Mr Galbraith's Barometric Measurements of Heights. 325 



A, and the latter by B, the succeeding observations were made 

 at Edinburgh, after standing together during the night, and ojn 

 the top of Carnethy after standing half an hour. 



A. On Carnethy. 



At l" 10"> p. M. S = 421 fathoms, / = 32°.4 



1 20 ... S = 422 ... < = 32 .0 



IMeans, 1 15 421.5 32.2 



A. Near Edinburgh, 290 Feel above the Sea. 



At S*- 30™ A. ii. S' = 164 fathoms, i' = 44'.4 



Hence, ... S =421.5 i = 32°.2 



S' = 164.0 <'=44.4 



S — S' = 257,5 t+t' = 16 .6, and m = 1.015 



Whence, 257.5x1.015X6= 1568 feet. 



Correction for height of S' above the sea, . . . + 290 



True height by A, 1858 feet. 



It was thought advisable to try whether, by exposing one of 

 the instruments, while the other was protected as much as con- 

 veniently could be, any very decided difference in the altitude 

 would be found, the temperature being the same nearly, and 

 the sun partially covered with clouds. The instrument denoted 

 by B was placed in a tolerably well protected position, along 

 with A, for the first set of observations on the summit of 

 Carnethy, when the same difference nearly was observed. That 

 denoted by B was then suspended on the top of a small cairn 

 on the other, exposed to a pretty strong north wind, and both 

 instruments were then read a second time without any relative 

 variation. 



True height of Carnethy by B, 1856 



These differ 20 or 30 feet from the former, which is re- 

 garded as correct, because cotemporaneous observations were then 



1 



