ADJUSTABLE POINTERS. a9 
By turning the pointer round as much as is required any desired 
nicety of correction can be obtained. (It would beas well to cut away 
the edge abc). Now to obtain this nicety a multiplier in the shape 
of a drum and index must be fixed at the top of the bolt which con- 
stitutes the present pointer. 
Fie. 2. 
Front HLEvaArion. Sipe VIEw. 
Wote.—For convenience of reading and to get the graduations on the drum in front, the index 
had best be fixed to one side. 
The index points at D round a narrow drum A BC several inches in 
diameter (so as to get the division sufficiently large for easy reading) 
on which are marked the corrections for various ranges. By making 
the radius of this drum sufficiently large, say about 3 or 4 inches, the 
graduations may be made as fine as to hundreds of yards up to 2500 
yards and every 300 yards above that. 
For No. 4 gun which requires a correction twice as great as No. 3 
the drum must be proportionately of greater radius. The small brass 
pointer of No. 4 gun must also be fixed 1 inch further out. 
The are of the drum must also be larger if the guns are further apart, 
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