286 Dr. Hare's Description of Voltaic Series, &fc. 



couronne des tasses, or pile of Volta. The Cruickshank troughs 

 were superseded by Babbinglon's apparatus, having cells made in 

 troughs of porcelain, or in mahogany troughs with glass partitions, 

 the plates being attached to a bar by which ten or twenty might be 

 lifted at once from the acid, so as to suspend its reaction with the 

 zinc. It is to this characteristic, that the preference given to the last 

 mentioned construction by Davy and others has been ascribed. It 

 occurred to me that the quadri-rotary mechanism, being applied to 

 the Cruickshank trough, would completely obviate the difficulty of 

 suspending the chemical reaction, which had led to the abandon- 

 ment of this construction of the series, and likewise that the saving 

 which had been alleged to follow from the surrounding of the zinc by 

 copper, could be equally secured by the Cruickshank pairs. As in 

 these the copper and zinc afford reciprocal support, the zinc might 

 be of less than half the thickness requisite in isolated plates, and two 

 of the former might be put in less space than one of the latter. In 

 either case there would be the same surface subjected to oxidize- 

 ment, since one of the surfaces of each zinc plate in the Cruickshank 

 pairs is protected ' from the acid. It was ascertained that at least 

 three Cruickshank pairs could be introduced within an inch, so that 

 more surface could be exposed in a given space in this way, than in 

 any other. Since that time a small trough has been constructed in 

 which sixty pairs were introduced within ten inches and a half. 



The advantages of this construction are as follows : the associa- 

 tion of the two metals into one compound plate, renders them both 

 firmer so as to admit of greater evenness of surface and more exact 

 parallelism, and consequently of greater proximity without contact: 

 the soldering being once made need not be disturbed in order to re- 

 move and clean the plates : the communication between the plates 

 of zinc and copper is more ample and less liable to fail. 



The method of making the grooves to which I resorted, is as fol- 

 lows ; a plough plane must be so arranged as to have the distance 

 between the cutting iron and guide plate equal to that required for 

 the interstices between the plates. A wooden board is to be pro- 

 cured of about from three eighths of an inch to half an inch in thick- 

 ness, according to the proposed size of the trough, and sufficiently 

 wide, when slit, to form the bottom and sides of a box to contain the 

 pairs. In this board the grooves are made by running the guide 

 plate in one groove, while another groove is made by the cutting 

 iron. Afterwards the board being slit, so as to make the sides and 



