BACTERIOLOGICAL MICROSCOPE. 5 
work at a distance, for it packs into a very small 
compass and is not heavy. 
The cost of a in. oil immersion lens is, roughly 
speaking, £5. Beck supplies a good lens for £4, and 
Messrs. Gowlland of Selsey, Sussex, are now making 
one for £2 15s. 64., of which I have formed a very high 
opinion after having examined a considerable number. 
The same firm also produces a microscope fitted with 
Fic. 4.—Portable Microscope. 
all requisites for bacteriological work for about £11, 
and this I believe to be quite efficient. 
The cost of the other lenses may be put down at 30s. 
or less apiece. Leitz’s No. 3 (about 3 in.) costs 15s., 
and his No. 6 (about 4 in.) costs 30s.; these are both 
extremely well adapted for bacteriological work. 
With regard to eye-pieces, it is an advantage to 
have two,a No. 2 and a No. 4. Higher powers may 
be used, but it must be remembered that any increased 
