Scientific Intelligence — Meteorology and Geology. 421 



The three points being approximately, 8, 54, and 143 feet 

 above the bed or floor of the glacier. 



These results liave been computed by the following for- 

 mulae, which may be useful to those desirous of repeating the 

 observations : — 



Let X and x be the two trigonometrical stations from 

 which the motion of the points (1.), (2.), (3.), are observed. 

 Let 6 be the angle under which X and z are seen from one of 

 these points. Let p be the linear transversal movement of 

 the point as seen from X (deduced from the apparent angular 

 motion and the known distance of X). Let q be the similar 

 quantity with respect to a*, which will have the same or con- 

 trary sign with p, as the apparent motion from the two sta- 

 tions is in the same or in contrary directions. Then the total 

 motion of the point observed (which is assumed to be small 

 relatively to the dimensions of the triangle, which has X, a:, 

 for two of its corners) will be 



^=\/gr + (g cotan d— f cosec d)^ 



and the angle {<p) of the direction of motion with the visual 

 line through X, is found by this equation 



sin a = -^- 

 ^ r 



I shall take the liberty of addressing you again, as to the 

 fai*ther observations which I have been able to make, in 

 another letter. — I remain, my dear Sir, yours very truly, 



James D. Forbes. 



Larqs, Ayrshire, 16«A September 1846. 



To Professor Jameson. ,1,. , . 



SCIENTIFIC INTELLIGENCE. 



METEOROLOGY AND GEOLOGY. 



1. Sulphur in the Atmosphere. — ^M. Boussingault lately made a 

 communication to the French Academy of Science on the much-dis- 

 puted point of the presence of sulphur in electricity. It is generally 

 stated that an odour of sulphur accompanies the electric fluid. This, 

 however, has been positively denied by many natural philosophers. 



VOL. XLI. NO. LXXXir. — OCTOBER 1846. 2 E 



