1901) MICROSCOPICAL JOURNAL. 325 
ing at them through a pinhole near the eyepiece, a me- 
thod which I followed for some time. This, though it 
does away with the shifting, reduces the light very much. 
It is also possible to view the spectra by screwing an 
objective into the lower end of the sliding draw-tube, 
with eyepiece in position at the upper end, and then 
focussing down on to the upper focal plane of the object- 
ive, but this is a cumbersome business. Latterly I have 
employed a method which is exceedingly convenient and 
efficient. The diffraction spectra, as is known, are not only 
formed in the focal plane of the objective, but are reform- 
ed just above the eyepiece, and may there be viewed by 
means of alens. So I have mounted in a short tube the 
objective of one of the cheap toy microscopes, which is 
in effect a lens of about a t inch focus stopped down to 
an actual aperture of about 1mm. The diffraction spectra 
ocular, as we may call it, when placed on the ordinary 
eyepiece of the microscope, on the cap of which it fits 
shows the specira splendidly, magnifying them at the 
same time. It gives plenty of light, and the spectra can 
not shift. I can strongly recommend the arrangement 
to those who cultivate the useful habit of studying the 
spectra, 7. e., the optical effect produced by na object, as 
‘well as the object itself.—Quekett Club. 
Sketch of J. D. Whelpley. 
Born at Battle Creek, Mich., May 24th, 1861, Dr. Whelpley 
has just turned 40, To enumerate even the larger portion 
of the things which he has done during the comparatively 
few years of his existence would filla volume, so no attempt 
_ will be made in this slight sketch to touch his career except 
at the high places. To show the strength of heredity it 
may be well to state in the first place that the subject of 
this notice is descended from a family of physicians, his 
father, grandfather and great-grandfather having practiced 
