanna River. A line containing a battery and transmitter was carried on posts along one bank and "earthed" in the river at each end. On the other bank was a second wire attached to a receiver and similarly earthed. Whenever contact was made and broken on the battery side, the receiver on the other was affected. Distance about 1 mile. 1859.—James Bowman Lindsay transmitted messages across the Tay at Glencarse in a somewhat similar way. Distance about ½ mile. 1885.—Sir William Preece signalled from Lavernock Point, near Cardiff, to Steep Holm, an island in the Bristol Channel. Distance about 5½ miles. In all these electrical of current was employed. induction 1886.—Hertzian waves discovered. 1895.—Professor A. Popoff sent Hertzian wave messages over a distance of 3 miles. 1897.—Marconi signalled from the Needles Hotel, Isle of Wight, to Swanage; 17½ miles. 1901.—Messages sent at sea for 380 miles. 1901, Dec. 17.—Messages transmitted from Poldhu, Cornwall, to Hospital Point, Newfoundland; 2,099 miles. Mr. Marconi has so perfected tuning devices that his transatlantic messages do not affect receivers placed on board ships crossing the ocean, unless they are purposely tuned. Atlantic liners now publish daily small newspapers containing the latest news, flashed through space from land stations. In the United States the De Forest and Fessenden systems are being rapidly extended to embrace the most out-of-the-way districts. Every navy of importance has adopted wireless telegraphy, which, as was proved during the Russo-Japanese War, can be of the greatest help in directing operations. 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. Archibald Williams (2009). How it Works. Urbana, Illinois: Project Gutenberg. Retrieved https://www.gutenberg.org/cache/epub/28553/pg28553-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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