4;^ TIMEKEEPERS* 



D€s«riptioa « made to beat half seconds, the balance making 240 vi- 

 and effects of brations both ways in a minute. For if the balance wheel 

 SipemeS^'as has 15 teeth, the fourth wheel 80 teeth, and the balance 

 constructed by Jj^Iqj^ IQ t^eth, there will be 120 beats, or half seconds, in 

 Arnold. *^ 



one minute. 



It is also made with the escapement wheel of 12 teeth, 

 the balance pinion having 7, and the fourth wheel 70 5 con- 

 sequently there will be 120 beats, or half seconds, in one 

 minute as before. It has been already remarked that the 

 pallat for 12 teeth must be half the diameter of the wheel, 

 and for 15 teeth five-twelfths, or fifty degrees. 



The pocket timekeepers, that they may not be disturbed 

 by motion, have what is called a quicker train, the seconds 

 hand making 150 beats upon the dial, or 5 beats in two 

 seconds. The escapement wheel has 15 teeth, the balance 

 pinion 8 teeth, and the fourth wheel 80, consequently there 

 will be 1 30 beats in one minute. The pallat being 50 degrees 

 in diameter, measured upon the diameter of the balance 

 — wheel. 



No mention has been made of the numbers of the teeth 

 in the other wheels and pinions, as they are of little or no 

 importance, and may be varied considerably. 



vm. 



An Essai) on the Cohesion of Fluids. Bi) Thomas Youno 

 M.D. For. Sec. R.S.* 



I. General Principles. 



General pti net- It has already been asserted, by Mr. Monge and others, that 

 hSon otfluX the phenomena of capillary tubes are referable to the cohesive 

 attraction of the superficial particles only of the 'fluids em- 

 ployed, and that the surfaces must consequently be fonned 

 into curves of the nature of hntearia, which are supposed to be 

 the results of a uniform tension of a surface, resisting the pres- 

 sure of a fluid, either unifoi'm, or varying according to a givcr^ 

 'law. Segner, who appears to have been the first that Maintained 



■> Philos, Trans. 1805. 



