...Railway artillery - Personal Page of GENE SLOVER

SECl'ION 6.
PREPARATION OF FIRING DATA AND SCHEME OF FIRE
CONTROL FOR LAND WARFARE.
574. This discussion of the preparation of firing data and the scheme
of fire control must necessarily be brief, and hence incomplete. No
attempt will be made to give more than a general outline of the procedure.
The theoretical points connected with the different methods
of laying the piece will be considered first. Next the procedure in
the case of a sliding mount firing from a curved epi will be describedin
detaill and, finally, a discussion will be given of the various corrections
made to firing data and the methods of determining them.
575. LATING THE PlEcE.-Laying the piece includes the operations
of giving the gun the required elevation and direction. Laying
in elevation is accomplished through the use of a vertical measuring
instrument, such as 'the range quadrant, elevation quadrant,
(pI. 464), or gunner's quadrant (pI. 465). Laying in direction is
accomplished through the lIse of a goniometer (French) (pI. 466), or
a panoramic sight (American) (pIs. 467 and 468), in connection with
an aiming or reference point.
LAYING FOR DIRECTION.
576. Laying for direction is accomplished through the use of a
few instruments of which there is a wide valjety of designs, and on one
of two principles differing radically in their ba!3ic conception. Under
the one principle the laying diagram assumes the reference point at
a finite distance from the sighting instrument, and under the other
it is assumed at an infinite distance. In either case the sighting
instrument is set at a calculated or measured angle (usually calculated),
which is one of the two supplementary angles between two
vertical planes, one of which passes through the axis of the gun and
the other through the line from the gun to the reference point, and
the gun is moved until the vertical cross line of the instrument is
laid on the reference point. Obviously, then, when the sighting
instrument is laid on the reference point the gun is pointing in thedirection
of the target. To determine the deflection angle, it is
necessary to know the gisement of the line from the theoretical position
of the gun to the finite or infinite reference point and to be able
,(635)
Digitized by Coogle