II. Alii PUMPS, ETC. 137 



" Jan van Musscheubrock, als door mynen breeder verbeterd zyn.") It 

 seems as if family partiality had influenced him. 



The air-pump is accompanied by two powerful Magdeburg hemispheres 

 with which at Cassel the experiments of Otto von Guericke, of the Regensburg 

 Diet, were repeated. 



604. Compression Machine. 



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



The Compression Machine for throwing bomb shells (air-mortars). 



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

 the musem at Cassel. On the 16th November 1709, already von Uffenbach 

 had seen it in the Art Museum of Landgrave Karl. It was to serve for the 

 purpose *' of throwing grenades, when already lighted, through the air for a 

 '* distance of more than a 100 yards, with the usual effect." At that time it 

 had just been repaired of some of its former defects. " Twelve grenades can 

 " be thrown one after another with great rapidity. But, because as the air is 

 " continually diminishing, the last ones, as may be easily conceived, do not 

 " go as far as the others." This instrument, which acts on the principle of an 

 air-gun, and by which also red hot shots could be thrown without any danger 

 to the men serving it ; the brass ball carried a funnel upon which the grenades 

 were placed is so far of historical interest as it is a surviving witness of 

 the joint labours of Papin and the Landgrave Karl, and it even transports 

 us in the midst of that catastrophe, which put an end to Papin's activity. A 

 similar machine, with which Papin contemplated throwing bomb shells by 

 means of steam, it was which exploded in his laboratory. " The other and 

 " greatest misfortune was that, as he had undertaken to shoot the same with 

 " water as with powder, he might easily have done great mischief, for as the 

 " machine prepared for that purpose exploded, not only a great part of the 

 " laboratory was demolished, several men mortally wounded (one amoug 

 " whom had his jaw-bone carried away), but even Landgrave Karl himself, 

 " who is a very curious lord, intent upon seeing and examining everything 

 " minutely, might have been hit, and have lost his life, if not His Highness had 

 " been detained by mere accident by other affairs and come to the laboratory 

 " later, on which occasion Papin was dismissed from his service." 



605. Suction Pump, on an iron stand. 



Ferdinand Ernecke, Berlin. 



605a. Suction Apparatus. Two small pieces of apparatus 

 to illustrate the deficiency of pressure attending a high velocity 

 in a stream of air. Lord Rayleigh. 



By blowing through the electrotyped copper tube a suction of 6 inches of 

 mercury may be realised at the narrow part. 



In the second arrangement the novelty consists in the cap at the end of the 

 brass tube, by which the efficiency is increased. 



607. Two large Magdeburg Hemispheres of copper. 



Professor Dr. H. Weber, Brunswick. 



The two large hemispheres of copper are those of which Otto von Guericke 

 states, in page 104, Tab. XI., that after their evacuation they could not be 

 separated by the united strength of 16 horses. They have a diameter, as 

 mentioned in the work alluded to above, of nearly f Magdeburg ells, or, 

 according to a second more exact statement, 0'67 Magdeburg ells. 



The two smaller hemispheres of brass were used for experiments with 

 weights (page 106, Tab. XII.). 



608. Two smaller Magdeburg Hemispheres of brass. 



Professor Dr. H. Weber, Brunswick. 



