429 
of Edinburgh^ Session 1864-65. 
towards some point of the quadrant between north-east and south- 
east. In one case the movement had been from the north-east ; 
but this had soon receded or disappeared, apparently absorbed by a 
new storm from the south-west. 
The observations on temperature indicated that before a storm 
from south-westward reached a place, the temperature rose, and after 
it had passed, the temperature fell at that place. 
The direction of the wind in the storm was ascertained to be 
pretty nearly coincident with tangents to the isobarometric curves, 
though with a tendency to turn inwards towards the centre. The 
author considered that he had established that all storms marked 
by a low barometer, and moving north-easterly, rotated from right 
to left, looking northwards. 
With regard to the violence of the winds, he found that it was 
greatest where the isobarometric curves (having each a difference 
of two-tenths of an inch) were closest to each other ; — when these 
lines, whether of high or of low pressure, were far apart, the wind 
was moderate. 
4. On the Use of Graphic Eepresentations of Chemical 
Formula. By Dr A. Crum Brown. 
The idea of atomicity, or the definite equivalence of chemical 
atoms, is the necessary consequence of the theory of replacement. 
It was employed by Frankland to explain the nature of the organo- 
metallic bodies, and. its application was further extended by Kolbe 
to a large number of organic substances. 
It is, however, to -Kekule that we owe the complete generalisation 
of this idea and its systematic application to all classes of com- 
pounds. This first rendered it possible .to represent, as it is often 
advantageous to do, the constitution of compounds by completely 
dissected formulee. The most convenient way of doing this is to 
employ some suitable system of graphic notation. 
Kekule himself, in his “ Lehrhuch,” made use of a system 
which has the advantage of compactness and clearness, but is 
limited in its application to those compounds in which the poly- 
atomic atoms form a single chain. In order to obviate this incon- 
venience, I proposed, in my thesis presented to the Medical Faculty 
