Menu Close

Control Hammer (Baird & Tatlock)


Five metal components are mounted on the wooden base. Two are mounted on the base itself and three are clamped to two vertical rods. Two of the components on the central rod are small electromagnetic coils. One component is an angled lever with a counterweight on one end and the “hammer” at the other. The fulcrum of the lever is fixed to one end of the wooden base. As the “hammer”, located at the end of the longer arm, is released by an electromagnet, it contacts two switches (an upper and lower contact), alternately opening and closing an electrical circuit, thus marking a set interval of time. The control time is varied by shifting a counterweight at the opposite end of the lever. There are two terminals attached to the front side of each end of the base.

Accession Number: 2012.psy.88

Alternative Name:

Primary Materials: Wood, Metal, brass


Old inventory number = “PSY 11”. Maker’s mark at the centre of the wooden base: “Baird & Taitlock (London) LTD., London, England. BLT”. Engraved on the bottom of the base: “4667”; Written in pencil “4647”.

Dimensions (cm): Height = 34, Width = 15, Length = 51


Used to calibrate precision timing devices such as the Hipp Chronoscope. The Gravity Chronometer performed the same function.


Good: Some wear, scratches, possible corrosion, fraying & tarnishing. Protruding rods loose.

Associated Instruments:

Manufacturer: Baird & Tatlock, London, England

Date of Manufacture: c. 1900


Department of Psychology, University of Toronto

Additional Information and References:

Historical Notes:

1) Titchener, E. B. (1905). <i>Experimental Psychology, a Manual of Laboratory Practice: Volume II, Quantitative Experiments, Part 1. Student’s Manual.</i> New York: MacMillan, p. 151

2) Stoelting, C. H. 1930. <i>Apparatus, Tests and Supplies for Psychology, Psychometry, Psychotechnology, Psychiatry, Neurology, Anthropology, Phonetics, Physiology, and Pharmacology.</i> Chicago, p. 77. <a href=”″>For a similar instrument.</a> Available from <i>The Virtual Laboratory: Essays and Resources on the Experimentalization of Life</i> (Max Planck Institute for the History of Science, Berlin)