Direct-Current Transformation - Fre quency and Cycle Question 1: Will you kindly tell me if there is such a thing as a static direct-current transformer. 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. Answer 1: We are not familiar with any such piece of apparatus as a static transformer, or transformer without moving parts, which will transform direct current from one voltage to another. The most common way to change the voltage of a direct-current circuit is to use a motor generator or dynamotor. 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 coil in a bipolar field. The current or voltage starts first at zero, increases to a maximum in one direction, and falls to zero, then increases to a maximum in the opposite direction and returns to zero. By "frequency" is meant the number of cycles per second. Number of Lights in Series Question: We have a dynamo for flour bleaching-500 volts, 31⁄2 K. W., 7 amperes. We are using 4 amperes for flour bleaching. How many 100-volt lights could we run if we wired them in series of 5; also, is the drawing shown below correct?-H. C. D. Answer: If your power for bleaching requires 4 amperes, you will then have left 3 amperes of current for supplying your lights. If you use a 16-candlepower incandescent lamp having an efficiency of 32 watts per candle-power, then each lamp would require .56 of an ampere at 100 volts, and you could run as many series of lamps as times .56 is contained in 3, which is 5 in round numbers. You could accordingly run 5 groups of 5 lamps each in series, or 25 lamps. They should be connected up as shown in your sketch, which is entirely correct. Voltage on Lamps Question: What kind of conductor should be used for carrying electric current for lighting purposes a distance of 25 miles, and what percentage of wastage should there be ?F. C. W. Answer: In this case we should advise the use of copper wire, and you could allow for a loss of from 7 to 10 per cent, depending somewhat upon local conditions. Lamps in Series Question: If the station transformer were to burn out, where or how could I get my proper voltage? Could I get it by connecting Io lamps in series across the primary mains, the primary voltage being 1,150, and the secondary 115?-W. H. B. 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 would glow at normal candle-power, as the voltage required for a number of lamps in series is equal to the sum of the voltages required by each individual lamp. Thus in car-lighting, five 110-volt lamps are put in series across the 550volt circuit. We would not, of course, recommend this scheme of putting 10 lamps across the 1,150-volt mains for general use; but, as stated, you could obtain proper voltage for your lamps in that way. 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 trouble of this kind, but you should get side tone, otherwise line connections or instrument wiring are in trouble. F This is a rather good picture of the Great Arrow Victoria Tonneau, 40-45 IVE thousand dollars invested in an Arrow car brings a better return for the money than twice that amount invested in a foreign car. The prestige of foreign cars, aside of course from admitted good car construction, is due to a certain sense of pride and satisfaction in owning an imported and expensive car. Every American gentleman who considers his investment in a touring car on the basis of the best return for the money will, on investigation, be convinced that the Arrow will give him more for its cost than any foreign car made. The Arrow is the highest-priced American car made. But as the American motorist learns to discriminate, he will consider the additional price a good investment when it saves both expense and worry. The chief expense of a motor car is the cost of running it. The record of the Great Arrow, in the Glidden Trophy Tour, of one thousand miles without a single adjustment, is not a phenomenal performance for the Arrow. It is something which any American gentleman, not an expert chauffeur, can duplicate with a Great Arrow car. The Arrow, built by Americans, for American roads, American conditions and the American temperament, offers more to the non-professional American gentleman who looks to his car for enjoyment and pleasure instead of glory and expense than any other car made, foreign or domestic, high-priced or low-priced. THE GEORGE N. PIERCE CO., Buffalo, N. Y. LITERATVRE REVIEWS MAGAZINES BOOKS BOOKS RECEIVED Wireless Telegraphy: Its History, Theory, and Practice. By A. Frederick Collins. Cloth. Illustrated. Pages 300, 6 by 9 inches. Published by McGraw Publishing 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. Both the expert and the layman should find that this book contains much of interest and of value to him. A chapter is devoted to practically every important topic which comes under the head of wireless telegraphy. Each topic is treated, first of all, historically; its theory is then taken up from a mathematical and physical standpoint. An experimental investigation is likewise included, as well as the discussion of the practical operation of the apparatus. The chapters on the induction coil are particularly interesting, one discussing it from the theoretical standpoint, and the other being devoted to the construction of coils from a 2-inch spark up to the largest sizes giving a spark especially adapted to wireless transmission. 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. Mention Technical World Magazine Most Liberal Cigar Proposition Ever Made All the time you have been paying ten cents over the counter for a Panetela cigar, we have sold our FEDORA Panete la, a cigar of exactly the same value, at 4c. In fact it was one of our standard brands that we sold successfully for many years to the leading jobbers at $40 per thousand. But, as you know, our method was changed a long time ago and we came direct to smokers with our entire product at the same jobbers prices. Altogether here is our FEDORA PANETELA: GUARANTEED superior to any $5.00 per hundred Panetela advertised, though the price is 20% less. GUARANTEED superior to the 10c cigars sold by dealers. GUARANTEED to be made of pure Havana filler and high-grade Sumatra wrapper. GUARANTEED to be made in the cleanest of factories; to be absolutely free from any kind of flavoring matter. GUARANTEED to SAVE HALF YOUR CIGAR MONEY, sometimes more, in comparison with regular retail prices. GUARANTEED to please you or the trial costs you nothing. OUR PROPOSITION-For $4.00 we will send you 100 FEDORA Panetelas and our beautiful cigar catalogue, "Rolled Reveries," that "tells you all about it." ALL TRANSPORTATION CHARGES PREPAID. Smoke as many as you wish to find out whether they suit you or not. If not, or on comparison you don't think our claims are carried out, return what you have left, at our expense, and we will REFUND EVERY CENT. The same proposition applies to 50 FEDORA Panetelas at $2.00. We do not sell cigars on credit, but we do guarantee your perfect satisfaction. Our strictly cash business saves bookkeepers' salaries, clerical work, makes no bad debts, and our customers get the benefit in value. Photo of FEDORA Panetela Exact Size IF YOU PREFER, we will send you an assortment of other brands of cigars, showing fifteen 10c. values, ten 5c. values for $1.00. Each separately wrapped and described. Same guarantee of MONEY BACK if not satisfied. Our Booklet, Rolled Reveries, sent free on request. ORDER NOW, stating color and strength wished. LITERATURE-(Continued) Forge Practice. By John Lord Bacon. Instructor in Forge Work, Lewis Institute, Chicago. Cloth. Illustrated. 258 Pages, 7 1-4 by 5 inches. Published by John Wiley & Sons, New York. Price, $1.50. THIS Volume is compiled from the notes used by the author in teaching this subject to classes at the Lewis Institute; and it has, therefore, stood the test of actual use. It is not intended to take the place of shop experience, but rather to supplement it in order that the work may be done in the most intelligent manner. Forging is essentially a practical subject, and requires manual skill to a high degree; but the progress of the worker will be much more rapid if this skill be coupled with an intelligent understanding of the underlying principles on which the processes of forging depend. This subject is treated in a logical manner, the following topics being among those taken up: General Description of Forge and Tools, Welding, Calculation of Stock, Forge Operations, Steam Hammer Work, Duplicate Work, Metallurgy of Iron and Steel, Tool Steel Work, Forging and Tempering, Miscellaneous Work. Under the subject of "Welding" are taken up the common types of welds, and the best method of making them is discussed. Another feature of the book is its treatment of "Calculation of Stock" for bent shapes, as well as for general forging. The chapter on "Tool Steel Work" is perhaps especially interesting and discusses the processes of hardening, tempering, different hardening baths, spring temper, annealing, etc. Numerous tables which should be useful to the blacksmith, may be found at the end. The book is profusely illustrated and well indexed. The Polariscope in the Chemical Laboratory. By Geo. Wm. Rolfe, A. M., Instructor in Sugar Analysis, Massachusetts Institute of Technology. Cloth. Pages 320, 5 by 71-2 inches, Illustrated. Published by the Macmillan Co., New York City. Price $1.90. THE importance and extent of the sugar industry has brought the polariscope into extensive use, and it has developed into an instrument of high efficiency in sugar testing. The author, who has had experience covering nearly twenty years as technical chemist in the sugar houses of the West Indies and in the glucose industries of the West, has written this book Mention Technical World Magazine |