34 



Snow yields y 1 ^ of water to 1 inch fall in depth ; or 

 a fall of snow of 10 inches in depth on the level would 

 be equal to 1 inch of rain. 



* The following Table and Theorem are from Sir George 

 Shuckburgh, and will show how the Barometer is used 

 for ascertaining the Height of Mountains. 



TABLE I. 



Explanation of Table I. 



This tahle gives the number of feet in a column of 

 the atmosphere equivalent in weight to a like column of 

 mercury T \j of an inch high, when the barometer stands 

 at 30 inches, for every 5 degrees of temperature ranging 



* To perform this operation accurately, two persons should take 

 contemporary observations with two barometers and thermometers, 

 the one at the bottom of the hill and the other at the top. 



