Curator's Choice: A Selection of Instruments from the Museum Stores

Richard Paselk, Curator

Precision Double-Hook Torsion Micro-Balance

This direct reading (to 0.5 mg) dial-operated balance is a lovely example of mid-twentieth century design with a Art-Deco feel. It was designed for rapid repetitive weighings of small objects from 0–250 mg to ±0.25 mg. The double-hook allows weighings up to 1.25 g in 250 mg intervals by adding appropriate weights to the second hook. A 250 mg calibration weight, hook, ivory tipped tweezers, adjustment screwdriver (all in drawer) and two aluminum pans (in balance compartments) are included. The cast aluminum case is finished in black enamel, external metal parts are nickel-plated. A bulls-eye level is mounted in the top of the case.

Usage

This balance is designed for the rapid determination of weights of small objects (<1 gm) to a reasonably high precision (±0.25 mg). Weights from 0–250 mg are determined directly by adjusting the dial, weights from 250–500 mg are determined by adding a 250 mg weight included in the accessories drawer of the balance to the weight-hook. Compare to the Roller-Smith Double-Hook Balance. The catalog description is from: Scharr Scientific Company, Selected Laboratory Equipment and Chemicals 63/64.Chicago (1963) p40.

Description

This instrument is a low capacity precision torsion balance. The black japanned metal case is “lollipop” shaped, with the pedestal flaring out to sit upon a flat base with two adjusting screw feet extending out to the sides in front. A small drawer in the column contains a forceps, range extension & calibration weights, and a jewelers screwdriver. An image of the open drawer shows the open aluminum box for the weights etc.

The instrument is high, and wide across the upper case. A fine control (planetary gear?) dial (3 1/4”dia with a 2”dia inner knurled handle) in the center of the case turns a large dial (≈ 6 1/2”dia) through a range of 250mg x 0.5mg at the rate of 40mg/turn. An arrest knob is placed below this dial, just above the transition to the pedestal. Balance is achieved through aligning a floating needle against a scribed line on a small, mirrored scale. There are enclosed sample and weight compartments on the opposite sides of the upper case. In each case a window allows viewing of the contents. All exposed metal parts are nickel-plated. There is a bullseye level at the top of the case. The number 1711 (serial number?) is stamped on the underside of the base of the instrument.

There is a manufacturers tag riveted to the case below the dial: august • sauter / n. y. inc. • n.y.c. usa. written around the circular ASE symbol; and a silver distributor’s decal on the pedestal: EGCo / The EMIL GREINER Co. / serving the laboratory for over 60 years / 20 - 26 North Moore St. / New York 13.

Research

A series of large balances (200-1000 gm) of similar design by Sauter are shown (items 11730) on pg 43 of the Braun-Knecht-Heimann-Co. div of Van Waters & Rogers, Inc, Catalog No. 63 (©1961). A similar balance by Torsion Balance Co is also described on pg 42 of this catalog. Sauter was established in 1856 in Ebingen Germany.**

* The Fungal Genetics Stock Center was located at HSU during the tenure of Dr. Ray Barrett, Dean of the College of Science from 1970–1983. The balance was donated to the museum in 1984 when the Stock Center moved to another institution.

** MacNevin, William Marshall, The Analytical Balance, Its Care and Use, Handbook Publishers, Inc., Sandusky, Ohio, (1951), pg. xi.

© R. Paselk 2013, Last modified 3 January 2021