milli-ammeter
Date: circa 1889
Inventory Number: 0219
Classification: Ammeter
Subject:
Cultural Region:
Place of Origin:
Dimensions:
9.4 × 14.4 × 16.2 cm (3 11/16 × 5 11/16 × 6 3/8 in.)
Description:
Milli-ammeter consisting of a core with a moving magnet and a permanent magnet below for zero adjustment. There are three rotating scales (5 - 0 - 5, 25 - 0 - 25, 250 - 0 - 250 amperes) on an ivory drum with contacts to change the resistence and a wedge-shaped wood, hard rubber and glass case with leveling screws. There are also three electrical connectors on the top of the instrument. Directions for use are printed on the back.
Signedon dial: The Chloride of Silver Dry Cell Battery Co.
Inscribedon base: 554
dial cover marked: Patented July 30th, 1889.
dial cover marked: Patented July 30th, 1889.
FunctionMeasurement of very small electrical currents. Printed instructions for this instrument (on card, see image) state that it was designed specifically for medical use, being especially compact and reliable.
Curatorial RemarksPatented July 30, 1889. A copy of instructions for its use is attached to card.
Core with moving magnet. Permanent magnet below for zero adjustment. 3 rotating scales on an ivory drum with contacts to change the resistance. Wedge- shaped wood, hard rubber and glass case with leveling screws.
Core with moving magnet. Permanent magnet below for zero adjustment. 3 rotating scales on an ivory drum with contacts to change the resistance. Wedge- shaped wood, hard rubber and glass case with leveling screws.