THE SOLAR MICROSCOPE. 
position in the heavens from minute to minute, the position of the 
reflector, which at one time would throw the light in the proper 
direction, would cease to do so after the lapse of a short interval. 
A proper provision must be made, therefore, by which the position 
of the reflector maybe changed from time to time with the motion 
of the sun in the firmament, so that it shall always reflect the 
light in a proper direction. 
10. A perspective view of the solar microscope, mounted in the 
most efficient manner, is given in fig. 2 ; but the principle of its 
performance will be more easily understood by reference to the 
sectional diagram in fig. 3, where c c is the condensing lens, H ii 
the mirror which receives the sun’s light, and reflects it in the 
direction of the axis of the tube. This mirror turns on a hinge, 
by which it may be inclined at any desired angle to the axis of 
the tube ; and a provision is also made by which it can be turned 
round the axis, so that its plane may be presented in any desired 
direction to the sun: a smaller condensing lens is interposed, upon 
which the rays, converging from c c, are received, and by which, 
with increased convergence, they are projected upon the opening 
o o in the slider s s, in which the object is mounted. 
The tube in which the slider s s is inserted, and which carries 
the smaller condenser, slides within another tube, in the end of 
which the greater condenser c c is set. By this arrangement, 
the section of the cone of light, which falls upon the opening o o, 
may be varied, according to the magnitude of the object. 
The amplifying lens, or lenses, L L, are conveniently mounted 
in a tube, which can be moved within certain limits to or from the 
object, so as to accommodate the focus to the position of the 
screen 11, upon which the image is projected. 
After these explanations, the reader will have no difficulty in 
comprehending the instrument, as shown in perspective in fig. 2. 
A board, A A B B, is pierced by a large circular aperture, the 
diameter of which is a little greater than that of the larger con¬ 
densing lens; a square brass plate, a a b b, to which the micro¬ 
scope is attached, is screwed upon this board in such a position, 
that the condensing lens shall be concentric with the hole in it, 
and, consequently, that the axis of the instrument shall be at right 
angles to the board. 
The plane mirror M, by which the light of the sun is reflected 
along the axis of the instrument, is mounted outside the board 
A abb, moving on a hinge, as already described; and screws are 
provided at c c', by means of which its inclination to the axis of 
the microscope can be varied at pleasure, and also by which it can 
be turned round the axis, the screw which governs its motion 
moving on the circular opening s n. By these means, whatever 
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