210 OUTLINES OP NATURAL PHILOSOPHY, 



stream measured in degrees be called #, and if the 

 resistance to the base of the wedge be 10000, the 

 resistance to the wedge itself will be 



10000 x cos a* + 3.153 x 



BOSSUT Hydrod. torn. n. 1019, & 1022. 



This formula, however, is to be considered only as an 

 approximation to the truth. It is entirely empirical, 

 and only agrees with experiment, when x is nearly a 

 right angle, or when the angle i is very small. 



500. Supposing the resistance to oblique sur- 

 faces to vary, as the square of the sine of the incli- 

 nation, the resistance to a sphere is half the resist- 

 ance that would be made to the circumscribed cy- 

 linder moving in the direction of its axis. 



NEWTONI Prin. Math. lib. n. prop. 34 



This proposition cannot be expected to hold accurate- 

 ly, as it is derived from a principle that is acknow- 

 ledged to be erroneous. The propositions concern, 

 ing the solid of least resistance, are faulty for the 

 same reason. In general, though the theory of the 

 perpendicular percussion and resistance of the dense 

 fluids, agrees sufficiently with experiment for all 

 practical purposes, that of their oblique percussion 

 and resistance, as it stands at present, is not to be 

 relied on. The experiments relative to percussion 



are 



