588 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
be seen when a blue glass was interposed. With the other, lines could 
be seen under ordinary conditions, but they disappeared when a yellow 
glass was interposed or when petroleum light was used instead of day- 
light. With light which had passed through a flint glass prism, the 
objectives resolved in the blue but not in any other part of the spectrum. 
In the blue of the spectrum the author could resolve with a 1/5 what 
could only be resolved by a 1/15 in ordinary light. 
As the result of experiments carried on for several ye'rs up to the 
present time, the author makes use of a slide of mica coloured blue with 
anilin blue which he places in the path of the illuminating beam of 
light for the Microscope. 
(4) Photomicrography. 
Tylar’s Photomicrographic Camera..* — The author of this little 
pamphlet of eight pages gives detailed instructions for beginners in the- 
use of the photomicrographic camera which he has devised. The appa- 
ratus (fig. 94) may be described as an elementary low-power plioto- 
Fig. 94. 
micrographic camera. According to the author’s instructions it is 
intended to be used with the Microscope from which the eye-piece ha& 
been removed ! It is also essential that the whole apparatus should be 
firmly clamped to the table, and this would almost necessitate the use of 
the photomicrographic board. This point, however, is not mentioned 
by the author, so that “ the initial outlay of 27s. Gd.” does not include 
an essential part. 
The table of exposures for different objectives given by the author i& 
of little use, since the magnification is not stated, and the limits from 
3 to 45 seconds are too wide ; but the advice which follows is so good 
that it may be quoted at full : — 
“ I personally advise the waste of the first plate in obtaining an 
approximate guide for the exposure of the rest of the plates, and proceed 
* W. Tylar, ‘ The Art of Photographing Microscopic Objects,’ Birmingham, sm. 
8vo (n.d.). 
