II. AIR PUMPS, ETC. 161 



use of the above-mentioned expression on seeing the arms of the firm of 5. v. 

 Musschenbroek. But how it happened that he did not see the other air-pump, 

 since he mentions a third air-pump, of Boyle's construction, still in existence, 

 is rather obscure, as De Voider, Sengucrd's predecessor in the professorship of 

 physics at Leyden, who himself laid the foundation of the establishment of 

 the Physical Science Cabinet at Leyden, must have worked in the same labo- 

 ratory. " There are given here (in the laboratory), as we were assured," 

 continues Uffenbach in his narratives, " ' Lectiones publicae ' four times a week 

 " by M. Senguerd; De Voider, however, it was stated, has had larger 

 " audiences, as he was more artful (' curieuser ') in his experiments." 



Senguerd did not deliver these lectures until after De Volder's retirement, 

 in 1705. De Voider died in 1709, and it is possible that the air-pump was 

 at that time in course of reconstruction, Scngucrd's air-pump, therefore, 

 as it is not to be found in the Physical Science Cabinet at Leyden, must, 

 in all probability, have been private property ; and it is possible that, like 

 many old instruments, it is still somewhere in private possession in Holland. 

 So long, however, as it is not discovered, the Cassel Museum may lay 

 claim to the distinction of having in its possession the air-pump with 

 the oldest four-way stop-cock. For although Senguerd had his air-pump 

 made in 1679, the description of it did not appear until 1685, when it 

 excited much attention. Christian Wolff, in 1718, had one constructed 

 exactly according to the same pattern, by Leupold at Leipsic, which may 

 still be seen in the Physical Science Cabinet of the University at Marburg. 

 It is very singular that Musschenbroek, in his manifold writings, never as 

 much as mentions Senguerd's air-pump. That, of course, this omission can- 

 not be construed into an argument against the priority of Senquerd is plain 

 from the subsequent remarks in the above-mentioned autograph notice, in 

 which it is stated that "in the year 1679 Senguerd and the same Samuel 

 " Musschenbroek had under consideration air-pumps of another kind, which 

 " were afterwards improved by my father, Jan van Musschenbroek, and by 

 " my brother " ("in den jaare 1679 heeft de Heer Senguerd met dienzelven 

 " Samuel Musschenbroek lucht pompen van een anderen aart bedagt, welke 

 " geduurig naderhand door inynen vader Jan van Musschenbroek, als door 

 " mynen broeder verbeterd zyn.") It seems as if family partiality had in- 

 fluenced him. 



The air-pump is accompanied by two powerful Magdeburg hemispheres 

 with which the experiments of Otto von Guericke, of the Kegensburg Diet, 

 were repeated at Cassel. 



604. Compression Machine, for throwing bombs. 



The Royal Museum, Cassel ; Dr. Finder, Director. 



This is one of the most ancient instruments in the possession of the 

 Cassel Museum. On the 16th November 1709, von Uffenbach saw it in the 

 Art Museum of Landgrave Karl. It was to serve for the purpose " of throw- 

 " ing lighted grenades through the air to a distance of more than 100 yards, 

 " with the usual effect." At that time some of its former defects had just 

 been repaired. " Twelve grenades can be thrown one after another with great 

 " rapidity. But, because the air is continually diminishing, the last, as may 

 " be easily conceived, do not go as far as the others." This instrument, 

 which acts on the principle of an air-gun, the brass ball carrying a funnel 

 upon which the grenades were placed, and by which also red hot shots could 

 be thrown without any danger to the men serving it, is of historical interest, 

 as it is a surviving witness of the joint labours of Papin and the Landgrave 

 Karl, and it even transports us to the midst of that catastrophe which put an 

 end to Papin's activity. It was a similar machine, with which Papin con- 

 templated throwing bomb shells by means of steam, which exploded in his 

 40075. L 



