The Stourbridge Observer, Cradley Heath, Halesowen & District Chronicle.
Stourbridge, West Midlands, England, 1886-01-23 00:00:00

THE TRANSMISSION OF DRAWINGS
BY SIGNAL,

A meeting of the Royal United Service Institution
was held on Friday in Whitehall-yard, London, Col.
Moncrieff presiding. Among those present were
General Lord Chelmsford, General Sim, General
Eveine, General Lowry, General Manselly, General
Walker, and General Sir B. Walker. Mr. A. Glen
(Lieutenant 14th Middlesex R.V,) read a paper on
"The Transmission of Drawings by Signal," in which
.—a
elaborated in conjunction with Mr. Willink and the
assistance of the signallers of his corps, the Inns
of Court Volunteers. The object of the system, he
said in commencing, was that on person who had
the means of communicating with another by tele-
graph, heliograph, lamp, flag, or other mode of sig-
nalling, might enable the recipient of the signals to
make a fac-simile of any drawing which might be in
the hands of the sender. The drawing might be
of any kind, from a rough sketch or plan to a photo-
graphic likeness or a chromo.lithograph. The accu-
racy with which the drawing was transmitted might
be increased to any extent that the sender might
think fit; while the scale on which the fac-simile was
drawn was at the discretion of the recipient. Having
referred to a scheme invented by Lieutenant-Colonel
Melville, R.E., for transmitting drawings or marks
on a drawing by signal, Mr. Glen proceeded to de-
scribe the details of his invention. The drawing was
divided by actual or imaginary lines into columns of
a certain breadth, and into rows of the same breadth,
at right angles to the columns. If the drawing were
square, and divided into 24 columns, and if the same
number of rows and the columns marked with the
letters of the alphabet (omitting seven and three)
from left to right, and the rows to be marked in the
same manner from top to bottom, any point on the
drawing might then be denoted with a degree of accu-
racy depending on the breadth of the columns and rows
by a group or pair of letters—i.e., the letters marked on
the column in which it appeared, followed by the
letter marked on the row. A straight line joir ing
two points was denoted by joining in one group the
two pairs of letters which denoted those points. A
line passing through a series of points was denoted
by a series of groups which denoted those points, and
in order to distinguish the line from a number of de-
tached points the letter "T "was used. It was im-
portant to save letters and shorten the message when
possible, and if the line eventually reached the point
from which it started, so as to enclose a space, the
pair of letters denoting that point might be omitted
from the last group of the series, leaving the letter
T 'standing alone. A curved line was denoted by
indicating as many points in it as the degree of
accuracy required might demand. The accuracy of a
drawing reproduced from the signalled messages, as
compared with the original, depended on the breadth
of the columns and rows. For a rough sketch, or for
the less clearly defined features of a map, the breadth
might be tin. Generally -gin. would give sufficient
accuracy, but if great accuracy was required, the
breadth should not exceed 1-16 in., while for pho-
tographs he had used columns and rows of
1-32ia. in breadth. Accuracy was no doubt the most
essential requirement in a system of signalling draw-
ings. Brevity was the next, and in order to obviate
the necessity for inserting explanatory or descriptive
sentences in the message, some further rules had been
made, which the lecturer then enumerated. In regard
to apparatus none was absolutely necessary beyond
pap- r and pencil, and such as might readily be made out
of paper; but they had devised several instruments for
their own convenience. Their difficulty had been not
only to construct a message which should accurately
represent a drawing, but to enable the receiver of the
message to ascertain quickly the exact places where
errors, which were no doubt to some extent inevitable,
had crept in, in order that he might at once call for
corrections, and if necessary for the verifisation of the
message, where he found that something was wrong,
without causing unnecessary repetition and delay.
The system, as he had described it, was capable of
transmitting a map or sketch in a comparatively short
space of time, with as much accuracy as be took to
be necessary for military purposes if a reasonable
amount of care be taken in making the message,
signalling it, and working in the drawing. Several
experiments had been made with consideraWe success.
On one occasion, Apr:l 18 last, they took the plan of
the battle of Hasheen and signalled it by flag across
Wimbledon-common, and the copy which was repro-
duced by recipients of the message seemed as useful
for all practical purposes as the original. A photo-
graph had also been reproduced by signal with re-
markable success. Col. Melville, in opening the dis-
cussion, explained the details of his invention, which
related to a method and apparatus for producing,
according to signal, copies of plans or other works,
the like method and apparatus being also applicable
for communicating by cypher, and for which purpose
he provided at each of the two stations which had to
communicate, a board or frame, which was graduated
along the side by distinctive numbers or letters, and
which had fitted to it a graduated rule which could be
slid guided parallel to itself along the board or frame.
Mr. H. L. Pilkington (12th Hussars) raid that he had
no doubt that such a system as Mr. Glen had enun-
ciated would prove of inestimable value in the field,
and that it would become possible for very fairly
accurate sketches to be made in such a manner as he
had indicated. Mr. Glen having briefly replied, the
meeting separated after a vote of thanks to the
lecturer,

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