278 Miscellaneous Intelligence. 
lacks an ake which the others have, by which the relative posi- 
tion of the lenses can be changed, so as to compensate for the thick- 
ness of the in which covers the object, and which appears favorable 
to the examination of those delicate tests. For the examination of 
globules we could not perceive any appreciable difference between the 
‘lenses. 
I would here remark in justice to M. Nachez that he deserves much | 
praise for the manner in which he has improved the microscope in 
France, without augmenting the cost of the instrument, and out of 
England he is undoubtedly the best maker in Europe. ‘To. furnish an 
idea of what he has done to diminish the cost of a good instrument, I 
will compare st price of the objectives which have been the subject 
of the experiments. 
oe ae : : ; e . 9306 francs. 
Spencer, . : ; : ; | ian 
Nachez, . oo So = 
and what is still more he is consul improving his lenses without 
adding to their expen 
The lower powers o Cares makers were éxatined: without finding 
any sensible difference in the defining effects of them, and what little 
there was, was in favor of Spencer. The field of the "res differed, 
Nachez’s being the least, and Spencer’s the greatest. We cannot be- 
is to be regretted that he has not chosen a better mounting for them, 
than, that of Chevalier, which is very defective and prevents good 
glasses from showing their best effe 
I had intended making som sil on oblique light, which has 
mark that much caution is sare in using it, as it will not ANTS 
give correct distances between line 
Logeman’s Magnets.—As he magnets of W. M. Logeman are. 
pele for their power, we insert here a list of his paces Lhes3 
ceived from him in a letter dated Jee cca Sept. o 1850.-- 
A list of the prices of my magnets was published some months ago ~ 
by Prof. Poggendorff at Berlin i in his Annalen der Physik und Chemie. 
ws: 
They are as follow 
No. Force of attraction Price No. Force of attraction Price 
in Prussian pounds. in florins. in Prussian pounds. in florins. 
iF 25 10 5. 1 
2 40 17 6. 200 128 
80 42 te 300 170 
2 7 8. 400 240 
“A. iiss pound is equal to 1-031 English pounds, and two Dutch 
rins are equivalent to one dollar. Straight bars of every size for’ 
magnetical observations, of the same relative ve as the above horse 
