144 ANNUAL OF SCIENTIFIC DISCOVERY. 



ency the bismuth had to alloy with the other metals; but on repeating the experi- 

 ments by tying, instead of soldering the bismuth between the plates, in every 

 case the heat and electric currents traveled in opposite directions. The pieces 

 of bismuth in these experiments were obtained by holding a bar of metal in the 

 flame of a candle until tear-like drops fell, which were received on a smooth 

 surface as discs, to obtain the requisite thickness ; and afterward cut into small 

 pieces from l-40th to 1-5 Oth of a gram. The result arrived at was that the 

 source of the thermo-electric current was at the surface of the joint ; and that 

 to make a thermo-electric battery for practical purposes a contact joint is gen- 

 erally better than a joint by soldering, in which the metals have a tendency 

 to become alloyed, and that in some cases the amount of the electric current 

 is greatly dependent upon the surface of the metals in contact. It is probable 

 that, although experiments on thermo-electricity have yet been productive of no 

 definitively practical results, telegraphic communication may yet be established 

 by the simple agency of a flame of gas. 



ELECTRIC TELEGRAPH IN INDIA. 



"We extract the following notice of the peculiarities of the electric telegraph 

 in India, from a report recently made to the Court of Directors of the East 

 India Company, by Dr. W. B. O'Shaughnessy. He says: 



" The overground lines differ materially from those used in America and 

 England. No wire is used, but a thick iron rod |ths of an inch in diameter, 

 weighing one ton to the mile. The advantages of using thick iron rods are 

 stated to be the following: immunity from damage or fracture by wind or 

 mechanical voiolence ; immunity from injury if accidentally thrown down ; 

 they can not be broken or bent without great trouble ; their mass of metal gives 

 so free a passage to the electric current no insulation is required, the rods are 

 attached to the bamboo posts, etc., without employing glass, porcelain, or any 

 other non-conductor, yet through these lines they work without interruption, 

 during tropical deluges of rain, with miniature batteries consisting of 12 cells of 

 platinum wires and zinc ; no tension is required, as is the case with wire lines 

 the thick rods admit of rusting that would be fatal to a wire line not coated 

 with zinc ; rods (in India) are not more costly than wires. In India it is ne- 

 cessary to use the simplest instruments possible, as they are apt to be deranged, 

 owing to the prodigious electric excitement of the atmosphere, and there are 

 no mechanics at hand in the rural districts. In all the lines running north and 

 south there is a natural current of electricity continually flowing, and this cur- 

 rent deranges the polarity of the needles, confers permanent polarity on soft 

 iron, and produces chemical stains on prepared tissues." 



FARMER'S IMPROVEMENT IN THE TELEGRAPH. 



At the Providence meeting of the American Association, Mr. Moses G-. 

 Farmer, of Boston, gave an account of some improvements recently effected . 

 by him in the electric telegraph, whereby two or more terminal stations can 

 make simultaneous use of the same wire for the transmission of messages. By 



