134 Mr. Willis on the Pressure of a 



at a maximum, then to a second neutral circle Cc, and then 

 again to one Dd, where the condensation attains a second max- 

 imum. Taking these circles as the most characteristic points of 

 the phenomenon, I have, in Tables V. and VI. given their radii 

 together with the amount of the maximum rarefaction and con- 

 densation at different distances of the disc from the plate, and 

 with various orifices and pressures. Table IV. shews the pressure 

 indicated by the gage at different distances from the center of 

 the disc, and at different distances of the disc from the plate. 



