[ 437 ] 



Here loooo feet = 1 666,66 fathom. Andlog. 30 = 477121. 

 And 4771,21 — 1666,66 = 3104,55. 



Now in Sherwin's table I find log. 31045 correfponds with the 

 natural number 20,439 ^^ ^^^^ height, tliercfore the mercury in 

 the upper barometer will (land. 



Problem, II. 



The height of mercury in a barometer on a certain elevation 

 being given, to find the height of the mercury in a barometer at 

 the bottom of that elevation. Mean temperature, 32. 



Solution. 



Convert the feet or inches exprefllng the elevation into fa- 

 thoms, or parts of a fathom. Add thefe fathoms, &c. to the 

 four firft figures of the log. of the number of inches at which 

 the mercury ftands in the upper barometer, the fum will give 

 the logarithm of the height of the mercury in the lower baro- 

 meter, which feek in the table, 



Example. 



The. upper barometer {landing at 20,439 on an elevation of 

 %- Toooo feet, at what height does it ftand in a barometer at the 

 bottom of that elevation. Mean temperature 32° ? , 



Vol. VIII. 3 I Here 



