[ 43° ] 



Sixtb. 



Barometer 30, what is the length of a vertical column of 

 air that weighs as much as V-g- of an inch of mercury = 172,16 

 grains ? 



— 5^=0)05 aiid 30 — ,05=29,9 J. Then log. 3000=477121 



Log. 2995=.476397 



Length = 7,24 fathom, 



which is nearly the half of the weight of -^ of an inch of mer- 

 cury. In this manner, the length correfponding, to any other pro- 

 portional part of an inch of mercury may be found. And reci- 

 procally, the weight being given, the length of the vertical column 

 poffeiTmg that weight may be found, firft feeing whiit proportional 

 part of the weight of an inch of mercury, viz. 3443,2, the given 

 weight makes- ^ = \^^f8s .90! n 



Seventh. 



Barometer 29,5, '^hat is the length of a vertical column of 

 air that weighs as much as one inch of mercury ? 



Here 29,5 — i','l=^'2Bfs- Then log. 295 = 1:1^69822 



Log. 285 r= 4."'48--l-,5 



Length = 149,77 f^'thom. 

 Eighth. 



