120 ` General Notes. [February, 
Mextcan MIGRATIONS. — At the Exposition International de Géo- 
graphie held at Paris last year, Professor Quatrefages exhibited an un- 
published map illustrating the migrations of the Mexicans. 
MICROSCOPY.! 
AMATEUR Microscorrs. — The notorious success of Mr. Wenham, 
the late Mr. John Williams, and some other microscopists, in preparing 
their own apparatus, is exceptional only by reason of the degree of excel- 
lence attained. It is especially true of microscopists that they love the 
instruments they work with, and from this love follows not only the par- 
tially unfortunate “ test-object fever,” but also the eminently useful habit 
of studying, adapting, altering, and finally manufacturing accessories, if 
not instruments, suited to their needs and fancies. Such amateur work 
not only is the best possible drill in the science of the microscope, but 
also has added very largely to the development of the microscope of to-day. 
The European journals are full of interesting and profitable results from 
such work; while the readers of the NATURALIST have long been 
familiar with the contrivances and original constructions of a considerable 
number of American workers. Most microscopists, however, have con- 
fined their attempts to the production of accessories, believing, very judi- 
ciously, that the microscope as a whole could be more successfully made 
y more experienced hands. Of the comparatively few home-made 
microscopes, two recently published forms may serve as examples of the 
two extremes of ultra simplicity on the one hand and the best attained 
success on the other. In the form contrived by Mr. John Phin and-de- 
scribed in his Practical Hints, the body consists of a tube of stiff writ- 
ing-paper rolled several times around itself, pasted at the outer edge, 
and blackened on the inside. This tube slides, for focal adjustment, 
through another paper tube. A piece of looking-glass serves as mirror, 
of two-inch focus constitutes the ocular or eyepiece. The lenses are held 
in place in the tube by means of the bottoms of pill boxes perforated to 
allow the passage of light, while similarly perforated pill boxes are placed 
in the tube in proper position to act as diaphragms to reduce aberration 
by cutting off stray light. Such a microscope, at a cost of fifty cents, is 
conceded to be too imperfect to use for scientific study or even for instruct- 
ive amusement, its utility being not in the using but in the making of it. 
It is believed that a student by actually constructing such an instrument 
would gain a yery clear idea of the essential parts of the microscope, as 
well as a good understanding of the faults of simple work and uncorrected 
lenses. 
The more elaborate instrument. referred to is described by Mr, John 
1 This department is conducted by Dr. R: H. Warp, Troy, N. Y. 
