240 



ELECTKICITY. 



New Thermo - electric Pile. MM. Mure 

 and Clamond describe a new pile in which 

 galena forms the negative element and iron 

 the positive. The galena is cut into bars forty 

 millimetres long and eight millimetres thick, 

 and thin sheet-iron plates fifty -five millimetres 

 long and eight millimetres wide are connected. 

 A series of these is arranged so as to form ^a 

 hollow cylinder, in which a gas-burner is 

 placed. The insulations are formed with thin 

 plates of mica. About forty of these couples 

 produce the intensity of one Bunsen's cell; 

 but it is doubted whether the result affords 

 the electric equivalent of the heat employed. 



Whale -catching ly Electricity. Messrs. 

 Bennett and Ward, London, have patented a 

 method of capturing whales by the agency of 

 electricity, galvanism, or magnetic electricity. 

 A galvanic battery with its coils and necessary 

 accompaniments, or other electrical apparatus 

 of the required intensity, is placed in the boat, 

 or whaling- vessel. Properly-insulated wires 

 are put in connection with, and pass from, the 

 opposite poles or terminals of the battery and 

 along the lines by which the harpoons are se- 

 cured to the boat. The ends of these wires are 

 continued to the points of the harpoons, so that 

 the points shall be in direct communication 

 with the poles of the battery. "When practicable, 

 two harpoons are thrown at the whale at the 

 same or nearly the same time, and when the 

 battery is charged the electric current will pass 

 along the wires to the points of the harpoons, 

 and through the body of the whale, thus com- 

 pleting the electric current. The whale (if 

 the battery and accompaniments are sufficiently 

 powerful) will be paralyzed by the shocks, and 

 will lie at or near the surface of the water, 

 without the slightest motion, so that the boat 

 can approach near enough to spear and cap- 

 ture him without danger. Two harpoons may 

 be bound together, so as to form a single har- 

 poon with two separate barbed points parallel 

 to each other, the two component parts of 

 which are insulated from each other, the wire 

 from each pole of the battery passing down or 

 through either part of the compound-harpoon 

 to the point, thus forming the electric circuit. 

 It is not absolutely necessary that the instru- 

 ment should enter the body of the whale, the 

 same effect being produced if the poles of the 

 battery are in communication with his skin. 

 In the same way electricity may be employed 

 to capture seals, and many other fish and sea 

 or river animals. 



Electro-magnetic Engines on Ship-board. 

 Mr. John Tawse communicates the following 

 statement to The Engineer: 



Some years ago, when in India, I had a boat on one 

 of the salt lakes of the Coromandel coast, and from 

 experiments I then made I became impressed with 



acting upon a comparatively small surface. Also in 

 this case the electric current is deficient in quantity 

 for mechanical purposes. What seemed to be wanted 

 was a very large area of metallic surface, acted upon 

 by an excitant strong enough to evolve a powerful 



lying dormant in the simple and natural galvanic ac- 

 tion of salt water on the sheathing of vessels. Electro- 

 magnetism has hitherto failed as a motive power on 

 the score of economy only. The form of battery 

 used is too expensive, owing to the use of strong acids 



of our scientific Journals. But as I have now worked 

 it out to completion, both by calculation and experi- 

 ment, I detail it herein for the information of your 

 readers. 



A vessel, to be fitted with an electro-magnetic en- 

 gine attached to an ordinary shaft, is sheathed on one 

 side with, copper, and on the other side with zinc. 

 The sheathing is laid on over sheets of gutta-percha, 

 in order to insulate it from the wood-work of the ves- 

 sel. The nails necessary for this purpose are driven 

 in such a manner that they are nowhere in metallic 

 contact with any part of the sheathing. The two sec- 

 tions of copper and zinc sheathing thus form a bat- 

 tery, acted upon and excited by salt water alone. If 

 any one acquainted with the subject will calculate the 

 result of galvanic action on so large a surface as 

 the area of immersion of a floating vessel, he wil" 

 perceive that it is the right application of it alone 

 that is wanted to convert it into a powerful mechani- 

 cal force. 



The vessel being so sheathed, a wire from each sec- 

 tion of course conducts the current to the electro- 

 magnetic engine. In my first experiments I had a 

 large magnet to work a keeper in connection with a 

 crank in the usual way. Since then I have adopted a 

 mode of multiplying the power enormously. Thus 

 the wires are connected with a thick, small-sized 

 electro-magnet in the first instance. In front of its 

 two poles an armature is made to rotate with great 

 velocity, and the augmented current thus produced is 

 carried to an arrangement of two very large magnets 

 working reciprocally in such a way that the keeper, 

 or soft iron beam between them, which works the crank 

 axle of the screw, flows the current into each sepa- 

 rately at every stroke, charging it just before the mo- 

 ment of contact. As regards the wear of the plates, 

 it would be no greater than in the case of ordinary 

 sheathing, with this advantage, that no sea-weed or 

 barnacles would adhere to the sheathing, in constant 

 galvanic activity ; ordinary copper sheathing would 

 be quite free from them if the galvanic circle were 

 complete. In fitting the above engine to a vessel the 

 rotating armature working before the first magnet 

 would have to be driven by a small steam-engine. 



Electric Alarums for Variation of Tempera- 

 ture. MM. Besson and Kneider have invented 

 an apparatus to indicate a fall of temperature 

 in hot-houses and other places where it is im- 

 portant to have a steady degree of heat. It 

 consists of a spirit-thermometer, the bulb of 

 which is placed above, and the tube curved in 

 a U shape. A platinum wire in connection 

 with a battery and ball is carried into the bulb 

 and down to the degree of heat it is desired 

 to notify. Below this minimum the curvature 

 is filled with mercury, which is in free commu- 

 nication with a second platinum wire. As the 

 alcohol contracts with the cold, the mercury 

 will, of course, rise, and, reaching the first 

 platinum wire, complete the circuit, and give 

 the warning. This instrument is intended to 

 be used in connection with what is called the 

 maximum thermometer alarum, which is made 

 by carrying one platinum wire, connected 

 with a battery and bell, into the bulb of a 

 mercurial thermometer, and another wire down 

 the tube to the degree of heat it is not desired 



