Accession No
2455
Brief Description
electromagnetic induction model to demonstrate induced current, designed by James Clerk Maxwell and made by Elliott Brothers, English, 1876
Origin
England; London; 449 Strand
Maker
Elliott Brothers [makers] James Clerk Maxwell [designer]
Class
electrical; demonstration
Earliest Date
1876
Latest Date
1876
Inscription Date
Material
wood (at least two types); metal (brass); plastic (ivorine); rope (string)
Dimensions
length of base 460mm; breadth of base 226mm; overall height 1095mm; length of each rod 600mm; overall width 1000mm; overall depth 480mm
Special Collection
Cavendish collection
Provenance
Transferred from Cavendish Laboratory, University of Cambridge, Cambridge, England. Designed and commissioned by James Clerk Maxwell for use as a teaching / demonstration device in the Cavendish Laboratory.
Inscription
‘ELLIOTT BROS.
449 STRAND
LONDON’ (ivorine plaque set into base)
‘E245’ (brass plaque on base)
Description Notes
Electromagnetic induction model to demonstrate induced current, designed by James Clerk Maxwell and made by Elliott Brothers, English, 1876.
Rectangular wooden base; two wooden uprights with bearings supporting horizontal axles connected to two wooden discs. These two axles are connected to each other through a differential gear at the centre. The intermediate gear of the differential coupling carries a flywheel consisting of four radial brass rods, each with a sliding brass cylindrical weight which may be fixed in position by a brass screw. One of the discs has a wooden handle and both have circumferential grooves holding strings. Tension is applied to the strings through elastic bands fastened to hooks on the base.
Condition good (brass rather marked and tarnished); complete (strings and elastic band are replacements). NOTE: If the model is to be used in experiments, extreme vigilance should be used as one of the four radial brass rods comes loose and drops out of the screw hole. (CW 06/10/2016)
References
Events
Description
In 1865, James Clerk Maxwell published “A dynamical theory of the electromagnetic field” which accounted for electric and magnetic phenomena as a single entity. It had been known for a long time that electricity, magnetism and light shared properties; however, each were attributed separate laws. Maxwell’s equations completed Ampère’s circuital law by introducing the displacement current term, and showed that these equations predicted light to move along electromagnetic waves.
When teaching in the Cavendish Laboratory, James Clerk Maxwell was fond of employing physical models in order to, as he put it, “present some phenomenon to the senses of the student in such a way that he may associate with it the appropriate scientific idea.” This particular model mechanically reproduced, through the rotation of two disks coupled by differential gears, the counter-intuitive behaviour of two magnetically-coupled electric circuits. Maxwell had the model specially built to his design and shipped from London.
17/03/2014
Created by: Allison Ksiazkiewicz / Joshua Nall on 17/03/2014
FM:40137
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