Ramsden-type plate electric machine
Date: 1864-1877
Inventory Number: DW0300
Classification: Electrical Machine
Subject:
Maker: Eugène Ducretet (1844 - 1915)
Cultural Region:
Place of Origin:
Dimensions:
140 x 96 x 54.7 cm (55 1/8 x 37 13/16 x 21 9/16 in.)
Bibliography:
Catalogue des instruments de précision de E. Ducretet & Cie
Description:
The large glass disk is fixed at the center and rotates with the help of a crank. The disk is compressed by four cushions on springs (Steiner model). The disk passes through two connectors made in the shape of a horse shoe. They are terminated by a piece-like comb and teeth made of brass. These two connectors are attached to two horizontal brass tubes. The latter are connected in turn to a set of brass tubes on which electricity is gathered and used for experiments.
This system of communicating brass tubes is supported by four insulated glass pillars. Above the name plate there is a small removable brass pin used to de-electrify the machine at the end of an experiment (from pin to body to the earth). The whole structure is supported by a table on four legs.
This system of communicating brass tubes is supported by four insulated glass pillars. Above the name plate there is a small removable brass pin used to de-electrify the machine at the end of an experiment (from pin to body to the earth). The whole structure is supported by a table on four legs.
In Collection(s)
Signedon name plate: E. DUCRETET, Rue des Ursulines 21, PARIS
FunctionAn electrostatic machine is an instrument used to produce electricity for conducting serious as well as pedagogical, fun and surprising experiments. The electricity is produced by friction, in this case by the glass disk rotating on the four spring cushions. The electricity is gathered by the comb and teeth device by way of induction and is accumulated on the surface of the brass sphere in the center of the machine.
Curatorial RemarksHere is how Ducretet described this machine in his 1870 Catalogue: "#1082 Machine électrique, même modèle, ayant [un plateau de] 50 centimètres 250 FF... Machine électrique de Ramsden, sur table en noyer verni naturel, ou acajou, deux conducteurs; coussins à ressorts, système de Steiner. Deux quarts de cercle en taffetas; électromètre à cadran, boule pour la répulsion des corps légers..." The quadrants and electrometer appears to be missing from this example.
Primary SourcesEugène Ducretet, Catalogue des Instruments de précision de E. Ducretet (élève de M. Froment). Constructeur d'instruments de précision pour les sciences et l'industrie , new ed. (Paris, 1870), #1082.
E. Ducretet et Cie, Petit catalogue des instruments de précision de E. Ducretet et Cie (élève de M. Froment) (Paris, 1880), part 3, 16, no. 2111 or 2112.
E. Ducretet et Cie, Petit catalogue des instruments de précision de E. Ducretet et Cie (élève de M. Froment) (Paris, 1880), part 3, 16, no. 2111 or 2112.