APPARATUS FOR RAISING WATER. 19 



perhaps, in part, by the water in the ciftern not being always 

 of the fame height; for the ciftern did not overflow, but was 

 fupplied with great care, fometimes by a pump, and fome- 

 times by letting water out of a veftel, always keeping the 

 fupply from agitating the contents of the ciftern as much as 

 poffible. Had the bottle been larger, there had probably been 

 more uniformity in the refults of the trials. In eftimation, 

 I think, however, we {hall not overrate the operation of this 

 machine, by taking 13 pints for the mean quantity of effluent 

 water emitted while the bottle was filling with air; and then 

 deducting the quantity expelled from the bottle, it will appear 

 that 20 parts of water carried one of air down the pipe A B : 

 and as one ounce meafure of condenfed air at leafl was col- 

 lected in 14 feconds, fo 16 pints would collect every hour. 



Some few days after thefe experiments, the pipe A B was Trial with a 

 lengthened to 24 feet 7 inches, and D E to 20 feet ; but upon grater length 

 trial, the air was carried into the bottle fo much flower than 

 before, that a fufpicion arofe that fome part of the apparatus 

 was not air-tight ; and on this fuppofition the pipes were 

 taken down. 



In February 1804, the pipes, &c. were examined, and fet I^fs air was ear- 

 up again with confiderable care. AB was 24 feet 7 inches ned down * 

 long; D E, 21 feet one inch ; consequently the difference for 

 the fall was 3 feet 6 inches. With this apparatus, when the 

 diameter of the higher orifice of the pipe D E was four lines, 

 it appeared by four trials (Feb. 25, 1804), that the bottle loft 

 only one ounce of water per minute. 



When the pipe D E was fhortened to 19 feet 7 inches, and 

 had its higher orifice five feet below the furface of the water 

 in the ciftern, four ounce meafures of condenfed air defcended 

 into the bottle, during the emiffion of 16 pints of water, 

 through the orifice at E, when half an inch in diameter. 



The diminution in the collection of air, in thefe laft experi- 

 ments, was much more confiderable than was expected to 

 happen, either from the abforption of the water, or the in- 

 creafed condenfation of the air, which might be occafioned by 

 fo fmall an addition being made to the apparatus. The jet at 

 E was projected more fteadily in thefe laft, than in the pre- 

 ceding trials; and the condenfed air, inftead of rifing into the 

 bottle in large detached bubbles, afcended in a continual ftream, 

 like the evolution of gas from the bottom of an effervefcing 



C 2 mixture. 



