502 
MINUTES OF PROCEEDINGS OF 
A DESCRIPTION 
OF 
THE “SCALE OF SHADE,” 
FOR REPRESENTING GROUND IN RELIEF, NOW IN USE AT THE STAFF 
COLLEGE, R.M. ACADEMY, AND SANDHURST COLLEGE. 
BY 
CAPTAIN G. A. CRAWFORD, R.A. 
INSTRUCTOR IN' SURVEYING, R.M. ACADEMY. 
In representing the inclinations of ground by shade, supposing the light 
to fall in vertical rays, a plane surface of a given area—say a piece of paper 
a foot square—would receive the greatest possible number of rays on its 
surface when held truly horizontal; and the nearer the paper is inclined to 
the vertical plane, the fewer will be the number of rays falling upon it. 
On this principle, topographers have adopted the plan of depicting the 
greatest inclination by the darkest shade, reducing the amount of shade as 
the incline approaches the horizontal, which is represented by “ high light.” 
Major Lehman, of the Saxon army, some years ago, endeavoured to reduce 
this system to a certain amount of mathematical accuracy, by assigning to 
different shades definite values in degrees, and so obtaining what has been 
termed a “ scale of shade.” Attempts have been made to introduce a scale 
of shade into this country, but without any result until, within the last two 
or three years, Lieut.-Colonel Scott, R.E., suggested the use of such a scale 
as likely to produce a certain amount of uniformity in the work of different 
draughtsmen, and Captain Webber, R.E., and others, wrote pamphlets upon 
the subject. At one of the meetings held in London by the Royal Engineer 
Officers, to which the instructors in surveying and topography at the 
different military colleges were invited, the matter was fully discussed, and 
the scale of shade I am now about to describe decided upon by the Council 
of Military Education/and its use authorised by H.R.H. the Commander- 
in-Chief. 
It will be observed that 35° is the steepest inclination represented by 
shade upon the scale. Slopes of 45° can be shewn by as dark a shade as the 
draughtsman's pen will permit of; inclines above 45° are supposed to be 
