1916 ad: Selenium Cells

. Monday, July 1, 2013

Selenium Cells. Made in America. For eleven years we have been the largest distributors of selenium cells in the world. We have actually sold more such cells than all other houses combined. Before the European War broke out we had been selling the well-known Gripenberg cell exclusively, but inasmuch as this cell is an imported one, we have not been able to secure it for nearly a year. We now present for the first time in history a wonderful American Selenium Cell, much more efficient than any cell ever handled by us. It will rank high in electrical circles as it has several valuable points not usually found in such cells. We unhesitatingly recommend it and stand back of all our claims. Our illustration shows the full size of the cell. It is built in form of a watch and is entirely foolproof. There are no screws, no loose wires -- nothing to get out of order. The over-all size is 1 1/2" x 1 1/4". The selenium surface is protected by glass and can therefore not be injured, even if roughly handled. The active selenium surface measures 3/8" in diameter -- a very large surface and much larger than found in the best cells. The current is supplied to the cell by means of two net binding posts. The metal case is nickel plated. The ratio of these cells is remarkable. Thus a typical cell in the dark measures 96,000 ohms, while if exposed to a 40 c.p. tungsten lamp, the resistance drops to 12,000 ohms. This is a ratio of 8 to 1 which is remarkable and bespeaks of the high quality of the construction. Every cell is guaranteed and we will replace any not giving satisfaction. Important. When ordering state if you wish a high resistance or a low resistance cell. We have a large supply on hand. Immediate shipments. Orders filled within 24 hours. No. 517 Selenium Cell as described each $5.00 by registered mail extra 12 cents. No. 715 Built-up Selenium Cell (1 million ohms. Ratio of 30 to 1) Works on 110 volts. Price each $7.00. No. 716 Special Vacuum Selenium Cell (Resistance can be hand from 5,000 to 500,000 ohms). Price $10.00. "The livest catalog in America" 1/2 inch thick. Weight 1/2 pound. 658 illustrations. What catalog No. 16 contains. It contains the largest assortment of wireless and electrical experimental apparatus shown in any catalog published. In addition are shown commercial wireless sending and receiving outfits, electric motors, dynamos, flashlights, medical batteries, high frequency apparatus, plating outfits, toys, printing presses, tools, sporting goods and the largest scientific book section published. This book will give you as much information as many books that cost you $1.00 or more. It contains 658 illustrations, 2,000 articles, complete code chart of Morse, continental and navy codes, 16-page "Treatise on Wireless Telegraphy" list of call letters of U.S. Government and commercial ship and shore wireless stations, besides a great many useful tables and formulas. This valuable book is 7 x 5 1/4 inches in size and 1/2 inch thick and wll bound. It is sent free for 4c to cover postage only. Some questions answered in cyclopedia Catalog No 16: The wireless law of August 13, 1913. How to receive wireless messages. How far you can telephone by wireless. Wave lengths of principal radio stations. How to erect a wireless aerial. How to receive time by wireless. How to photograph electrical discharges. How to experiment with spark coils. How to test storage batteries. How to make Tesla Experiments. Call letters of all commercial and government wireless stations. Electro Importing Co. 236 Fulton Street, New York City.

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