ADJUNCTS OP DEFENCE. 
461 
out ? (1.) It reduces {a) to tlie comparatively simple operation of 
laying the cross-hairs of an easily manipulated telescope on a mark. 
By this one operation the range and the line of bearing are automatic¬ 
ally transmitted to the emplacement, there to be translated from dials 
to pointers connected with the mounting. Thus, conditions (a) and (£) 
are both fulfilled, while corrections (c) and (d) remain to be applied, 
either by the operator or in the emplacement. (2.) Since the instru¬ 
ment enables the course of a vessel to be followed and plotted, the 
prediction involved in the supplementary correction can be made without 
difficulty unless the course of the target is specially erratic. (3.) The 
position of the observer being independent of that of the gun, the 
latter is able to carry on aimed fire over water not visible from its site. 
(4.) The operator is removed from danger, and is comparatively little 
liable to have his field of view obscured by smoke. 
The instrument, when in adjustment, is theoretically perfect, and 
from its nature the probability of observation error is reduced to a 
minimum. 1 Assuming adjustment and electrical communication to be 
maintained, it is also practically perfect. Thus, once the principles are 
fully grasped, first thoughts naturally lead one to assume that an 
absolute solution of a difficult problem has been reached, and that a 
new method so accurate and simple as to demand general application 
has been provided. 
Further consideration serves to modify this view materially. Assume, 
for example, that condition ( b ) can be otherwise fulfilled, or that accurate 
ranges can be otherwise obtained. Then clearly a portion of the advan¬ 
tages of the system disappear. To lay for line by sight is an easy 
operation, and two possible sources of error—the mis-reading of a 
dial, and the incorrect adjustment of a pointer to an arc are actually 
eliminated. The possible sources of error in elevation remain practic¬ 
ally unaffected. Although prediction, in the sense above adopted, may 
not be equally inconvenient, the difference will not be marked. The 
instrument does not remove the more important sources of error, 
which still depend upon fallible private judgment. Thus, on purely 
theoretical grounds, it might be expected that when good range-finding 
can be carried out, no increased accuracy of practice can be attained 
by position-finding. Practical experience appears to bear out theory 
in this respect, and now that a good system of drill exists there is 
reason to believe that superiority both in speed and accuracy of fire 
can be claimed for the range-finder. 
Abandoning theory and coming down to matters of infinitely greater 
importance in war—tactics and human nature—certain inevitable dis¬ 
advantages attach to the new system. Under it the responsibility for 
accurate practice centres upon the observer in his cell. The gifted 
individuals to whom the grave responsibility of directing the fire of a 
heavy gun or group of guns may safely be entrusted, become the real 
commanders of the battery in regard to its war functions. They 
must be trained officers, possessed of iron nerve and wide experience. 
But, if this is admitted, a necessary limitation at once presents itself. 
1 This applies to a vertical base instrument only. In the case of a horizontal base apparatus 
other sources of error arise. 
