28 WAVES OF THE SEA 



in a boat not very far from the lee end, where I 

 was sure of a sufficient depth of water for the 

 purpose. Measurements with a wooden rule re- 

 peated during the course of half an hour gave 

 3 feet wave -length and a height from trough to 

 crest of about 2 inches. 



In ponds, therefore, we see that when the wind 

 raises waves at all they must be numerous, and 

 that even the longest must be a small fraction of 

 length of the series, and that the fraction decreases 

 as the length of the pond increases. The steepness 

 of the waves formed by wind upon ponds is also 

 found to be small as compared, for instance, with 

 the waves which may sometimes be seen caused 

 by obstructions in a river. Thus the height of the 

 waves in the Serpentine was only i-i8th of their 

 length. 



WAVES ON LAKES 



Coniston Water 



We now proceed to observations on a larger 

 sheet of water, the Lake of Coniston, or Coniston 

 Water, in Lancashire. They were taken near the 

 upper end of the lake, at a distance of 7 statute 

 miles from the lower end. The sheet of water is 

 narrow and nearly straight, the lower end about 



