Maker: Carl Stollnreuther. He founded in Munich, in 1845, a firm producing scientific instruments.

Inventor: Georg Jolly, b? - d.1866. University student, he died shortly after having designed this model of pump.

Date: 3rd quarter 18th century

Description

The mercury air-pump designed by  Johann Heinrich Wilhelm Geissler was described in 1858. It had no pistons but used mercury, as in Torricelli’s original experiment. The vacuum was actually obtained by raising and lowering a column of mercury. The pump was made of two glass vessels, one mobile and one fixed; air was rarefied in the latter.  Geissler’s pump was modified and improved throughout time and the present model, described in 1866 by Georg Jolly is one of the numerous variations that were proposed. It is also made of two vessels, connected by a rubber tube, but it is characterized by a mechanical device of a winch and pulley, to raise and lower the movable vessel. Thanks to a spring acting on a gear, it is possible to fix this container at any desired height. According to Thompson, the idea of the handle-pulley contrivance, introduced for the first time in Jolly’s model, was quickly adopted by many makers, and variations of it can actually be found on most successive models.

In this pump, an iron tube mounted at the top of the fixed vessel connects the latter to the plate on which the  experiments in rarefied air were to take place. This tube is equipped with a three-way cock connected to an horizontal tube ending with an U-shaped tube, now broken, that served as a manometer.

To work, the vessels and the connecting rubber tube were partially filled with mercury. When the mobile container was lowered, the level of the mercury lowered in the other branch of the rubber tube, so that air was rarefied in the fixed vessel. When the mobile vessel was raised, mercury raised in the fixed vessel, thus expelling the air outside. The three-way cock served to change the connections throughout the different working phases. Thanks to another three-ways cock fixed on the horizontal tube, it was possible to isolate the manometer or to connect the pump with a system of vertical tubes, through which one could introduce small quantities of gas.

Inscription: 11 C. Stollnreuther München

Materials and techniques: wood/glass/brass/rubber/iron

Dimensions: height 147 cm, width 61 cm, depth 58 cm

Keywords: mechanics, pneumatics

University of Padua, Museum of the History of Physics

Cat. Number: 743

Exhibitions

• "Bagliori nel vuoto. Dall'uovo elettrico ai raggi X: electricity e pneumatica dal Seicento ad oggi", Padua, Botanical garden, 1 February-30 June 2004

Bibliography

• Adolphe Ganot, Traité élémentaire de physique expérimentale et appliquée et de météorologie, 14 ed., Paris, 1870
• Jules Jamin e M. Bouty, Cours de physique de l’Ecole Polytechnique, 4 vols., Paris, 1878-1883
• Georg Jolly, Ueber eine neue Einrichtung der Quecksilberluftpumpe, “Repertorium furphysikalische Technik fur mathematische und astronomische Instrumentenkunde”, vol.1, 1866, pp. 144-148, pl. XIX
• Silvanus P. Thompson, The development of the mercurial air pump, “Electrical Review”, 1187, pp. 587-590.