OtO PROCEEDINGS OF SECTION H. 



the adjustment of the governor, the speed of the air being taken 

 by the Revy meter. The results Avere not all strictly in accord. 

 A number of them made with the meter running alternately 723 

 and 1,402* revolutions per minute conformed very closely to the 

 formula/) z= C v f , thvis agreeing with neither Smeaton nor Crosby, 

 but lying somewhere between. Another set with the meter run- 

 ning alternately 523 and 1,284 revolutions gave ]) ■=. c v i-, thus 

 approaching Crosby's determination. 



These tests, based on an extreme range of velocity of less than 

 2h to 1 were felt to be insufficient to settle so important a matter. 

 An Osier's anemometer was therefore constructed, having a jjlate 

 1ft. square, and fixed upon a bicycle that was led or driven at 

 various speeds from 1 to 15 miles per hour. The pressures, how- 

 ever, proved too small to measure with certainty, and the area of 

 the plate was then increased to 3-6 sq. ft., when fairly definite 

 results were obtained, as shown : — 



The above results, though fairly consistent in themselves, and 



V- 

 corresponding to the formula P= — are so different to either 



Smeaton's or Crosby's as to suggest the need of further tests on a 

 much more extended range of velocities. 



The next series of experiments was intended to determine the 

 relation existing between the pressure on solids of various forms 

 and on thin plates or cards corresponding in area to the projection 

 of each solid. Thus a cube was compared with a card equal in 

 size to one of its faces, a cylinder with a rectangular card of equal 

 length and of width corresponding to the diameter of the cylinder, 

 a square pyramid with a triangle whose base was one basal side of 

 the pyramid and whose height equalled that of the axis of the 

 pyramid, a sphere with a circle of equal diameter — the object 

 being to obtain a modulus or number which when multiplied by 

 the presi-ure on the plate would give that on the solid. To detail 



* Each revolutio- of the meter corresponded to Ift. of motion of the air; 1,402 revolutionB 

 was therefore about sixteen miles per hour. 



