90 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Microscope. A further improvement is a spring clip, enabling the 
object to be easily changed without scratching the labels, &c., its con- 
struction admitting of either a deep zoophyte trough or the thinnest 
3x1 slip being held gently but firmly. The parts are supplied 
separately, so that auy one needing only the lantern arrangement can 
add the other at any future time. 
(3) Illuminating and other Apparatus. 
The Substage Condenser: its History, Construction, and Manage- 
ment ; and its effect theoretically considered.* — Mr. E. M. Nelson 
remarks — “ The substage condenser is nearly as old as the compound 
Microscope itself. The first microscopical objects were opaque, and in 
very early times a lens was employed to condense light upon them. It 
was an easy step to place the lens below the stage when transparent 
objects were examined. 
Coming to more modern times we find that the culminating type 
of non-achromatic Microscope was fitted with a substage condenser, 
but it had a very brief existence, not being able to hold its own against 
the recently introduced achromatic. Had the invention of achromatism 
been delayed, it would, I have no doubt, have had enormous popularity 
for those times. I allude to the Wollaston doublet with its substage 
condensing lens, particularly that form designed by Mr. Valentine and 
made by Andrew boss in 1831. 
Before proceeding we must remember by whom the Microscope was 
used at that time. As far as this country was concerned, it was merely 
looked upon as a philosophical toy. It was principally to be found in 
the hands of a few dilettanti ; science of every kind was tabooed, the 
Microscope being placed at the lowest end of the scale. 
Now. the Microscope of the dilettanti is usually a perfect instrument 
of its kind, fully supplied with apparatus, the greater part of which is 
absolutely useless, but among this apparatus there would always have 
been a substage condenser. One of the principal things the dilettanti 
have done for ns is the keeping up through early achromatic days of 
the continuity of the condenser. 
On the Continent, where science held a much more important place, 
the real value of the Microscope was better understood, and it at 
once took an important place in the medical schools. But the increase 
of light due to the more perfect concentration of rays by achromatism 
enabled objects to be sufficiently illuminated by the concave mirror to 
meet their purposes. Therefore, we find that on the Continent the 
Microscope had no condenser. Of course there were isolated excep- 
tions, Amici’s for example ; but T think we may safely say that for 
every Hartnack made with a substage condenser there were upwards of 
one thousand made without. 
England followed the Continental lead, and now the “foolish 
philosophical toy ” has entirely displaced in our medical schools the 
dog-Latin text-book with its ordo verborum. But the kind of Microscope 
adopted was not that of the English dilettanti, but the condenserless 
Continental. It may be said that the Microscope for forty years — that 
* Joum. Quek. Micr. Club, iv. (1890) pp. 116-36. For the use of the accompany- 
ing plate we are indebted to the kindness of Mr. Nelson and the Quekett Micro- 
scopical Club. 
