Usage/History: Used to measure vacuum/pressure in
the range of 1-120 mm Hg. The instrument is operated by comparing
the heights of the two mercury surfaces in the U-shaped tube.
The mirrored scale may be adjusted to provide a direct readout
from the scale, eliminating the need for arithmetic.
Some contemporary/early descriptions of the manometer and
its use are provided below:
Manometers Duff, A. Wilmer.
A Text-Book of Physics (1921)
Description: The instrument is constructed of black
painted wood. The base has a quarter-round bead on the top edge
and is 6 5/8 x 5 3/8 x 3/4". It sits on four small rubber
feet. An upright, 12 7/8"t x 3 3/8"w, is attached with
its front face centered on the base. A 13-0-13cm scale, etched
into a mirror, is held with small brackets onto a wooden slide
on the left side of the upright. An open ended manometer tube
loops around the scale and then down to a stopcock which is in
turn connected to a "T" running along the bottom of
the upright. The manometer tuber is held in place with six small
trefoil pattern-end, nickel plated brass straps attached with
miniature screws. A nickel plated brass manufacturer's tag with
raised polished letters against a black background is pinned
in the center front of the base. The legend is as follows: TRADE PANTEC MARK/ PANTECHNICAL MFG. CO. / BERKELEY
-CALIFORNIA. There is an oval brass tag, stamped HUMBOLDT S-T-C / 2108, attached to the top
of the wooden stand with two brass pins. The instrument is in
fine condition noting that the mirror is in need of resilvering,
the wood shows through the paint on some edges and there is a
break, repaired with rubber tubing in the manometer tube between
the stopcock and the "T".
The catalog description is for a similar instrument sold
by the Braun Corporation in 1934.
