40 
MINUTES OF PKOCEEDINGrS OE 
REMARKS ON 
CAPTAIN NOLAN’S BANGE-HNDINI} APPARATUS. 
BY 
LIEUT. C. E. B. LEACOCK, R.A. 
Captain Nolan's range-finding apparatus consists of two angle-finders, 
a measuring tape, and a calculating roller. 
The angle-finders are identical in general construction, but inverted in 
details, one instrument being right, and the other left-handed. 
Each angle-finder consists of a long telescope, round each end of which 
is a band, turned truly round. The bands rest on two Y's fixed on 
the outer side of the barrel of the gun, so that when the telescope 
is laid in them, the axis of the telescope is parallel to that of the gun; 
above the telescope is an index plate, graduated in a manner which will be 
hereafter described; at the rear of the index plate is a pivot, on which a 
steel limb revolves. Above the steel limb at the pivot, is fixed a short 
telescope, which revolves with the limb, and remains constantly at right 
angles to it. The limb and short telescope receive their motion from a 
screw fixed to the index plate, and working through a nut on the steel limb. 
The short telescope is protected by means of a tin case, to the inner lip of 
which is pasted a white paper ring. This case does not revolve, but is 
fixed at right angles to the index plate, a hole being cut in its side so as 
not to interfere with the index bar. 
The tape is an ordinary measuring tape, working on a reel. At the loose 
end is a hook, which, when the tape is used, is hooked to the inner trail- 
handle of one gun, and the reel is then carried over to the trail of the 
other. 
To measure the range by means of the instrument, two guns are used. 
They are drawn up at an interval of about 40 yds., and dressed so that the 
object will be directly in front of some point in the interval. Each gun is 
then laid on the object, and the interval from inner trail-handle to inner 
trail-handle measured. The short telescope of each finder is then turned on 
the vertical axis of the white ring on the lip of the case of the other. This 
axis is marked by a red spot on the highest and lowest points of the circum¬ 
ference of the ring. The angles between the long and short telescopes will 
consequently be the base angles of the triangle ABC, formed by the object 
and the two guns, and their sum will be the supplement of the angle BAC. 
(See Diagram I.) 
