1897 THE MICROSCOPE. Et 
it the right size to hold the lens. If it should be a trifle 
too small, the lens may be ground down on a common 
grindstone. If it be too large it may be filled up with a 
second ring of tin, or even cardboard. 
To fasten the lens in its place, various devices may be 
used. We fastened ours with sealing wax, and it answers 
very well. This wasdone by heating the loop until it 
would melt the wax, and then coating the inside of it 
with that material. While the wax was still soft the 
lens was pressed to its place, and the loop was again 
gently heated, so as to cause the wax to adhere to it 
firmly. A more mechanical and artistic method would 
be to get two rings of sheet tin, each an eight of an inch 
wide, and just such a size as would fit into the inside of 
the loop. These two rings are to be soldered to the loop 
the lens being between them. Various other ways may 
be suggested, but the sealing-wax answers very well. 
The next step is to connect the lens and its frame with 
the stand, and this is done by means of the cork. Two 
holes are bored through the cork, as shown in Fig. 2; 
one passes lengthwise through the center, and the other 
hole passes through the cork at right angles to the first 
and a little to one side of the center. These holes can 
be made by means of a cork-borer, which is a small tube 
of sheet tin or brass with the edges sharp; or they can 
be made by first passing an awl through the cork and 
then enlarging the hole to the proper size by passing a 
red-hot wire through it, an old knitting needle answering 
very well. As soon as the holes have been bored, the 
whole may be put together as shown in Fig. 3. and the 
condensing lens 1s complete.—Popular Science. 
Dangers of Barber Soaps.—T he Union Med. du Canada, 
commenting on a recent case of staphylococcus infection 
contracted by a physician in the barber’s chair, asks why 
should there not be a municipal regulation compelling 
barbers to sterilize their instruments. 
