PNEUMATIC COCK. 105 



ed with the greatest accuracy. Mr. Silliman in recomposing 

 water by means or* this instrument, in a manner nearly similar 

 to that which I have pointed out, found it extremely conveni- 

 ent and satisfactory. 



No. XXI. 



AN account of a Cock with two perforations, contrived to obviate 

 the necessity of a vent-peg, in tapping air-tight casks. By Ro- 

 bert Hare, jun. 



GENTLEMEN, 



CONSIDERED merely as an item added to the list of 

 philosophical contrivances the subject of the present commiir 

 nication would without doubt, be too unimportant to merit a 

 place in a volume of your transactions : but I submit it with 

 deference to the judgment of the society, whether as an ad- 

 dition, though a small one, to the comfort and convenience 

 of society at large, it may not obtain a place, to which in 

 any other light it can have no pretensions. 



It is well known that an air-tight cask is usually tapped by 

 means of two apertures, one in the upper part for the admis- 

 sion of air, the other below for the emission of the fluid ; or, 

 in other words, by means of a vent-peg and cock. This me- 

 thod would not be very objectionable, were the vent-peg al- 

 ways firmly replaced as soon as the admission of air becomes 

 no longer necessary ; but this is seldom attended to, and the 

 consequence is the frequent sourness or vapidity of vinous 

 liquors. The quantity of liquor annually spoiled by the omis- 

 sion of vent-pegs must be immense ; and must be particularly 

 great in those families where tapsters are too numerous to be 

 responsible for neglect. 



To obviate these evils, arising from the necessity of a vent- 

 peg, I have contrived a cock. Fig. 1. Plate IV. with two 



Q 



