Usage: "Designed especially for use in elementary
work." This box would be used as a standard resistance in
laboratory work in schools. Resistance values, to 0.2%, are adjusted
by removing the brass pegs. The box is constructed with the pegs
in parallel with precision bifilar wound resistance coils-with
the peg in place the current flows through the peg ( 0), when
removed the current flows through the resistor.
Description: The instrument is contained in a one
piece cast bakelite case, the top of which has been ground flat.
The binding posts are of polished brass with captured knurled
nuts. The resistance value is adjusted by inserting plugs (tapered
brass with black bakelite handles) into holes connecting brass
lugs which are embedded into the top surface of the case. The
total resistance of the box is 11,100 ohms divided as follows:
10, 20, 30, 40, 100, 200, 300, 400, 1000, 2000, 3000, & 4000.
The name Cenco is engraved into the top center of the case. The
name and resistance values are all white filled. There is a red
ink stamp near the binding posts, consisting of a circle within
a circle and the figures c.s. / 1 inside the center circle. The
bottom of the case is covered by a perforated aluminum sheet,
held on by four brass screws at the corners, u.s. pat. 1,781,802
is ink stamped in black 1/2" figures across it.
Research: A similar instrument is shown on p 1300
of the 1950 Cenco Catalog (J150) as item 82785. The illustration
appears to show a black box with brass binding posts as well.
The 1960 (J-300) Cenco Catalog shows plastic binding posts and
grey plugs for this instrument (P 758, item 82785).
