The most delicate test objects for microscopes are the lines on the
feathers of butterflies or moths' wings, of which there are many
gradations; some easily demonstrated, and others only to be seen with
the most powerful reflectors, and to the best advantage by the simple
and uncondensed light of the lamp. The hair of a mouse is a very good
test object: it is best seen by daylight; the most difficult parts of
which are longitudinal lines in the transparent part of the hair, which
require high powers. The hair of the bat and seal are also fine tests.
The lines on the scales of the diamond beetle, &c. are excellent opaque
proof objects. The feet of flies are likewise very interesting.

* * * * *


_New Lilac Dyes._


Dr. Macculloch has lately produced two fine lilac dyes from plants of
domestic growth, not hitherto applied to this purpose. One is from the
berry of the Portugal laurel, and the other the black currant. The
simplest process with alum is all that is required for either; and as
far as his trials go, the best tint is produced by the former fruit.

* * * * *


_Dirty Windows._