536 



NA TURE 



[Sept. 27, 1888 



verted into a dynamo, and the train could be slowed or stopped 

 by its energy being given up to all the other trains running on 

 the same railway, so that the trains going down hill helped the 

 trains going up hill, the stopping trains helped the starting 

 trains. At that time we suggested detailed methods for carrying 

 out this economical mutual aid arrangement whether the trains 

 were running on the parallel or on the series system. But there 

 is this difference, that, whereas on the parallel system it is only 

 when a train is running fairly fast that it can help other trains, 

 the series system has the advantage that, when a motor is 

 temporarily converted into a dynamo by the reversal of the con- 

 nections of its stationary magnet, the slowing train can help all 

 the other trains even to the very last rotation of its wheels. 

 Brakes that save the power instead of wasting it are of purely 

 English extraction, but their conception has recently come 

 across the Atlantic with such a strong Yankee accent that it 

 might pass for having been born and bred in the States. 



Economy is one feature that gives electric traction the right 

 to claim your attention ; safety is another. This model telpher 

 line worked on " the post head contact" system is so arranged 

 that no two trains ever run into one another, for, in addition to 

 each of the three trains being provided with an automatic 

 governor which cuts off electric power from a train when that 

 train is going too fast, the line is divided into five sections con- 

 nected together electrically in such a way that as long as a train 

 is on any section, A, no power is provided to the section B 

 behind, so that if a train comes into section B, it cannot move on 

 as long as the train in front is on section A. [Three trains shown 

 running on a model telpher line with four automatic locks. ] 

 Whenever a train — it may be even a runaway electric locomotive 

 — enters a blocked section, it finds all motive power withdrawn 

 from it quite independently of the action of signalmen, guard, or 

 engine-driver, even if either of the latter two men accompanied 

 the train, whioh they do not in the case of telpherage : no fog, 

 nor colour-blindness, nor different codes of signals on different 

 lines, nor mistakes arising from the exhausted nervous condition 

 of overworked signalmen, can wiih our system produce a col- 

 lision. Human fallibility, in fact, is eliminated. While the 

 ordinary system of blocking means merely giving an order to 

 stop — and whether this is understood or intelligently carried out 

 is only settled by the happening or non-happening of a sub- 

 sequent collision — our automatic block acts as if the steam were 

 automatically cut off; nay, it does more than this : it acts as if 

 the fires were put out in an ordinary locomotive and all the coal 

 taken away, since it is quite out of the power of the engine-driver 

 to re-start the electric train until the one in front is at a safe 

 distance ahead. 



The photograph now seen on the screen shows the general ap- 

 pearance of the Glynde telpher line, which has recently been much 

 extended in length by its owners, the Sussex Portland Cement 

 Company ; and a telpher line with automatic blocking on the 

 broad principles I have described is about to be constructed 

 between the East Pool tin-mine in Cornwall and the stamps. 

 There will be four trains running-, each consisting of thirty-three 

 skeps containing three hundredweight each, so that the load 

 carried by each train will be about five tons. 



It may be interesting to mention that the last difficulty in 

 telpherage, which consisted in getting a proper adhesion between 

 the driving-wheels of the locomotive and the wire rope, has now 

 been overcome. The history of telpher locomotives is the his- 

 tory of steam locomotives over again, except that we never tried 

 to fit the electric locomotives with legs, as was proposed in the 

 early days for - team locomotives. It is a tedious discouraging 

 history, but it is so easy to be wise when criticizing the past, so 

 difficult to be wise when prospecting the future. Gripping- 

 wheels of all kinds, even the india-rubber tires used for the last 

 three years, have all been abandoned in favour of simple, slightly 

 loose, cheap iron tires, which wear for a very long time, and 

 give a very perfect grip when the bar supporting the electro- 

 motor is so pivoted, pendulum-wise, 'to the framework of the 

 locomotive that the weight of the motor no longer makes the loco- 

 motive jump in passing the posts, as it did until quite recently. 



After several years of experimenting, we have in telpherage, 

 I venture to think, at last a perfectly trustworthy, and at the same 

 time a most economical, method of utilizing distant steam- or 

 water-power to automatically transport our goods, and in time 

 it may even be our people, over hills and valleys, without roads 

 or bridges, and without interfering with the crops or the cattle, 

 or the uses to which the land may be put over which the telpher 

 trains pursue their snake-like way : we have, in fact, the luxury 

 of ballooning, with»ut its dangers. 



SOCIETIES AND ACADEMIES. 



Paris. 

 Academy of Sciences, September 17. — M. Des Cloizcaux 

 in the chair. — Complement to the theory of overfalls stretching 

 right across the bed of a water-course (weirs, mill-races, and the 

 like), by M. J. Boussinesq. In supplement to the theory worked 

 out in the Comptes rendus of July 4, October 10 and 24, 1887, 

 the author here deals with the discharge as influenced by the 

 velocities of the currents at the overfall. — On M. Levy's recent 

 communication on the subject of Betti's theorem, by M. E. 

 Cesaro. This theorem, which plays an essential part in Betti's 

 " Teoria dell' Elasticita," is practically that of Green, which is 

 capable of such manifold applications, and which M. Levy has 

 shown to admit of so many interesting corollaries in grapho- 

 statics. In the present paper M. Cesaro confines himself to 

 proving that the formula of Laplace, giving the velocity of sound 

 in rectilinear elastic mediums, is itself a consequence of Betti's 

 fruitful theorem. — Compressibility of the gases, by M. E. H. 

 Amagat. — On the chlorides of gallium, and on the value of 

 the elements of the aluminium group, by MM. Nilsson and 

 Otto Pettersson. Here are studied the two different chlorides 

 Ga 2 C] fi (or GaCl 3 ) and GaCU, as determined by M. Lecoq 

 de Boisbaudran, the discoverer of gallium. The combinations 

 are also given that are formed with chlorine by the elements 

 of the third group of the natural system, whose chlorides 

 have so far been studied. It is pointed out that aluminium and 

 gallium displace three atoms, indium two, and thallium one of 

 hydrogen of the hydrochloric gas. In this group, with the increase 

 of the atomic weight the elements show an evident tendency to 

 form several combinations with chlorine. — On ferrous chloride 

 and the chlorides of chromium, by MM. Nilsson and Otto 

 Pettersson. The preparation and properties are described of 

 ferrous chloride, and of the two known chromium chlorides — 

 the trichloride, CrCl 3 , and the bichloride, CrCl 2 - — Papers were 

 comjnunicated by M. Rene Chevrel on the great sympathetic 

 nervous system of bony fishes ; by M. Alexandre Vitzou on the 

 incomplete intercrossing of the nerve- fibres in the optic chiasma 

 of the dog ; and by MM. Raphael Dubois and Leo Vignon on 

 the physiological action of para- and metaphenylene-diamine. 



CONTENTS. page 



The Fauna of British India 513 



Our Book Shelf :— 



Stewart and Corry : Flora " of the North-East of 



Ireland" 514 



Letters to the Editor: — 



Electric Fishes.— W. H. Corfield 515 



Sonorous Sands. — H. Carrington Bolton and Alexis 



A. Julien; K 515 



The Late Arthur Buchheim. By Prof. J. J. Sylvester, 



F.R.S 515 



The British Association : — 



Section H — Anthropology. — Opening Address by 

 Lieut. -General Pitt-Rivers, D.C.L., F.R.S., 

 F.G.S., F.S. A. .President of the Section. I. . . 516 



The International Geological Congress 518 



On Crystalline Schists. By Dr. T. Sterry Hunt, 



F.R.S 519 



Some Questions connected with the Problem pre- 

 sented by the Crystalline Schists, together with 

 Contiibutions to their Solution from the Palaeo- 

 zoic Forma-ions. By Prof. K. A. Lossen .... 522 

 On the Classification of the Crystalline Schists. By 



Prof. Albert Heim 524 



On the Origin of the Primitive Crystalline Rocks. 



By A. Michel-Levy 525 



Notes 526 



Our Astronomical Column : — 



Comet 1888 e (Barnard) S 2§ 



Comets Brooks and Faye 5 2 ^ 



Astronomical Phenomena for the Week 1888 



September 30— October 6 529 



Geographical Notes . . . 5 2 9 



Notes on Meteorites. III. {Illustrated.) By J. 



Norman Lockyer, F.R.S 53° 



The Electric Transmission of Power. II. By Prof. 

 Ayrton, F.R.S 533 



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