II. AIR PUMPS, ETC. 165 



vapours, when by raising or lowering of the first tube, the level of the mer- 

 cury can be changed as required, and the resulting volume of gas observed. 



The apparatus can be easily adapted to all kinds of experiments, at 

 pressures either above or below that of the atmosphere. 



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. 



609. Double Cylinder Air Pump, with Babinet's stop-cock, 

 cylinder 170 mm. high, 60 mm. wide, with manometer and glass 

 plate of 200 mrn. diameter, on a mahogany board, with the 

 following auxiliary apparatus : 



1. Pair of Magdeburg hemispheres of glass. 



2. Electric egg, consisting of two parts, with arrangement 

 for carbon points. 



3. Double mill. 



4. Balloon, with bell. 



5. Balloon, for the gravity of the air. 



6. Fountain. 



7. Quicksilver. 



8. Ring. 



9. Dasimeter. 



10. Falling tube. 



11. Heron's ball. 



Warmbrunn, Quilitz, and Co., Berlin. 



610. Apparatus for Lighting, on the system of Dobereiner, 

 with contrivance for drying the gas. 



Warmbrunn, Quilitz, and Co., Berlin. 



61Oa. Water Vacuum Pump, invented by H. Sprengel in 

 1863. Hermann Sprengel. 



610b. Air Pump and two receivers, by Staudinger, Giessen. 

 Chemical Laboratory, University of Berlin; Prof. A. 

 TV. Hofmann, Director. 



611. Water Pump, either for exhausting or for compressing 

 air. Joseph Conquet. 



This apparatus can be used either in place of an air pump, or in place of 

 bellows. Water at a pressure of two atmospheres is required for working it. 



