Being all of wood, it is easily made by any one who can use a few tools,
the only bit of lathe work necessary being the turned shoulder, K, of
polar axis. A is the baseboard, 9 in. by 5 in., near each corner of
which is inserted an ordinary wood screw, S S, for the purpose of
leveling the base, to which two side pieces are nailed, having the
angle, _x_, equal to the co-latitude of the place. On to these side
pieces is fastened another board, on which is marked the hour circle, F.
Through this board passes the lower end of the polar axis, having a
shoulder turned up on it at K, and is secured by a wooden collar and pin
underneath. On to the upper part of the polar axis is fastened the
declination circle, C, 5½ in. diameter, made of ¼ in. baywood, having
the outer rim of a thin compass card divided into degrees pasted on to
it. The hour circle, F, is half of a similar card, with the hours
painted underneath, and divided to 20 minutes. G is the hour index. D is
a straight wooden pointer, 12 in. long, having a piece of brass tube, E,
attached, and a small opening at J, into which is fixed the point of a
common pin by which to set the pointer in declination. H is a nut to
clamp pointer in position. By this simple toy affair I have often picked
up the planet Venus at midday when visible to the naked eye.--_T.R.
Clapham in English Mechanic_.
[Illustration: A STAR FINDER.]
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The best mode of finding or tracing trichinae in pork by means of a
microscope is the following: Cut a very thin longitudinal slice of the
muscle by means of a very sharp knife or razor. Press it between two
glass slips, and examine by transmitted light, The coiled trichinae may
be readily distinguished from the muscle fiber.
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