IN MEASURING PRESSURES IN A FLUID STREAM. 



79 



directed at an angle of 60° with the stream lines, and not at an 

 angle of 90° as is the usual custom. 



3170 



80 



Fig. I. 



Two tubes rigidly connected and having their axes at an angle 

 of 60° inserted into a pipe through which air is flowing will sepa- 

 rate velocity pressure from staticial pressures. One is to be so 

 turned in the stream that the reading of its gauge is a maximum. 

 It will indicate both pressures. The other indicates only the actual 

 pressure due to resistance of the pipe in advance of that point, if the 

 discharge is into the air. Such statical pressure differences at two 

 points along the pipe, will correspt)nd to voltmeter readings between 

 the points on a wire carrying an electric current. 



Another means of eliminating velocity effects is given by a de- 

 vice which I here present. 



A tube to carry the pressure .to the gauge, terminates at the 

 point where the pressure is to be collected, in a thin circular 

 disk, placed edge-wise in the stream. A parallel disk is secured to 



