114 ANNUAL OF SCIENTIFIC DISCOVERY. 



strata are precisely those which contain the sulphate of zinc, which it 

 is necessary to eliminate. The result is an electric current, which is 

 perfectly constant until the entire disappearance of the zinc, and 

 which is obtained with no more care than that of keeping the reser- 

 voir filled. 



Plis method of uniting a number of pairs is as follows : The stone 

 ware pots in which they are contained, which are three or four diam- 

 eters in length, and consequently have the appearance of tubes, are 

 united and cemented into a bundle or block, which is readily trans- 



tf 



ported from place to place. The upper surface being horizontal, 

 small gutters are employed to convey the acidulated water to each 

 pot. With this arrangement by placing a second reservoir above the 

 pile and altering the nature and elevation of the diaphragm, it is easy 

 to employ a second liquid, which may be made to fall directly drop 

 by drop on the grains of coke, such as nitric acid ; it may be used 

 with advantage when very weak, and when it will no longer serve for 

 the battery of Bunsen, from its ceasing to absorb hydrogen. The 

 liquids on leaving the pots are collected, and may continue to be used 

 until saturation. 



IMPROVED TELEGRAPHIC BATTERIES. 



A SERIES of experiments was recently made on the sub-marine 

 telegraph between England and France, by Mr. Reid, of London, for 

 the purpose of testing a pair of double needle instruments and two 

 new batteries which he had constructed. One of these instruments 

 was placed in the company's office at Dover, and the other in the 

 French office at Calais, with a battery to each. Two of the sub- 

 marine wires were then connected with the instruments, and put in 

 circuit with the batteries. The length of the sub-marine cable in the 

 channel is about 24 miles, and about five miles of land telegraph on 

 each side, making in round numbers a circuit of 68 miles. The bat- 

 tery that was to work this distance formed a strong contrast to the 

 present battery now in use, the length being only 4 inches by 1| deep, 

 and the weight 1 Ib. 5 oz., while the old common battery used on the 

 lines is 36 inches long, 7 inches wide, 8^- inches deep, and weighs 64 

 Ibs. Some of the telegraph clerks in the office smiled incredulously 

 when Mr. Reid connected the miniature battery with the instrument, 

 but were surprised to find the signals to and from Dover and Calais 

 quite equal to the signals they were receiving from their former batte- 

 ries. The next experiment was for the purpose of testing an improve- 

 ment in the double needle instrument, and will require the utmost 

 stretch of faith on the part of our readers to believe. It was as 

 follows : The miniature batteries were removed from the instruments 

 on each side of the channel, and a piece of zinc, three-fourths of an 

 inch square, and a piece of silver to correspond, were then introduced 

 into the mouth of the operator at the office in Dover, and instructions 

 sent to do the same at Calais. The wires, attached to these pieces of 

 metal were then connected with the instruments, and by this simple 



