56 NOTES AND MEMORANDA. ^^uS! Ja^^^^^^^^^ 
outer ones, whicli at their cutting parts have the middle surfaces 
slightly concave, and the external surfaces obliquely or double-wedge 
shaped. The three blades have two cutting edges, one a trifle more 
curved than the other, the points or tops being cut in a slanting 
direction. Near the centre, the middle blade has a couple of opposite 
fixed eyes, which pass through transverse slots in the outer blades, 
these having each a spring- thumb- slide catch, which can be pushed 
through the projecting eye. The blades are held together by a screw 
and nut at the end of the handle, and when released at the thumb- 
catches, tend to spring outwards, but when the catches are pushed 
through the eyes, the blades are brought into opposition. To open 
the blades the necessary width, a tangent screw, passing through each 
outer blade, acts against the middle one, parallelism being obtained 
by regulating the distance the thumb-slides are pushed through the 
eye-loops, and screvang or unscrewing the two tangent screws. 
Sometimes it may be necessary to very slightly release the screw 
nut at the end of the handle. The advantages I claim for this triple- 
section-knife are these : — 
Two parallel sections of similar or dissimilar thickness can be cut 
from one part, which when spread out will offer a double surface for 
examination and facilitate tracing the parts of contiguous surfaces. 
This in pathological researches may be of moment, as assisting the 
microscopist to find the adjoining points of healthy and diseased 
structures. By the removal of an outer blade it is converted into an 
ordinary double-bladed section-knife. Facility for cleaning the surfaces 
after use, and the little chance of any of the parts being misplaced. 
My first sections with one of these knives were most successful, 
being entirely through the tongue of a newly-born puppy in the 
direction of its length. The blades require to be well wetted with the 
liquid most suited for the specimen, or one which will not injure 
either the knife or the structures. The object may be placed on fine 
cork, parchment, or thick leather, being held steadily between the 
finger and thumb, the sections being made by one saw stroke if 
possible ; or the object may be simply retained between the finger and 
thumb in making the section. It may be said this knife differs but 
little from the ordinary seetion-knife ; such is the case, yet it is this 
little that makes all the difference. 
A "New Lamp for Microscopic Purposes has been devised by 
Thomas Fiddian, Member of the Birmingham Microscopical Society, 
who sends us the following account : — 
The importance of artificial light for the illumination of micro- 
scopic objects has long been admitted by men of science. To profes- 
sional men and amateurs, whose time is fully occupied with other 
pursuits during the day, it is an absolute necessity, and even to those 
who have ample leisure hours of daylight its importance is very great, 
for it cannot be denied that in our climate the quality of natural light 
is very variable. The difiiculty has been to obtain a concentration of 
intense white light upon the object, and at the same time to exclude 
all extraneous light from the object and from the eye of the observer. 
