Fig. 6. AIR-PUMP. 



THE ATMOSPHERE. 



1. Experimental proofs of the weight of the atmosphere. 2. The bladder 

 glass. 3. Pressure equal in all directions. 4. Pressure of air in a 

 room explained. 5. Magdeburg hemispheres. 6. Suction with tube. 

 7. Pascal's experiment at Rouen. 8. Horror of a vacuum. 9. 

 Galileo and the pump-makers. 10. Torricelli's celebrated experiment. 

 11, Pascal's experiment on the Puy-de-d6me. 12. Actual pressure 

 of atmosphere ascertained. 13. Height of an atmosphere of uniform 

 density. 14. Vastly greater height of an elastic atmosphere. 15. 

 Air less and less dense in ascending. 16. Effects of atmospheric 

 pressure. 17. Boy's plaything of a sucker. 18. Flies walking on 

 ceiling. 19. Respiration. 20. Action of bellows. 21. Ventpeg lid 

 of tea-pot. 22. Pneumatic ink-bottle. 23. Syringes. 24. Ex- 

 hausting syringe. 25. Rate of rarefaction. 26. Absolute vacuum 

 cannot be obtained. 27. But may be indefinitely approached. 28. 

 Air-pump. 29. Condensing syringe. 30. Condenser. 



1. IN a former part of this series some of the most conspicuous 

 properties of the atmosphere were explained, and among these its 

 weight and pressure.* "We now propose to resume this subject, 

 and to explain the expedients by which the weight, elasticity, and 

 other mechanical properties of the atmosphere are ascertained. 



* Common Things Air, vol. ii. p. 1. 



LARDNER'S MUSEUM OF SCIENCE. H 97 



No. 55. 



