23 
A New Erecting Camera Lucida. By E. M. Nelson. 
be repeated, viz. that when with a critical image the light becomes 
too strong it should be modified by glass screens placed at the back 
of the substage condenser, and not, as is too often the case, by racking 
the condenser out of focus, which would instantly put an end to the 
criticalness of the image. 
As the inversion and transposition of Microscope images, either 
when projected or photographed, or seen through various cameras, is 
not quite so simple as it appears, and as in works on the Microscope 
and on photomicrography the subject is conspicuous from its absence, 
I have drawn up the following table which will, I trust, place the 
phenomena in the clearest possible light : — 
l. 
Object on stage. 
F 
2 . 
Image seen 
through eye-piece. 
d 
f 3. 
Image projected 
on screen or on 
sensitive plate. 
5. 
Image seen 
through 
Wollaston’s 
camera. 
d 
7. 
Image projected 
on table by 45° 
mirror or right- 
angled prism 
(0. W. Cooke, 
1865). 
F 
4. 
Image seen 
through ground 
glass. 
F 
6 . 
Image seen 
through Beale’s 
neutral tint or 
Soemmering’s 
mirror. 
-=\ 
8 . 
Image seen 
through Nelson’s 
camera. 
n 
No. 2. This is the image that is traced when cameras, which project 
the image of the paper and pencil down the tube of the Microscope, 
are used. No. 1 can be reproduced by inverting the drawing. 
No. 3 is important, because it shows that when a projection 
Microscope is employed, though the image is erect, it is still trans- 
posed. Further, when a negative is printed by contact, or copied 
by projection in a camera, provided that the film faces the lens, the 
print will be the same as the original. (Note, in an ordinary land- 
scape camera, although the case is different, the image on the sensitive 
plate being inverted and not transposed, thus h, yet when printed 
