speed indicator probator

Datecirca 1925

Inventory Number1996-1-0259

ClassificationProbator

Subject

Supplier The Gaertner Scientific Corporation 1923-present

Collector Harold C. Ernst 1856 - 1922

Cultural Region

Place of Origin

Dimensionscase: 5 × 15 × 8.3 cm (1 15/16 × 5 7/8 × 3 1/4 in.)

Material

Accessoriesadvertising sheet for Gaertner Scientific Corp's probator [in instrument file with two photocopies]; tip for use as stopwatch; rubber tip

DescriptionThe probabtor consists of a white clock face mounted on black cylinder. There is a four number display counter to the left of clock face, with a silver adjustment screw attached to left end of the cylinder. The black cylinder is narrower to the right of the clock face, with a spindle protruding. A silver reset button is attached to a black knob at the top of clock face. The numbers "5" through "60" are printed around the clock face in intervals of five, with "60" in the top (12 o'clock) position. There are lines outside the numbers dividing the circle into sixty gradations. The clock hand is pointing to "60".

Signedunsigned

Inscribedon face: Probator / Breveté Patented on back: Made in Germany

FunctionThe primary function of this probator is to measure the speed of an engine. The spindle is pressed against the shaft of an engine and every revolution of the spindle increases the reading on the counter by one. The stopwatch runs for the duration of the time the spindle is pressed against the shaft, which, in combination with the number of rotations shown on the counter, gives the rpm.

ProvenanceFrom Paine Hall, department of Engineering, Havard University.