234 J. Lawrence Smith on the Inverted Microscope. 
through Mr. Nachet’s neglect to mention who the inventor of it 
was while. exhibiting it at the World’s Fair in London last year, 
or through thé forgetfulness of Mr. Quekett, after being informed 
on the subject. This omission is still more glaring, from the fact 
that the instrument as then exhibited, with one or two very un- 
important modifications, is the same in all its mechanical details 
as was constructed for me, from my plans, by Mr. Nachet, of 
Paris, and used in the laboratory of Messrs. Wurtz and Verdiel. 
I am sorry to be obliged to preface the description of the Mi- 
croscope with this reclamation ; but after considerable experience, 
I feel that the instrument is an important one for general as well 
as chemical purposes, and that it will in time be coffsidered a de- 
cided advancement in the construction of microscopes ; with these 
views in the matter, Iam unwilling to yield, what little credit 
might be due to the inventor of it, 
The great development made in microscopic research, during 
the last twenty or thirty years, is due in great part’ to improve- 
ments in the construction of achromatic object-glasses ; still, the 
mechanical arrangements of the instrument have contributed 
their share to facilitate observation, and diminish the fatigue de- 
ndent upon this character of research. In fact, observers have 
not hesitated to make use of different descriptions of mounting 1n 
their varied field of research ; and now, we have instruments for 
general purposes, but the construction of which is imperfectly 
adapted to certain special researches ; as, for instance, the dissec- 
tion of animal tissues. This last circumstance has given rise t0 
the invention of various forms of dissecting microscopes, such as 
the Pancreatic Microscope of Oberhauser, and more recently the 
simple and better instrument for arriving at the same end con- 
structed by Nachet, of Paris. é 
These remarks are made to show how the use of the micro- 
scope might be extended by paying proper attention to its. me- 
chanical arrangements, and it is from this cause I have been led 
to seek out a form of instrument, by means of which micro-chem!- 
cal research might be facilitated and enlarged.. The instrument 
about to be described is calculated to produce these results. 
The great obstacle to chemical research beneath the microscope; 
are two-fold; first, the necessity of manipulating in the limited 
space between the object-glass and the stage; and, secondly, 
exposure of the most essential parts of the instrament to the va- 
pors emanating from the re-agents employed, and the condensa- 
.- ope. 
ted, 
tabove 
it, with an optical arrangement of such a nature as to permit gh 
servation. It was with this in view, that M. Chevalier made 
