iio & Scientific Intelligence. 
not lie in the same plane. This effect is imitated 4 as Dove in two 
printed stereographs—sce Sept. No. this Journal, p 
' [If a printed page be magnified by a plane cofivél fina 3 inches in 
diameter 24 in fucal length, and viewed by both e t will be seen that 
the letters are raised in the centre of the field, so that it putea - ayspear- 
ing flat seems to be convex. A single projection of a pyramid placed 
under the centre of the lens gains relief, though the lines i bee from the 
base to the apex rise toward the observer in curves. ‘The effect is due to 
the distortion A tigi by viewing the drawing through the opposite 
halves of the 
On the oti’ * nd if two perfectly cond printed pages be viewed 
through the lenticular stereoscope, attentive examination will show that 
the field is apparently concave: the bias: rising in shallow tiers, above 
and below; this is of course a defect in the instrument, since it alters 
relief in which the objects are seen, increasing or diminishing it according 
to their position in the field. 
On this account it may perhaps be advisable even where the most natu- 
_ral relief is desired to place the cameras somewhat farther apart than the 
distance between the eyes. Sir David Brewster, in his work on the stere0- 
scope, page 108, gives us to understand that Whieatstone’s reflecting 
stereoscope is not a “real or serge semi ) because pieces of looking 
glass are employed in it. Must we inte strike Sir David’s lenticular 
stereoscope from the catalogue of optical sbbolba atus because semi-lenses 
are employed in it, which alter the mavdeat relief, in which according to 
the same author it is so essential that objects should be viewe 
n interesting article on the apprscation of the Ster eoscope to dis- 
tinguish aloe — fac-simi rilies.—When two valde rinted ee the 
the stereoscope be seen to lie in gee planes—(See the illustration 02 
page 304, vol. XXX, this Journ 
y this means when poriile ‘and counterfeit bank notes are combi ned 
in the stereoscope the difference is at once detected. This is peer a 
method of apparently converting eee in a horizontal, into depth in 
vertical ar and great] magnifyin ng i 
n the Electric Light coats an analysis of the weaker varieties 
of electric light by means of colored glasses. In passing from n 
more like that of the pale flame of oe which | becomes gh ine and 
white by the introduction of solid m 
mprovements in the Microsco i ham’s Improved Biideli 
Microscope.—In the Quarterly Journal of Microscopical Science for acer a 
1860, Mr. Wenham has described an improved form of Binocular Micro- _ 
the 
The construction of this instrument will be understood from 
