330 Dr. Andrews on a new Aspirator. 



The neglect of the early history of fluxions v\hich has prevailed 

 in this country, exce})t only as to the controversy, is well illus- 

 trated by the state of the Royal Society's library, as it appears 

 in the catalogue of 1839. Thei-e will be found wanting the 

 Analyst (except in Berkeley's works of 18.20), and most of the 

 tracts which followed it, all the works of Craig, De Moivre's 

 answer to Che\Tie, the first edition of Harris, the folio of Hayes, 

 and even the very celebrated tract of Fatio de Duillier, though 

 it is one of the documents of the controversy with which the 

 Royal Society was afterwards especially concerned. 



October 2, 1852. 



LI. On a new Aspirator, 

 By Thomas Andrews, M.D., F.R.S., M.R.I. A* 



[With a Plate.] 



IN this aspirator the current of air is produced by raising a 

 cylindrical vessel A (Plate III.), open at bottom and immersed 

 in water contained in the outer vessel B. The tube C communicates 

 with the inner and upper part of A. Tlie cords ffff are attached 

 to weights which counterpoise A. In short, the construction is 

 precisely the same as that of the gasometers which are used in 

 the preparation of gas for illuminating purposes on the large 

 scale. In order to raise A, it is connected by means of the brass 

 rod f/i with the free end of the chain of a common one-day Ger- 

 man clock, whose weight, k, is increased so as to enable it both 

 to move the machinery of the clock and also to overcome the 

 resistance of A. By this means the cjdinder A is elevated at a 

 perfectly uniform rate, and which may be varied at pleasure by 

 augmenting or diminishing the length of the clock's pendulum. 

 When the cylinder has attained the proper height, its motion is 

 arrested by the nut /, the clock being at the same time stopped. 

 To prepare for a second operation, the clock weight (/ is removed, 

 the stopcock d closed and e opened ; and by applying a gentle 

 pressure to the top of A, or laying a small weight upon it, A is 

 made to descend till the lower edge rests upon B. t is a, ther- 

 mometer having its bulb inserted in A. 



It is very easy to determine by experiment the precise volume 

 of air whicli enters the receiver A during its ascent ; and if the 

 apparatus be carefully constructed, no appreciable error will arise 

 from inequalities in the volume of an- entering A in different 

 observations. And knowing the height of the barometer and 

 the temperature of the air in A, which gives at the same time the 

 tension of the aqueous vapour, it is easy to calculate the volume 



* Commuiiicated by the Author. 



