similar substance, to which is at- taining a ring, which in the present case is made surface of the cap, tached a mouth or nose piece, the latter being partly revoluble, and arranging in these rings auxiliary lenses as shown in. the shown in Fig. 3. The nose and mouth piece are inter- of… … vessels, as shown in one of the small views, which are ASTIGMATIC EYEPIECE FOE OPTICAL INSTRUMENTS, in communication with the interior of thetube. They It is a remarkable fact, not generally known to per- are designed to collect the rain, dew, or other moisture, sons unacquainted with the business…
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