428 Dr. Moll’s account oj the experiments on 
finger, the index is reduced to rest in the identical moment. 
Thus the index being at o, the spring is pressed down by the 
observer at the very instant the light of the opposite station 
is observed ; the index continues moving till the report of the 
shot is heard, when the finger is withdrawn, and the index 
stopped instantaneously. The number of turns and fractions 
of a turn of the index shows the time elapsed between the 
fire and the report. There was a conical or centrifugal clock 
on each station ; besides these, each station was furnished 
with a good barometer, carefully compared with a stan- 
dard barometer of Mr. Dollond, several good thermometers 
made by Messrs. Dollond and Newman, besides a sufficient 
number of excellent telescopes of Dollond’s, and so placed 
on stands adapted for the object as to bring the opposite 
station without trouble in the field of the telescope. The 
moisture of the air was determined for the first time in such 
experiments by Mr. Daniell’s hygrometer, one of which 
was placed at each station. The direction of the wind was 
determined by very good vanes contrived by the Artillery 
officers. At each station a twelve pounder and a six pounder 
was planted, and the instruments were disposed in, or in the 
vicinity of tents erected for the purpose. Professor Moll, 
with Lieutenants Renault and Dilg, was stationed at the 
Kooltjesberg. Dr. Van Beek, with Lieutenants Sommerton, 
Van Den Bylaardt and Seelig were on the other station, 
which is commonly called Zevenboompjes , or seven trees, from 
the circumstance of seven trees being planted on this lonely 
elevation. Several gentlemen cadets of the Artillery, and 
several students of the University, were at both stations em- 
ployed in observing the different instruments. 
The barometers and thermometers were of course ob- 
