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 2 155. 6d., of which I have formed a very high 

 opinion after having examined a considerable number. 

 The same firm also produces a microscope fitted with 



FIG. 4. Portable Microscope. 



all requisites for bacteriological work for about n 9 

 and this I believe to be quite efficient. 



The cost of the other lenses may be put down at 305. 

 or less apiece. Leitz's No. 3 (about f in.) costs 155., 

 and his No. 6 (about J in.) costs 305. ; 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 



