from Orifices at different Temperatures. 



285 



on the discharge, and that, unless the small differences in the 

 experiments are errors of observation, the discharge is greater 

 at low temperatures. Whether this is due to the increase of 

 temperature increasing the contraction at the same time as it 

 diminishes the friction, could only be determined by much 

 more extensive experiments. 



For these experiments, when the level fell from A to B, 





292-75 



(4) 



and when the level fell from A to C, 



443-71 



t beinor in fifths of a second. 



(5) 



Coefficients of Discharge for Thin-edged Orifice. 



Values of c. 

 Temperature, 

 Fahrenheit. 



205 



205 



140 



65 



61 



61 



Fall of level 

 from A to B. 

 •5820 

 •5855 

 •5774 

 •5855 

 •5914 

 •5914 



Fall of level 

 from A to C. 



•5932 

 •5940 

 •5964 

 •5948 

 •5996 

 •5996 



205 



140 



62 



Mean Values. 



. . -5837 

 . . -5774 



. . -5894 



•5936 

 •5964 

 •5980 



These results seem to show that the temperature has hardly 

 any sensible influence on the discharge from orifices of this 

 kind. 



It will be seen that the results of these experiments do not 

 at all agree with those of Mr. Isherwood ; and although made 

 on a smaller scale, the author believes that if the influence of 

 temperature had been nearly as great as that stated by Mr. 

 Isherwood, it could not possibly have escaped detection. Mi- 

 nute errors in measuring the head or the size of the orifice 

 would sensibly affect the values of the coefficients obtained ; and 

 these may possibly be wrong to the extent of 2 or 3 per cent. ; 

 but these errors would not affect the relative values of the 

 coefficients in any sensible degree, and the author therefore 



