NATURAL PHILOSOPHY. 167 



The third part of this invention consists in covering the tele- 

 graph-wire itself, at the point of support, and for a distance of a 

 foot or more on each side, with a covering of hard rubber, similar 

 to that placed on the insulator. This is carried into effect in the 

 following manner, namely ; first, pieces of ordinary galvanized 

 telegraph-wire are tinned, and then covered with hard vulcanite, in 

 the same manner that the insulated pins are covered, as above 

 described ; secondly, these pieces of wire are spliced into the 

 telegraph-wire at each point of support by means of the usual 

 soldered joints. Prior to being used, these pieces are boiled in 

 paraffine wax, and, from time to time, when their surface becomes 

 damaged by the solar actinic raj's and exposure, they are washed 

 and rubbed with paraflSne oil or coal-tar naphtha, which renews 

 the insulating power of the surface. 



These insulators are principally useful where the wires are ex- 

 posed to the spray of the sea, the rain washing them clean. This 

 oil is very useful with all kinds of insulators, for the purpose of 

 renovating the surface. — Scientific American. 



ELECTRIC MARINE BUOYS. 



M. Emile Duchemin has been for several years engaged in ex- 

 perimenting on the ocean as an electric agent, and has recently 

 arrived at results which may turn out to be important, and which 

 are certainly interesting. The object in view is the construction 

 of a marine pile which shall give a constant current of electricity 

 as long as the elements last. He tried at first with copper and 

 zinc, but the result was not satisfactor}' ; the gas produced some- 

 times left a non-conducting substance on the surface of the copper, 

 and a polarizing action set in which threatened failure. Lately 

 M. Duchemin has substituted a cylinder of retort-charcoal for the 

 copper, with a plate of zinc suspended in the interior, the whole 

 being connected by a cross-piece of wood, and buoyed by means 

 of cork floats. Several of these piles were thrown into the basin 

 at Fecamp, and the results are thus described by the inventor : 

 "At the extremity of two conducting wires I could produce 

 sparks, and during two months this new electrical generator 

 worked an electrical bell without cessation until a Norwegian ves- 

 sel by accident destroyed the buoy." 



Further experiments led M. Duchemin to the conclusion that by 

 multiplying the number of piles he could increase not only the 

 quantity but the tension of the electric current. This was an un- 

 expected result, and in a certain degree in opposition to the expe- 

 rience of the laboratorv : but, as M. Duchemin savs, the sea is a 

 basin differing from those used in lal)oratories : the immensitv of its 

 extent, the chemical composition of its water, its incessant motion, 

 all point to the probability of new laws to be studied. The nature 

 of the water of the ocean mav exercise a great influence on our 

 planet, and the study of this may possibly change our received 

 ideas respecting the currents which atfect tiie compass. Admitting 

 that the vast basins of the sea are in contact with land containing 



