136 Account Amlcrs Reflecting Microscope. 
the under part of the body of the tube, it throws it towards the 
concave mirror, in which it may be examined by the eye of the 
observer, applied to the opposite end of the tube, through a 
greater or smaller number of magnifying eye-glasses, which may 
be fitted to it. 
The internal diameter of the tube, which regulates that of 
the large mirror, may be inches, and the thickness of the 
surrounding metal about ^ oth. Upon this construction, the ob- 
ject to be examined may always be at the distance of half an inch 
from the edge of the tube, and consequently be very well light- 
ed on every side, — transparent objects from below, by means of 
a common illuminating mirror, fitted to the pillar, and move- 
able, — and opaque bodies from above, either by the natural 
light falling directly in, or by concentrating an artificial light, 
by means of a convex glass fitted to the object-bearer, — or 
still better, by means of a pierced mirror of metal, which is fit- 
ted to the tube below, over the object, so as to be brought more 
or less near to it. The large illuminating mirror below should 
be concave, having a diameter of three inches, and a focal dis- 
tance of 2.5 at the utmost. 
The effects of the two last-mentioned mirrors may be recipro- 
cally combined, by means of a common corresponding adapta- 
tion, — ^by receiving and reflecting the rays of light, so as to pro- 
duce the highest degree of intensity of light, and the most per^ 
feet illumination of the object on all sides, both as a whole, and 
in its different parts, — an advantage, indeed, which may be at- 
tained in dioptrical instruments, by similar means. 
The inventor considers the proportions above given as best 
^ adapted for the convenient use of the instrument, in order to 
preserve, along with a high degree of effect, and even the high- 
est degree of magnifying power, a moderate distance of the ob- 
ject from the microscope, viz. half an inch, which not only al- 
lows the most simple and perfect illumination from above, but 
also admits of our examining objects of a considerable size en- 
tire, without separating the parts, and also small animals ahve. 
A common dioptrical microscope, whose object-glass has a focal 
distance of six lines, would correspond with this state of the ob- 
ject, and consequently admit of similar advantages,but with a much 
-diminished magnifying power, of about 1500 or 2000 in the area. 
