APPENDIX ('. 



115 



Jn addition to determining the position of the center of pressure for a square plane, 

 Kummer extended his experiments to the case of differently shaped rectangles, and his 



results with these are strikingly suggestive. It has been pointed out in chapter V] thai 

 above and below an angle of about 30° there is a reversal in the relative amounts of the 

 pressure on inclined rectanglar planes of different shapes; the tabulated results of Kummer 

 exhibit a similar reversal in the position of the center of pressure, of which the following 

 may be given as an example: 



Distance of a nb r ofpres&m from o nU r of plane. 



For small angles the position of the center of pressure is further from the center of 

 figure in the 180 x 180 mm. plane than in the 00 x ISO mm. plane, while for 45° this 

 relation is reversed. It appears, therefore, that the reversal in the amount of pressure, 

 brought out in the experiments presented in this memoir, finds its counterpart in a corre- 

 sponding reversal in the position of the center of pressure exhibited in the work of Kummer. 

 It is believed that in this striking analogy may be found a key to the move complete 

 rational and deductive treatment of these inseparably related problems. 



