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Direct-Current Transformation - Fre 5 groups of 5 lamps each in series, or quency and Cycle

25 lamps. They should be connected up Ouestion 1: Will you kindly tell me if there as shown in your sketch, which is enis such a thing as a static direct-current trans- tirely correct. former. If so, please explain its operation.

Question 2: What is the difference between the frequency and the cycle of an alternating current?-W. P. S.

Voltage on Lamps

Question: What kind of conductor should Answer 1: We are not familiar with

be used for carrying electric current for lightany such piece of apparatus as a static ing purposes a distance of 25 miles, and what transformer, or transformer without percentage of wastage should there be ?moving parts, which will transform di- Fi C. W. rect current from one voltage to another. Answer: In this case we should The most common way to change the the use of copper wire, and you could voltage of a direct-current circuit is to allow for a loss of from 7 to 10 per use a motor generator or dynamotor. cent, depending somewhat upon local

Answer 2: A "cycle” is the series of changes which take place in the current or voltage of an alternating-current circuit during the revolution of a simple

Lamps in Series coil in a bipolar field. The current or

Question: If the station transformer were voltage starts first at zero, increases to to burn out, where or how could I get my a maximum in one direction, and falls proper voltage ? Could I get it by connecting to zero, then increases to a maximum 10 lamps in series across the primary mains, in the opposite direction and returns to

the primary voltage being 1,150, and the seczero. By “frequency” is meant the num

ondary 115?-W. H. B. ber of cycles per second.

Answer: If you connected ten 115volt lamps in series across your 1,150-volt primary circuit, then each lamp would

get its proper amount of current and Number of Lights in Series

would glow at normal candle-power, as Question: We have a dynamo for flour the voltage required for a number of

lamps in series is equal to the sum of We are using 4 amperes for flour bleaching. How many 100-volt lights could we run if we

the voltages required by each individual wired them in series of 5; also, is the drawing lamp. Thus in car-lighting, five 110-volt shown below correct?-H. C. D.

lamps are put in series across the 550Answer: If your power for bleaching volt circuit. We would not, of course, requires 4 amperes, you will then have recommend this scheme of putting 10 left 3 amperes of current for supplying lamps across the 1,150-volt mains for your lights. If you use a 16-candle general use; but, as stated, you could obpower incandescent lamp having an effi- tain proper voltage for your lamps in ciency of 372 watts per candle-power, that way. then each lamp would require .56 of an ampere at 100 volts, and you could

Stuttering Telephone Question: Will you please give me the cause and remedy of a telephone stuttering as if some one had short-circuited it? It will cut clear out for a minute or so, and then go all right again. The telephone is of the bridging type.-P. A. J.

Answer: Your trouble is more than likely due to a loose connection. A

swinging short on the line would cause run as many series of lamps as times trouble of this kind, but you should get -56 is contained in 3, which is 5 in round side tone, otherwise line connections or numbers. You could accordingly run instrument wiring are in trouble.


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VIVE thousand dollars invested in an Arrow car brings a better return for the money than twice K that amount invested in a foreign car. The prestige of foreign cars, aside of course from admitted

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Wireless Telegraphy: Its History, Theory, and

Practice. By A. Frederick Collins. Cloth. Wustrated.
Pages 300, 6 by 9 inches. Published by McGraw Pub-

lishing Co., New York. Price, $3.00. This book should prove a welcome and valuable addition to the present literature on Wireless Telegraphy, about which so. little is generally known, and yet to which such a live interest is attached. The author is a man who has had a great deal of practical experience in the wireless field, and has presented the results of his investigations in a concise and understandable manner, with numerous illustrations.

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Twenty-five different kinds of wavedetectors are fully explained and illustrated. All the different systems worthy of notice are taken up ; and their different parts—such as the transmitter, receptor, etc.—are described with diagrams and half-tone illustrations. Among the topics treated may be mentioned: Ether, Electric Waves, Disruptive Discharge and Oscillators, Induction Coils, Interrupters, Detectors, Transmitters, Receptors, and Syntonization. The book ends with a chapter on Wireless Telephony.

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Mention Technical World Magazine

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LITERATURE-(Continued) Forge Practice. By John Lord Bacon. Instructor in Forge

Work, Lewis Institute, Chicago. Cloth. Illustrated. 258 Pages, 71-4 by 5 inches. Published by John Wiley

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The Polariscope in the Chemical Laboratory. By

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