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according to the given co-ordinates. This allows one man to operate the co-ordinatograph
without leaving the drive unit.
The instrument consists of a massive table, drive unit, carriages x and y; registers
and the electrical device (Fig. la and b). The transmission unit includes two flywheels
ji and n, which set the screws of the instrument in motion through gears assembled in
the gearbox; the screw moving carriage y, a Square bar transmitting the motion to the
screw of carriage x, a cylindrical guide along which moves carriage x, and the front
and rear brackets supporting all the mechanisms of the drive unit.
The screws of carriages x and y, through the gearbox gears, rotate the registers whose
readings indicate the values of the carriage movement.
The left meter C, indicates the travel of carriage y, the right C2, of carriage x.
Here are some specifications of the co-ordinatograph
error in setting points, not more than ±0.1 mm;
register-reading accuracy 0.05 mm.
The second stage, the transfer of the model from the cartographic material to tne
original offers no difficulties in the compilation of topographic maps. This is done by
simple copying with a simultaneous reduction of the size of the copies.
Transformations
In the compilation of many small-scale geographical and special maps the task is
complicated by dissimilar projections. Very often a copy has to be imposed on an ori
ginal differing substantially from the projection of the cartographic material. This has
produced a variety of technical methods in the compilation of maps. All of them are
subiect to the laws of point transformation.
The formulas used in transforming cartographic data are somewhat different trom
the functional relations described above. The initial formulas for transferring the model
from the cartographic material to the original are derived by substituting rectangular co-
ordinates for the geographical co-ordinates in the functions fx, f2
X F1 (x,y) Y F2 (x,y) (2)
Formulas (2) make evident that they are point transformation of figures, in parti-
cular of one cartographic projection into another, where X and Y are rectangular co-
ordinates of the map original, and x and y, the co-ordinates of the cartographic original
According to Prof. N. A. Urmaev's general theory, the right sides of the formulas (2)
may be regarded as the first terms of polynomes derived from the series development
of functions F,, F2the origins of the co-ordinates correspond; the co-efficients are
proportional to the particular derivatives of function Fx and F2. The simplest transfor-
mations can then be singled out: transformation of similarity, affine transformation.
and transformation of the second order and sometimes higher.
Electronic photo transformer
Transformation of the second order and higher underlies the latest electronic methods
of transferring the model from the cartographic material to the original. Electronic
transformation, described below, is noteworthy.
The electronic cartographic transformer designed by M. P. Bordyukov (Fig. 2),
consists of a transmitter (iconoscope 7) and a receiver (kinescope 3) cathode-ray tubes,
power pack 6, amplifier 5 and reducer 4.
The rays of picture 9 of the cartographic material pass through lens 8 and are con-
verted in the iconoscope into electric signals which are transmitted to the kinescope.
There they once again become a visible but already transformed picture of the carto
graphic material which is projected through lens 2 onto original I being compiled.
