SNOW-WAVES AND SNOW-RIPPLES 163 



stern. If a wedge-shaped solid body has to be 

 driven through another sohd the business end of 



^- 



Fig. 17 



Profile (dotted) and central longifcudinaJ section of the same drift 



the wedge is the thin end, but if a soHd has to 

 be driven through a Hquid the blunt end is the 

 business end.' 



The plan of a snowdrift formed by a clump of 

 bushes, of which a photograph and drawings are 

 given, is the whole of the head or " entrance " 



Fig. 18 

 Section across the dotted line of Fig 16 



and part of the " tail " or " run " 2 of the eddy- 

 curve (Figs. 16, 17, and 18). 



^ Thus the wings of birds have " thick leading edges " 

 (see Nature^ June 19, 1913, Wilbur Wright Memorial Lecture 

 by Mr. Horace Darwin). 



^ " Entrance " and " run " are terms used by naval architects 

 for the swelling fore part and the narrowing after part of a 

 ship. The lines of the submerged portion of a ship which 

 are integrated in the "curve of immersed areas" should have 

 a bluff entrance and a fine run, which is also the form given 

 to non-rigid airships. 



