Akt. VI. — Be/marks an (he Galvanic Battery. By G. 



W. Hough, Director Dudley Observatory. 1 



[Read before tin- Albany Institute, November, 1868.] 



The constant use of Daniell's battery tor nearly ten years, 

 made us desirous of more fully understanding the mode of 

 its action, and the cause of the decline in the strength of 

 the electric current. For this purpose, during the past 

 year, a series of experiments were instituted, with batteries 

 of various forms. As they were undertaken solely for the 

 purpose of securing the best form of battery for every day 

 use, delicate instruments were not provided, and conse- 

 quently great precision of measurement could not be 

 obtained. 



The Galvanometer consisted of a steel needle one and a 

 half inches in length, attached to a light strip of brass, 

 having a radius of five inches. This needle was mounted 

 horizontally over a coil of silk-covered copper wire. The 

 graduation of the instrument was effected by two methods, 

 viz : by means of the divided current, and by the revolving 

 disk. 



The Rheostat was constructed by winding No. 30 silk- 

 covered wire, around a wooden cylinder ten inches in 

 circumference and 8 inches in length. The coils were 

 separated in different groups, and so connected with 

 switches that any number could readily be Introduced in 

 the circuit. 



For measuring the comparative resistance of different 

 Liquids, two small platinum plates, attached to protected 

 wires, were fastened to a block of wood, and maintained 

 at a uniform distance from each other. 



' Read Nov., 18G8. Abstract read at the Chicago meeting of the American 

 Association. 



