132 SEC. 5. MOLECULAR PHYSICS. 



606. Otto von Guericke's original Air Pump. 



" Collegium Carolinum" Polytechnic School at Bruns- 

 wick, Professor Dr. H. Weber. 



The earliest reliable information respecting Otto von Guericke's original 

 apparatus is contained in a list of the physico-chemical apparatus of the 

 Collegium Carolinum, at Brunswick, of the year 1816. In this list it is stated 

 that these apparatus were obtained from the inheritance left by Aulic Coun- 

 cillor Beireis, in Helmstedt. According to a special ordinance of His 

 Highness Frederick Wilhelm, Duke of Brunswick, dated 8th October 1814, 

 the collection of physical, mathematical, and astronomical instruments derived 

 from the inheritance left by Beireis, physician in ordinary, at Helmstedt, was 

 exhibited in the rooms, and by a later ordinance dated 9th March 1815 incor- 

 porated with the collections of the ducal Collegii Carolini. The air-pump has 

 been preserved unaltered, with the exception of the lever and the piston attached 

 to it, the former having been replaced by a new one of the same construction, 

 and the latter by a wooden one, in the year 1 864. The pump has been described 

 and faithfully represented by a drawing in a work published by Otto von 

 Guericke, entitled " Ottonis de Guericke Experirnenta nova (ut vocantur) 

 Magdeburgica de vacuo spatio Ainstelodani," 1672, cap. IV. p. 75, Tab. VI., 

 in which work he also (p. 122) successfully refuted the assertion of Augustus 

 Hauptmannus, doctor of medicine, in his " Berg-be-deneken, anno 1658, 

 Lipsiae," "that it would not be possible to either angel or devil to 

 bring about a vacuum." This work is in the possession of the ducal library, 

 at Wolfenbiittel. But, previous to this air-pump, Otto von Guericke had con- 

 structed one more simple, consisting of only one cylinder and a piston, which 

 is said to be in the library- at Berlin. The difficulty, however, connected 

 with the motion of the piston, the resistance of the air against the free piston 

 being so great that it required two strong men to pull it out repeatedly, p. 75, 

 induced him to contrive their second improved construction. The air-pump 

 plateau at present in use was unknown to Otto von Gueiicke. In order to 

 produce a vacuum, he employed a hollow copper ball with stop-cock,* which 

 Avas placed on the pivot of the barrel. It was evacuated, and screwed on 

 to other vessels, whereby, by repeating this manipulation, the latter was 

 evacuated likewise. The pail of tin-plate attached to the lower end of the 

 barrel, as well as the copper bowl fastened to the upper end of the barrel, 

 were filled with water or oil, in order to effect thereby a greater tightness. 



622. Diagram of Von Guericke's Air Pump. Invented 

 1654. A. Galletly, Edinburgh. 



It consisted of a globe of copper, with a stopcock, to which a pump was 

 fitted. 



The pump-barrel was entirely immersed in water to render it air-tight. 

 This was the earliest of all air-pumps. 



623. Diagram of the First English Air Pump, constructed 

 in 1658-59 by Hooke and Boyle, but mainly by the former. 



A. Galletly, Edinburgh. 



As shown in the diagram, it had a single barrel, in which was a piston 

 worked by a rack and pinion. In working it the valve G of the cylinder was 



* This ball (page 88, Tab. VIII.), as well as a pair of still larger Magdeburg hemi- 

 spheres, nearly an ell, Magdeburg measure, in diameter, which 24 horses had not the 

 power to separate (page 105), and, lastly, a copper boiler with inserted piston, which, 

 when the air below the same was withdrawn, 50 men were not able to lift or to pull up 

 (paw 109, Tab. XIV.), are likewise enumerated in the list, but no longer to be found. 



