April 5, 1889.] 



SCIENCE. 



259 



This oscillation of the current was first observed by Joseph Henry, 

 in 1842. He found that when the wire joining the two coatings of 

 the jar was bent into a helix, and a needle placed inside, the mag- 

 netization of the needle due to the discharge-current was not al- 

 ways in the right direction. Henry stated that " the phenomenon 

 requires us to admit the existence of a principal discharge in one 

 direction, and then several reflex actions backward and forward, 

 each more feeble than the preceding, until equilibrium is obtained." 

 Later, Thomson worked out a mathematical theory of the subject, 

 which agreed with Henry's observations ; and further experiments 

 have substantiated the results 



Professor Lodge showed experimentally, but on a small scale, a 

 case of the resonance of two Leyden-jar discharges, by causing 

 sparks in one circuit by the discharge of a jar in a neighboring 

 one. Another interesting experiment was the rendering audible of 

 a Leyden-jar discharge as a musical note. The period of the 

 oscillation in an ordinary discharge is many million vibrations a 

 second. But this can be reduced in two ways, — by adding to the 

 capacity of the circuit ; or by increasing its self-induction, as one 

 would increase the flexibility of a spring, and then load it in order 

 to increase its period. On adding more jars, and on increasing the 

 self-induction of the circuit by putting in a coil of wire, the period 

 was reduced until a shrill whistle resulted from the discharge ; on 

 adding another coil, the one lowered again until the pitch was 

 about that of the highest note of a piano ; another coil brought it 

 down to the octave above the middle C. The noise of the spark 

 which is ordinarily heard is due to the sudden heating of the air. 

 If the heat is oscillatory, the sound will be oscillatory too ; and, by 

 reducing the period of the electric oscillation, we bring the sound 

 within the limit of audibility. On analyzing the spark that pro- 

 duced the lowest note, by means of a rotating mirror, a coarsely 

 serrated band was seen. Another interesting experiment was tried 

 with the jar discharge. If a polarized ray of light be passed 

 through a piece of heavy glass around which a current is passed, 

 the plane of polarization is rotated. Instead of a steady current. 

 Professor Lodge used the oscillatory current from the jar ; and a 

 similar effect was obtained, even when the period was less than 

 one seventy-thousandth of a second. 



In concluding, Professor Lodge said, " The present is an epoch 

 of astonishing activity in physical science. Progress is a thing of 

 months and weeks, almost of days. The long line of isolated rip- 

 ples of past discovery seem blending into a mighty wave, on the 

 crest of which one begins to discern some oncoming magnificent 

 generalization. The suspense is becoming feverish, at times almost 

 painful. One feels like a boy who has been long strumming on 

 the silent keyboard of a deserted organ, into the chest of which an 

 unseen power begins to blow a vivifying breath. Astonished, he 

 now finds that the touch of a finger elicits a responsive note ; and 

 he hesitates, half delighted, half affrighted, lest he be deafened by 

 the chords which it would seem he can now summon forth almost 

 at will." 



A New Alloy. — A new alloy has been made by Herr Reith 

 of Bockenheim, Germany, which is said practically to resist the 

 attack of most acid and alkaline solutions. Its composition is as 

 follows: copper, 15 parts; tin, 2.34 parts; lead, 1.82 parts; anti- 

 mony, I part. The alloy is therefore a bronze with the addition of 

 lead and antimony. The inventor claims that it can be very ad- 

 vantageously used in the laboratory to replace vessels or fittings of 

 ebonite, vulcanite, or porcelain. 



A Series Electric Tramway in England. — There has 

 recently been tried, near the Northfleet Station of the South-East- 

 ern Railway in England, an experiment on a system of electric 

 traction, which, in its practical realization, has been imported from 

 the United States. Indeed, it is curious that while the English 

 technical papers claim with some pride that the work is a " dis- 

 tinctly English invention, due to the late Professor Jenkin and Pro- 

 fessors Ayrton and Perry," yet the invention apparently lay dor- 

 mant until it was practically worked out by two Americans, — 

 Short and Nesmith, — applied on an extended scale in the United 

 States, and finally introduced into England by the corporation 

 controlling their patents. The track used for the trial seems to 

 be considered a specially difficult one, since it has on it a three- 



per-cent grade four hundred yards long ; but if we compare it with 

 the average line in this country, where eight and even ten per cent 

 grades are the rule rather than the exception, it would seem a very- 

 easy trial. The car was propelled by a single motor, sleeved la- 

 the axle and flexibly suspended, according to the system introduced 

 by Sprague. Current was supplied from a conductor carried in a 

 conduit. The novel feature of the system lies in the fact that the 

 cars are worked in " series " instead of in " parallel." This neces- 

 sitates the interposition of the motors into the main line ; and to 

 effect this a special device is needed. In the main line, in the 

 centre of the conduit, are a number of contacts made by two plates 

 normally held together by springs. If these plates were pulled 

 apart, the main circuit would be broken, unless at the same time 

 some conducting circuit is joined across them. Attached to the 

 car, and travelling in the conduit, is a long " arrow." There are 

 metallic strips on either side of the " arrow," and between these 

 strips is joined the circuit of the motor. As the car moves along,^ 

 the " arrow " passes between the contact-plates, forcing them 

 apart, and thereby introducing the motor into the main circuit. 

 On passing through a distance equal to the length of the " arrow," 

 another set of contact-plates is forced apart, while the set which is 

 left closes, thus keeping the circuit intact. On the trial the system 

 worked well, and every one was well satisfied, as is usually the 

 case at an exhibition of a new system. It should be remembered, 

 however, that in this country the system has not been uniformly suc- 

 cessful. At Denver a great deal of trouble was experienced, to 

 the detriment of electric traction in that section of the country, and 

 the system is not being rapidly introduced. The large number of 

 contacts required, the possibility of some of them failing, the great 

 danger of burning out the motors, with other possible objections, 

 tend to make an unfavorable comparison with systems of greater 

 simplicity. 



The Price of Copper. — The collapse of the copper syndicate 

 should have an excellent effect on the extension of electric lighting: 

 and power distribution. The high price that has ruled in the last 

 year has been very unfavorable to electric-light people, especially 

 those using the low-tension system of distribution. It is to be- 

 hoped, however, that the change in the cost of copper will not 

 bring up again the fierce discussions as to the relative merits of 

 high and low potential distributions which ruled about a year ago. 

 We can expect, however, that this year will see more than double 

 the amount of plant installed than did last year. 



NOTES AND NEWS. 



Several large textile manufacturers of Paterson and other 

 manufacturing centres are reported by Bradsireet's to be inaugu- 

 rating a movement for the founding of a textile technical school. 

 The object of the movement is threefold, — to elevate the char- 

 acter and improve the style of the American fabrics, to render the 

 domestic manufacturers independent of European art and skill in 

 the production of high-grade goods, and to secure independence of 

 trades-unions. Negotiations are reported to have already been 

 opened with qualified teachers from abroad to assume charge. 



— As summer approaches, and so many of our readers are con- 

 sidering the possibility of spending some of their vacation time in 

 Europe, it may be well for them to investigate the merits of the 

 Cheque Bank as a custodian of their funds while travelling. This 

 institution was established seventeen years ago in London, for the 

 convenience of the travelling public, and numbers among its trustees 

 some well-known men. The bank aims to furnish the traveller 

 with an immediately available security equal in value to a Bank of 

 England note, only safer to carry. Letters of credit are done away 

 with, while upwards of two thousand banks and bankers through- 

 out Europe are now cashing the checks issued by the Cheque Bank. 

 The British Government accepts them in settlement of customs 

 charges, and railroad companies frequently accept them in payment 

 of fares, as do also hotels and store-keepers in some cases. The 

 bank issues check-books, each containing ten checks, which can be 

 drawn for any amount the purchaser may desire. A branch office 

 has recently been opened in New York under the management of 

 Messrs. E. J. Mathews & Co., at No. 2 Wall Street. 



