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D.C. Ammeter (Weston)


The Direct Current Ammeter is mounted on a wooden base with a vertical wooden backboard that supports the instrument upright. At the top of the face is an arc-shaped linear scale calibrated in amperes, graduated in tenths between units and labelled in units of 0.1 from 0-1.0. The scale is covered with glass cover, and has a translucent white back. There is a needle on the scale. On the scale, beneath the arc, there is the words “USE WITH EXTERNAL SHUNT”.

There is raised lettering on the face of the instrument below the scale, this includes maker information and the serial number.

On the rear of the instrument, directly behind the scale is a light bulb socket, minus the bulb, apparently meant to illuminate the scale from behind. To either side of the socket are two electrical terminals, labeled “Positive” and “Negative”, with green plastic label-maker labels. These terminals are connected via yellow insulated electrical wires to the rear of the instrument.

Mounted on the vertical board at the rear of the instrument, there are also four sets of terminals. These are arranged in sets of two, each set affixed to a vertically oriented plastic piece, with one terminal above another. Each set is labelled with a different amperage with labels set on the top edge of the board: “1 AMP., 5 AMP., 10 AMP., and 20 AMP.. Each terminal (except for the 20 AMP. terminal) has an additional metal plaque on the plastic piece between the terminals, indicating amperage and what model it is to be used with.

Two small electrical terminals sit on the upper edge of the vertical board, in between the amperage labels.

Accession Number:

Alternative Name: Direct Current Ammeter

Primary Materials: Wood, Metal, Glass


Old inventory number = phy1026A-B.

Raised lettering on the face of the ammeter: “WESTON STATION AMMETER, NO. 10870”, “Made By WESTON ELECTRICAL INSTRUMENT CO., NEWARK, N.J., U.S.A.”. The face also has a small plate with patent information.

Dimensions (cm): Height = 36, Width = 33, Length = 24


Measuring amperage in electrical circuit; possibly a demonstration device.


Good. The metal is corroded in places. The wood backboard is marked and nicked. The glass of the scale is cracked in half.

Associated Instruments:


Weston Electrical Instrument Company, Newark, New Jersey, USA.

Date of Manufacture: 1892-1937


University of Toronto Department of Physics

Additional Information and References:

Historical Notes: