Nov. 5, 1885] 



NATURE 



15 



the signs + and - of each section. The wheels l and T 

 of one train, and Li and Ti of the other, are insulated from 

 their trucks and joined by a conductor attached respec- 

 tively to the terminals of the motor M and Mj. A current 

 consequently is always passing from a + section to a — 

 section through each motor. Mechanically then each 

 train is supported by what is practically one continuous 

 steel rod, but in reality at the tops of the posts the rods 

 are electrically subdivided into sections and joined across 

 by insulated wires, one of which may be seen at the top 

 of the posts in Fig. I. The wires connecting the two 

 skeps with the motor, shown in Fig. 4, are not seen in 

 Fig. I, as they were too thin to appear in the photograph 

 from which this figure was taken. To prevent the metallic 

 wheels of the skeps short circuiting the two sections as 

 they cross the tops of the posts, there are insulated gap 

 pieces, which may be seen in Fig. I, at the tops of the 

 posts where the steel rod is electrically divided. 



Various devices have been tried for gripping the rod to 

 obtain the hold necessary to enable the locomotive to 

 haul the train, and these, with many ingenious plans of 

 nest gearing {or economically communicating the power 

 given out by the very quickly revolving electro-motor to 

 the much more slowly moving wheels of the telpher loco- 

 motive, formed the subject of Prof Jenkin's lecture at the 

 Society of Arts in the spring of 1884. Practically, how- 

 ever, it is found that for moderate inclines direct driving, 

 with pitch chains, of two wheels with india-rubber treads 

 gives a gravitation grip sufficiently large for satisfactory 

 haulage ; hence the expense of the locomotive, the com- 

 plexity and wear and tear of its parts combined with the 

 risk of its getting out of order have been all most mate- 

 rially reduced during the last twelve months. 



As the result of the experience gained in the con- 

 struction of the Glynde line, it is estimated that a 

 similar line could now be erected at short notice for a 

 total cost of 1200/., including engine, dynamo, permanent 

 way, and five trains, with locomotives to carry 100 tons 

 daily ; the working expenses, including coal, attendance, 

 and depreciation, being less than yi. per ton per mile upon 

 the material carried. A double Ime like that at Glynde, 

 ten miles long, worked heavily, would carry material at a 

 cost of 2d. per ton per mile, the skeps being empty on 

 their return journey. The larger part of the original cost 

 of the Telpher line is due to dynamos and rolling stock. 

 This plant can be increased, as we are informed, in pro- 

 portion to the work required, so that there is a very 

 moderate increase of cost in the rate per ton per mile for 

 a small traffic, as compared with a larger one. On the 

 other hand, a line constructed for a small traffic will 

 accommodate a much larger one with no fresh outlay on 

 the line itself 



Leaving these facts and figures to speak for them- 

 selves, it now only remains to point out the advan- 

 tages claimed for this system of electric carriage. In 

 the first place the facility with which such a line can be 

 run up and carried over uneven ground or across streams, 

 high fences, and deep ditches, where an ordinary railway 

 would involve serious expense, is sufficiently obvious. A 

 Telpher line need not, as a railway necessarily does, 

 impede the ordinary agricultural operations, but may be 

 carried over fields and pasture lands with little incon- 

 venience. The Telpher line is, moreover, in itself a 

 source of power which can be simultaneously tapped at 

 any desired points and made to assist in the work of 

 agriculture, as the visitors on Saturday had an oppor- 

 tunity of witnessing when, by means of a motor con- 

 nected with the line, a turnip-cutter was put into opera- 

 tion. The possibility of utilising natural sources of power 

 like falling water, and of working the line at great distances 

 from such sources will, as already stated, be evident to our 

 readers. A special advantage claimed for the new system 

 is the ease with which the trains can go round sharp 

 curves without loss of power, since electricity, having no 



momentum, experiences no loss in going round a corner, 

 whereas, with the overhead wire haulage system, as used 

 in Spain and elsewhere, there is both considerable friction 

 and great wear and tear of the running wire ropes where 

 they go round sharp curves. 



The constructors of the Glynde Line are careful to 

 point out that the present line is far from perfect ; un- 

 necessary gradients have been introduced in order to 

 show how the system can be carried over uneven land, 

 and many other improvements have suggested them- 

 selves in the course of their experience, of which ad- 

 vantage would be taken in future undertakings. In face 

 of these disadvantages, the success which marked 

 Saturday's proceedings renders Telpherage, as a system, 

 a very hopeful and cheap method of transference, and the 

 Company is to be congratulated in having taken the first 

 initiative step in this new application of electricity. 

 That Telpherage will ever come into serious competition 

 with the large railways is not intended, for the state- 

 ment made by the Company is to the effect that the 

 function of the Telpher line is not to compete with rail- 

 ways, but to do cheaply the work of horses and carts, 

 light tramways, and the wire rope haulage system, and 

 this, we think, it has a good chance of successfully 

 accomplishing. 



THE MELDOMETER 



THE apparatus which I propose to call by the above 

 name (fxeXSui, to melt) consists of an adjunct to the 

 mineralogical microscope, whereby the melting points of 

 minerals may be compared or approximately determined 

 and their behaviour watched at high temperatures either 

 alone or in the presence of reagents. 



As I now use it it consists of a narrow ribbon of plati- 

 num (2mm. wide) arranged to traverse the field of the 

 microscope. The ribbon, clamped in two brass clamps 

 so as to be readily renewable, passes bridgewise over a 

 little scooped-out hollow in a disk of ebony (4 cm. diam.). 

 The clamps also take wires from a battery (3 Groves cells), 

 and an adjustable resistance being placed in circuit the 

 strip can be thus raised in temperature up to the melting 

 point of platinum. 



The disk being placed on the stage of the microscope 

 the platinum strip is brought into the field of a i" ob- 

 jective, protected by a glass slip from the radiant heat. 

 The observer is sheltered from the intense light at high 

 temperatures by a wedge of tinted glass, which further 

 can be used in photometrically estimating the temperature 

 by using it to obtain extinction of the field. Once for all 

 approximate estimations of the temperature of the field 

 might be made in terms of the resistance of the platinum 

 strip, the variation of such resistance with rise of tempe- 

 rature being known. Such observations being made on a 

 suitably protected strip might be compared with the 

 wedge readings, the latter being then used for ready de- 

 terminations. Want of time has hindered me from making 

 such observation up to this. 



The mineral to be experimented on is placed in small 

 fragments near the centre of the platinum ribbon, and 

 closely watched whiie the current is increased, till the 

 melting point of the substance is apparent. Up to the 

 present I have only used it comparatively, laying frag- 

 ments of different fusibilities near the specimen. In 

 this way I have melted beryl, orthoclase, and quartz. I 

 was much surprised to find the last mineral melt below 

 the melting-point of platinum. I have, however, by me 

 as I write, a fragment, formerly clear rock-crystal, so 

 completely fused that between crossed Nicols it behaves 

 as if an amorphous body, save in the very centre where a 

 speck of flashing colour reveals the remains of molecular 

 symmetry. Bubbles have formed in the surrounding 

 glass. 



