SCIENCE. 



1 1 



ELECTRICITY. 



An interesting experiment, which seems to have a bear- 

 ing on the action of Edison's friction telephone, has been 

 recently described by Herr Koch. When a plate of plati- 

 num or palladium is polarized by means of an electric cur- 

 rent, the friction of these metals against a plate of moist- 

 ened glass increases immediately. To measure the friction, 

 Herr Koch uses the metal in the form of a hemispherical 

 button, resting on the bottom of a glass cup, filled with 

 pure or acidulated water. The button serves as pivot to a 

 magnetic needle, which oscillates under the action of the 

 earth ; the decrease of the oscillations measures the friction 

 of the pivot. Polarization is produced by the current of 

 the Daniell element, one pole of which communicates with 

 the metallic button, while the other terminates with a plati- 

 num wire entering the water of the cup. The polarization 

 by hydrogen produces no effect, but polarization with the 

 pole oxygenated is found verv efficacious. The friction 

 was increased, through this polarization, in the ratio of 2 

 to 3, and sometimes in that of 2 to 4. This increase of 

 friction appears immediately the circuit is closed, and dis- 

 appears immediately when the current is reversed ; but it 

 disappears slowly, like the polarization itself, when the 

 circuit is merely opened. It increases with the electromo- 

 tive force of the polarization by oxygen. Palladium behaves 

 like platinum. Gold (18 carat) gave no effect. 



M. Desprez has lately attacked the problem of transmit- 

 ting, by means of an electric current, the motion of a motor 

 A to a receiver at some distance B, as a rigid axis between 

 the two would do, so that the angular velocity of B should 

 be always equal in amount and sign to that of A. (The 

 particular case was that of getting within a railway carriage 

 a rotation identical with that of the motor wheels of the 

 locomotive.) On the shaft of the transmitter A are fixed 

 two commutators, each of which reverses the current that 

 traverses it twice each turn ; but the positions of the shaft 

 corresponding to these inversions do not coincide ; they 

 follow each other at intervals of a quarter of a turn. The 

 receiver consists of a permanent magnet or electro-magnet, 

 between the branches of which are two straight electro- 

 magnets, capable of rotating round an axis which coincides 

 with that of the magnet. The currents sent through these 

 electro-magnets from the shaft A produce the desired effect. 

 This apparatus (it is noted) effects the transmission of work 

 of a motor from one point to another with conservation of 

 the angular velocity (which has not been realized in any 

 electric motor hitherto used), the latter varying from o to 

 2,400 turns per minute. The alternating currents required 

 may be generated by a magneto-electric machine. Again, 

 any motion may be considered as the resultant of two 

 movements of rotation ; hence this apparatus, with a simple 

 mechanism added, would serve for transmission of a motion 

 of drawing, or writing. 



The steadiness of the incandescent light over that of 

 the arc has long been understood, but hitherto the cost of 

 the one has been so great that practically it was out of the 

 question for general use. This will account for the little 

 progress made by the Werdermann light. The cost is due 

 principally to the consumption of carbon. Again, it is well 

 known that the consumption of carbon, in an atmosphere 

 containing no oxygen, or in a vacuum, is reduced to a 

 minimum. Many inventors have tried to make lamps to 

 retain a perfect vacuum, but have failed. It is easy, how- 

 ever, to make a water-tight joint, and by surrounding this 

 with water Mr. Brougham has solved one of the problems 

 of the incandescent lamp. The oxygen originally in the 

 lamp globe is quickly exhausted, and then the atmosphere 

 consists of gases which do not combine with carbon, and 

 the result is very slow combustion or disintegration. The 

 water-tight joints having been obtained in the manner 

 above indicated, the globe is partially filled with water, so 

 that when placed over the lamp globe, the water is well 

 over the cap. This water globe is fastened by means of 

 clamps and screws. The inventor states that while the 

 carbon burns away at the rate of six inches per hour in the 

 open air, it burns only one-eighth of an inch perhour when 

 in the water-covered globe. This shows an enormous sav- 



ing in the cost of carbon, and if it can be shown that the 

 saving thus obtained is greater than the cost of the extra 

 power absorbed by the incandescent lamp over that of the 

 arc, a decided step will have been made towards furnish- 

 ing a light that can without difficulty be applied to ordinary 

 sized rooms. We have seen this lamp, and can testify as 

 to its steady light. 



So long as the liquid in the vessel is above the cap of 

 the lamp, no atmospheric air can enter the lamp globe, and 

 at the same time the heat from the lamp is carried off or 

 dispersed and the light diffused. Provision may be made 

 for the removal and replenishing of the liquid in or for 

 causing it to circulate, but we are of the opinion that 

 the ground-glass globe will prove more satisfactory as it is 

 than any addition to the apparatus can make it. We made 

 inquiries as to the liability of the copper wedge to melt, 

 but its size and its connection with so large and such good 

 conductors removes all tendency in this direction. — Elec- 

 trician. 



A simple method of perforating glass with the electric 

 spark is described by M. Fages in a recent number of La 

 Nature. The apparatus required consists (1) of a rectangu- 

 lar plate of ebonite, its size, for a coil giving 12 ctm. sparks, 

 about 18 ctm. by 12 ; (2) of a brass wire passing under the 

 plate and having its pointed end bent up and penetrating 

 through the plate — not farther. This wire is connected 

 with one of the poles of the coil. A few drops of olive oil 

 are placed on the ebonite plate about the point, and the 

 piece of glass to be perforated is superposed, care being 

 taken not to imprison any bubbles of air. The olive oil 

 perfectly accomplishes the object of insulating the wire. 

 One has then only to bring down a wire from the outer pole 

 of the coil, on the piece of glass, above the point of the 

 lower wire, and pass the spark. By displacing the glass 

 laterally for successive sparks, it is easy to make a close 

 series of holes in a few seconds. 



A new form of electric lamp has been invented by Mr. 

 Charles Stewart, M. A. It consists of a number of square 

 carbon rods placed radially upon a disc of wood, or metal, 

 in such a manner that the inner ends of the carbon rods 

 form a complete circle. There is a circular opening in the 

 wooden disc through which the electric light is seen from 

 underneath. The carbons which are all forced toward the 

 centre by a uniform pressure, move forward as they are 

 consumed, and together form the positive electrode of the 

 lamp. The negative electrode consists of a covered hemis- 

 pherical cup of copper which before the current enters the 

 lamp, rests upon the ring formed by the carbons. On the 

 current entering the lamp an electro-magnet raises the 

 metal electrode, and the electric arc is then formed between 

 the circle of carbon and the metal electrode. There is a 

 flow of water through the latter to keep it cool. The inven 

 tor claims for his lamp the following advantages. (1). It is 

 automatic in its action. (2). Burns for a considerable per- 

 iod. (3). Throws no shadows. (4). Simple and inexpen- 

 sive in structure. (5). The intensity of the light may be in- 

 creased if desired. 



The Telegraph and Earthquakes. — A recent letter 

 from Mr. W. A. Goodyear, now director of the governmental 

 mining and geological survey of San Salvador, states that 

 more than 600 shocks of earthquakes were felt there during 

 the last ten days of 1879. They were heaviest about Lake 

 Ilopango, where a shock occurred on the 23rd of December, 

 which broke the telegraph wire asunder and " made the 

 ground on which we stood a perfect network of cracks, 

 opened new springs of water, increased the rivulets in the 

 vicinity to ten times their usual volume, muddied the waters 

 of the lake in many places, and rolled hundreds of thousands 

 of tons of rocks down the steep hills in the form of land- 

 slides." As a sequal to these earthquakes, came the irruption 

 of a volcano in the middle of Lake Ilopango on the night of 

 January 20th to 21st. The volcanic island resulting now 

 measures over five acres in extent, and shoots up a column 

 of steam into the air over 1000 feet in height. This is the 

 first instance we have heard of earthquakes interrupting land 

 telegraph lines, though there are cases on record of their in- 

 1 jerrupting cables. 



