162 MR. H. WILDE ON THE VELOCITY 



The ordinal numbers at the head of the table indicate the 

 atmospheres in the receiver when the discharge was made, 

 commencing with vacuo ; and the time of each discharge, 

 in seconds, is shown against the pressure in the discharg- 

 ing and receiving cylinders respectively. The times in the 

 second and third vertical columns are obtained from those 

 in Tables I. and IV., when the discharge was made into a 

 vacuum and into the atmosphere. On examining these 

 results, commencing with the lower pressures, it will be 

 seen that for two atmospheres of absolute pressure, the 

 time of discharge (43 seconds) was the same for a vacuum 

 as it was when made into the atmosphere, as has already 

 been demonstrated. It will also be seen that a pressure 

 of two atmospheres in the receiver acts as a vacuum to 

 four atmospheres in the discharging cylinder. This is evi- 

 dent from the equality of the time (20 seconds) when the 

 discharge was made into one atmosphere or into a vacuum. 

 The like ratio will also be observed up to three atmo- 

 spheres in the receiver, which act as a vacuum to the dis- 

 charge of six atmospheres of pressure from the small 

 cylinder. As the pressure in the receiver was increased, 

 the diminution of resistance of the recipient atmospheres 

 becomes still more marked, till for the highest pressures 

 we have the remarkable phenomenon of six atmospheres 

 acting as a vacuum to the discharge of nine atmospheres 

 of pressure. That this peculiar relation of the discharg- 

 ing and receiving atmospheres has not reached its full 

 limit will be obvious from a comparison of the numbers in 

 the Table, from which it would appear that, for pressures 

 exceeding those used in these experiments, the resistance 

 of the recipient atmospheres would be still further dimin- 

 ished correlatively with an increase in the amount of 

 discharge. 



