Moll Micro Galvanometer

Astronomy

Accession Number: 2018.ast.68 (DAA-0023)

Description:

This object is a Moll Micro Galvanometer. The stand consists of a circular base with tripod legs, each adjustable with a screw. At the front of the base there are two electrical contacts with plastic knurled knobs on top to attach wires. Behind there is a horseshoe magnet mounted vertically, with the two ends of the magnet pointing upwards. The suspension tube of the galvanometer is mounted upright between them. The galvanometer is attached by two small screws.

The suspension tube is a metal about 14cm long and cylindrical, with ends that narrow at one end to a knurled knob and at the other to a rounded point. There are various other metal appendages emerging from the cylinder. In the centre of the cylinder there is a circular window. Visible through the window there is a small round mirror.

Attached magnetically and bridges the ends of the magnet is a rectangular piece of metal, with two shiny handles on each side. This is covered with green felt on the inner surface.

Alternative Name:

Mirror galvanometer, Galvanometer suspension tube.

Primary Materials:

Metal, Iron Alloy, Plastic, Fabric, Felt.

Markings:

On the flat surface of the stand: “KIPP DELFT-HOLLAND”.

On the barrel of the galvanometer: “1247”.

Dimensions (cm): Height: 19, Diameter: 15.5

Function:

A mirror galvanometer is for the measurement of very small changes in current. Light is reflected on the small mirror in the interior. This mirror is connected to a fine wire which is affected by tiny shifts in electrical current. The amount of the deflection of the mirror can be used to measure electrical current.

This object may have been used with the Moll recording microphotometer, “for investigation of photographed spectra.” (“Moll recording microphotometer”, Journal of Scientific Instruments, Vol. 12, No. 12, (1929) pgs 392-394: 392)

Condition:

Excellent: The object has few signs of damage. The top of the galvanometer tube is very slightly tarnished/dirty.

Associated Instruments: 2018.ast.67.3

Manufacturer: P.J. Kipp, Delft, Holland

Date of Manufacture: 1930s-1940s

Provenance:

This object was likely moved from the David Dunlap Observatory in Richmond Hill in 2008, upon the sale of the observatory. It was stored at the Department of Astronomy and Astrophysics until 2017, when it was moved to a new storage location in McLennan Physical Laboratories.

Additional Information and References:

This galvanometer suspension tube came in a specialised box. This is catalogued under 2018.ast.67.3, alongside two other identical boxes.

1929 Journal of Scientific Instruments article on the Moll recording microphotometer, which included the Moll Micro galvanometer as a component.