58 
Warington^ on Additions to his Microscope. 
have done) to use the " Gairdner^' on a cold day in winter 
time. The Coddington herewith employed^ of five eighths of 
an inch focal length (although readily removeable for the 
purpose of substituting one of shorter focus if required), 
suffices to detect all the common forms of the Diatomacese, 
such as Pleurosigma angulata, P. fasciola, Navicula hippo- 
campus, — the smaller forms of Stauroneis_, and even the 
more minute frustules of Bacillaria. 
If the simplicity and utility of the instrument (which it 
has been suggested might be called the " Diatom-detector/' 
from its most probable employment^) be acknowledged, it will 
be unnecessary to occupy the time of the Society by point- 
ing out its usefulness in aiding the collectors of the Des- 
midiacese or of the infinite varieties of Infusorial life, in re- 
jecting what is comparatively worthless, and carrying home 
for further inquiry only the more promising samples of the 
water examined. 
A Description of some useful Additions to his Portable 
Microscope, and Modifications in the mode of using 
the same. By Robert Warington, Esq. 
(Read January 26th, 1859.) 
It will probably be in the memory of many of the 
members, that at the meeting of the Microscopical Society 
in May, 1856, I described a small portable instrument, 
originally constructed for the aquarium, capable of being 
manufactured at a small expense, and being well adapted for 
a variety of purposes, particularly as a dissecting microscope, 
or for sea-side uses and rough investigations. Since the 
reading of that communication I have had the instrument 
packed in the small leather case, now exhibited, as a means 
of conveyance, and so arranged as not to increase the bulk, 
beyond the limits that were actually needed, and at the same 
time in such a way that every part should be exposed to the 
eye and the hand of the operator, so as to be readily taken 
out and as readily returned to its allotted place. 
Since that period also I have had occasion, in the course 
of various investigations, to apply this little instrument in 
other ways than those which were then described, the details 
of which I wish now to lay before the members of the 
Society, as affording facilities for research and observation 
on living organisms, under circumstances the best fitted for 
