1887.] MICROSCOPICAL JOURNAL. 73 
“fection of the curvature being shown by the symmetrical formation of New- 
ton’s rings when the surfaces were pressed in contact. It was an interesting 
fact that these methods of precision were in constant use in the shops, thus 
securing admirable training for the difficult work. Mr. Mayall witnessed 
the whole process of manufacture of a front lens for an apochromatic one- 
eighth homogeneous immersion, from the grinding to the complete mount- 
ing in its cell, centering, etc. 
Mounting opaque objects. 
Mr. J. Frank Brown (86 State street, Boston) sends us a very neat and 
convenient device for mounting opaque objects which, though not entirely 
novel, deserves mention. It consists in the use of 3x1 inch strips of heavy. 
cardboard, with a hole punched through the centre of 3 inch in diameter. 
The object to be mounted is placed over the hole of one strip, and then a 
second strip is placed over the first and secured to it, thus firmly holding 
the object between them. Mr. Brown, in his letter, says:—‘I send you 
enclosed, a microscopic slide of bolting-cloth or silk, used for straining of 
paint and many other purposes. As it is one of my first attempts at this 
sort of mounting, it is not quite as neat as I hope that practice will enable 
me to do. I send it as a sample of quick and inexpensive mounting for 
many common objects, which are instructive and handsome when seen on 
both sides. This slide is a fine opaque one, and shows finely why the cloth 
is so strong and hard to tear. I had wanted a method of mounting leaves of 
Deutzia, and like leaves, with stellate hairs on its two sides, and finding that 
wooden slides (2 cents apiece) could not be found in Boston, or perhaps short 
of Philadelphia, had this idea of paper slides enter my head, and my stationer 
did the work for me. I pay eighty cents for five hundred of these slips, and 
have them in various colors—green, salmon, yellow, &c. Should my slide 
grow dirty from handling, or its edges rough up, itis easy to make another.’ Mr. 
Brown sends, also, slide of Deutzéa gracilis leaf and Solanum mammosum 
from Florida. Objects which it is desired to view upon both sides, as opaque 
objects, and without careful histological treatment, are in this manner very 
conveniently and cheaply mounted. The method is, of course, not appli- 
cable to a careful morphological examination of the hairs as modified epider- 
mal structures, but such a slide could not be prepared as an opaque object. 
For pleasing and popular objects, and also for many educational objects, as, for 
example, a variety of textile fabrics, which could remain uncovered without 
serious detriment, and which are to be examined upon both sides, this method 
could be followed with economy and real utility. 
New method of fixing sections to the slide. 
By H. E. SUMMERS, 
CORNELL UNIVERSITY. 
The following method has been tested with paraffine and celloidin sections. 
For either kind of sections the slides are first coated with collodion, either by 
flowing from a bottle or by a brush, and allowed to dry. The celloidin used 
for embedding, thinned with alcohol and ether, answers admirably. The 
coated slides may be kept indefinitely before using. 
Paraffine sections are arranged upon the slide and a small amount of a mix- 
ture of equal parts of alcohol and ether is then dropped upon the slide. The 
