170 
EXPERIMENTS MADE IN RUSSIA 
WITH 
THE “LE BOULENGTf! ” TELEMETER. 
TBANSLATED EEOM THE SPANISH BY 
LIEUT. J. C. DALTON, R.H.A. 
Translator’s Preface. 
The description of tlie following experiments appeared in a Brussels paper, and 
was taken from the “ Invalide Russe.” The instrument used was the telemeter, 
invented by Major Le Boulenge, of the Belgian artillery. 
Before describing the experiments, it would be as well to explain the instrument. 
Its object is to tell ranges by measuring the intensity of the report of a distant, 
piece of ordnance. There are two classes of the instrument, and Major-General 
Yoyle, Retired Royal (Bengal) Artillery, thus describes them in his “ Military 
Dictionary ” 
“ The first is composed of a glass tube, provided with a graduated scale representing 
distances, and containing an index floating in sulphuric ether. The observer, after 
having previously brought the index to the extremity of the tube that corresponds 
with the beginning of the scale,'places the instrument horizontally in his hand, and 
watches the enemy’s position. As soon as he perceives the smoke of a gun, he 
brings the instrument suddenly into a vertical position, and the index descends 
along the tube; then, when the report is heard, lie reverses the telemeter, and the 
index remains stationary. The division of the scale on which the index has stopped 
gives the distance between the gun and the observer. 
£t The second is made on the same principle, of such small dimensions, and of so 
compact a form, that it can be easily fitted in and carried by any small-arm. It is 
composed of a small crystal tube, closed at both ends, and filled with rectified 
benzine. In the tube an ivory index floats, painted red. The instrument is 
encased in the flat part of the stock of a rifle, perpendicular to the axis of the 
barrel. A small opening cut in the wood enables the reading of the scale. The 
mode of using it is very similar to the before-mentioned instrument, the rifle being 
turned instead of the hand.” 
In the description of the experiments it does not mention which of these classes 
of the instrument was used, but the results appear to have been satisfactory; and 
although the accuracy of an instrument such as this (the main principle of which is 
the velocity of sound) must depend greatly on weather, temperature, &c., still from 
these results one must consider the instrument well worthy of notice. 
J. C. D. 
J3ALLINCOLLIG, 
18th Juno, 1877. 
