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quantity and the latter one which has
already been figured within a few moments
after the opposing craft has been
sighted. It is the duty of the man at
the range-finder to calculate from these
data and the observations of his extremely
accurate instrument the precise
range and to make corrections at intervals
of at least half a minute thereafter.
This information, coupled with
that of the spotter, enables the men in
charge of the "master sight"—an English
innovation attributed to Sir Percy
Scott, wdiich has now been adopted by
every first-class naval power in the world
—instantly to manipulate the delicate
mechanism which raises, lowers and deflects
every one of the big guns. The
introduction of the master sight has enabled
a single corps of trained men to
direct the entire broadside of a dreadnaught
upon a particular point, thus approaching
a greater degree of efficiency
than would be possible under the old
regime where each gun pointer was responsible
for the direction of each gun.
The delicate mechanism of this invention
causes all the 14-inchers instantly to
respond and insures a maximum of effi­
GETTING THE RANGE 379
ciency, provided the data received from
the rangefinder and the spotter are absolute!)'
accurate, a condition which can
THE DELAWARE AND THE ARKANSAS FIRING SIMULTANEOUS BROADSIDES
only be approached by long and constant
practice.
Owing to the "percentage of dispersal"
of each of these guns—estimated at about
400 yards for each gun or 600 yards for
an entire salvo—a broadside from eight
or twelve of these 14-inchers has an
effect analogous to that of a load from
a shotgun. The several projectiles cover
a considerable area of fire and, theoretically
at least, more than fifty per cent
of the shells take effect.
The "percentage of dispersal" is due
to the fact that it is mechanically impossible
at the present time to make every
gun perform equally well with every discharge,
minute differences in the powder
and in the handling of the gun, not to
mention the changes in rifling wdiich follow
every shot, producing varying conditions
of fire which result in an average
difference of 200 yards over or below the
target. But, while this would tend to
militate against the efficiency of a single
gun. the firing of a salvo with every gun
trained at precisely the same point makes