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Questions and Answers 



This department will appear regularly in THE WORLD'S ADVANCE, subject to following 

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 sideration, although a letter can contain more than one question. On the 10th of the second 

 month preceding the date of issue of the magazine all the questions on hand will be consid- 

 ered and those which are put in the most intelligent manner and of widest general interest 

 will be selected for publication in such issue, the number being governed by the space available. 

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 contain nothing relative to other departments of the magazine. 



DETECTORS. 



(14) R. O. S., Williamstown, Pa., asks: 



Q. i m What size of storage battery is best 

 to use with a one-inch Bull Dog spark coil? 



A. i. We are not familiar with this par- 

 ticular type of coil, but a 6-volt 6o-ampere- 

 hour battery is usually used for a one-inch 

 coil. 



Q. 2. Is the Radioson detector very sensi- 

 tive and reliable? What stations use it? Is 

 it better than the Crystaloi? 



A. 2. We have never tried the type of de- 

 tector mentioned. Better write the makers 

 direct and find out what they have to say. 

 You can also ask them what voltage is neces- 

 sary to be used with their Bull Dog coil. We 

 have tried the Crystaloi detector and have 

 found it very satisfactory for all-around 

 work. 



LIGHT AND POWER FROM BAT- 

 TERIES. 



(15) G. L., Clifton, N. J., asks: 

 Q. i. Is it practicable to install a small 

 electric lighting outfit, for miniature lamps, 

 door bells, etc., in a house remote from a 

 regular supply? 



A. i. Yes, very acceptable and economical 

 installations can be made by use of a few 

 storage cells permanently wired to gravity 

 cells. A satisfactory number of storage cells 

 will be three, for this being common with 

 automobile practice, you will be able to utilize 

 standard appliances. You can make the entire 

 outfit yourself. For storage cells you can 

 make plates of the Plante sort by following 

 the description in the first part of Watson's 

 book on Storage Batteries, the material being 

 ordinary roofing lead. Electrical formation 

 can be hastened by modifying the arrange- 

 ment a little, first separating the strips with 

 toothpicks and filling the intervening space 

 with litharge or red lead, then removing the 

 sticks and fastening the plates together with 

 soft rubber bands. Though these latter will 

 not be very long lived, they will endure until 

 the chemical changes have become well estab- 



lished. Make a dozen gravity cells, using 6" 

 x 8" glass jars, perhaps by removing the tops 

 from bottles. You can cast your own zincs 

 in foundry sand. In order to prevent the 

 zinc salts from creeping over the edges of the 

 jars and to avoid loss from evaporation, you 

 can well adopt the expedient of pouring on 

 top of the solution a layer of paraffin oil, say 

 *4" deep. Also, after the right specific gravity 

 of storage battery solution has been attained, 

 oil in these cells is highly to be recommended. 

 In a warm attic, where you propose to locate 

 the equipment, this is almost your only method 

 of sure operation. We would advise you, 

 however, to put all the batteries in the cellar, 

 and run the wires to the attic. A broken 

 jar will not then result in ruined ceilings and 

 carpets. In use, the gravity cells will regu- 

 larly be charging the storage cells at a slow 

 rate; when apparently drawing from the lat- 

 ter you will really be drawing from both sets 

 in parallel, but almost all the current will 

 come from the storage cells; their low inter- 

 nal resistance permitting them to follow the 

 demand. You will be readily able, with such 

 an equipment, to operate a fan or a sewing 

 machine motor of suitable voltage. 



AERIAL. 



(16) R. A., Dexter, N. Y., asks: 



Q. i. Would an umbrella aerial about 80 

 feet high having about 1,000 feet of wire on 

 it be as efficient as a single wire flat-top aerial 

 2,000 feet long strung on telephone poles 

 about 15 feet high? 



A. i. Yes, the umbrella aerial would be 

 far preferable. 



Q. 2. Please mention one or two wireless 

 stations using a wavelength of 10,000 meters 

 or more. 



A. 2. The Federal Company stations at 

 South San Francisco and Heeia Point, 

 Hawaii, are fitted out to use wavelengths of 

 10,000 and 12,000 meters. Tuckerton, N. J., 

 also uses long wavelengths. The Marconi 

 Company is building stations both on the At- 

 lantic and Pacific coasts which will doubtless 

 use wavelengths of this character. 



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