218 
Accurate Balances. 
[July, 
The method in which an oblique illumination is assumed, called at Sandhurst 
the French method, is totally inapplicable to military plans, there being no possi- 
bility of distinctly expressing the commands on the enlightened side of the ground. 
The only instance in which it is used at the Royal Military College, is in the 
plans of fortifications; and even here, notwithstanding the advantages it has on its 
side, as antiquity, the prejudice of the eye against innovation, and the pleasing 
variety of light and shade falling in alternately, opinions have been frequently 
given agains't it ; and if it have not already given way, it doubtless soon will, to a 
more useful method, in which the degree of shade will represent the command, 
without reference to any other contingency. Another style of topographical 
drawing, deserving pre-eminently the appellation of the pictorial, has been attempt- 
ed. The plan is drawn in the actual colours of the landscape, and the light is 
made to fall in an oblique direction, 45° ; the eye is placed in a plane, having an 
inclination to the horizon of about 20°. A plan of part of the country about the 
lakes of Killarney, and of some mountainous and wooded ground, illustrative of 
some military operations in the West Indies, done upon this principle, and upon a 
very large scale, made a splendid appearance ; but the subjects were purposely 
selected with a view of exhibiting the effect of such a method. It can only e 
used in particular cases, and is not at all suited to general purposes. In the paper 
upon this subject, in the 14th Number of the Gleanings, the attempts of our map- 
makers to represent the inequalities of the surface, are most justly censured, 
nothing can be more absurd than their shadings : valleys are made to look like 
hills, and hills like valleys ; and the unfortunate rivers are as frequently mate to 
meander up the sides of mountains, and along rocky and precipitous ridges, as m 
the plains and glens. It would be in vain to trace their principles from t > ur 
practice ; they appear to darken the map without any rule, other than their on 
caprice: the French map-makers are not much superior ; they however do try 
to adhere to the rules for the oblique illumination. The Germans are certain y 
• 17 M Jj, 
better, but their work is dreadfully coarse. h 
V . — Accurate Balances. 
In the course of the last few yeai*s, the increasing accuracy of scientific rese ^ 
has rendered necessary corresponding improvements in the implements ^ 
In the balance and unit of weight, and in the unit of measure particular ) » 
ments indispensable in almost every operation of a chemical and physica ^ 
the first philosophers of their day have introduced essential improvements 
latter we hope hereafter to give our readers some idea, in describing the nev ^ 
ing bars for the use of the trigonometrical survey : at present we shall con 
attention to the former object. er . 
Captain Kater has described, in the Cabinet Cyclopedia, a number of the 1110 ^ 
feet balances used in England, and his account would have been comple^^^ 
favored us with plates of the most ingenious or delicate of them ; in this de ^ ^ 
however, he is not singular ; for in most works on mechanical philosophy* ^ ^ 
repeated a clumsy figure erroneous in the commonest principles, (plate • » 
which few respectable instrument makers would select for imitation. ffe ]l 
The real principles upon which the delicacy of a balance depends, ETe ^ 
known to need repetition at length : the beam is regarded as an infl eX1 ^ 
turning upon an edge or fulcrum in its centre, and carrying two suppo rts > ^ j g g0 
distances, and in a right line, on either side, (fig. I.) The centre of gra j t j 0 n- 
much below the fulcrum, as to enable the beam to preserve a horizonta 
