26 SCIENCE IN SHORT CHAPTERS. 



the differing appearance, I at last pointed it out to the captain, 

 and asked him the meaning of it. * The cooks,' said he, 

 1 have, I suppose, been just emptying their greasy water 

 through the scuppers, which has greased the sides of the ships 

 a little.' And this answer he gave me with an air of some 

 little contempt, as to a person ignorant of what everybody else 

 knew. In my own mind, I first slighted the solution, though 

 I was not able to think of another." 



Franklin was not a man to remain prejudiced ; he accord- 

 ingly investigated the subject, and the results of his experi- 

 ments, made upon a pond on Clapham Common, were com- 

 municated to the Royal Society. He states that, after drop- 

 ping a little oil on the water, " I saw it spread itself with surpris- 

 ing swiftness upon the surface, but the effect of smoothing the 

 waves was not produced ; for I had applied it first upon the 

 leeward side of the pond, where the waves were largest, and 

 the wind drove my oil back upon the shore. I then went to 

 the windward side, where they began to form ; and there the 

 oil, though not more than a teaspoonful, produced an instant 

 calm over a space several yards square, which spread amazingly, 

 and extended itself gradually till it reached the lee side, mak- 

 ing all that quarter of the pond (perhaps half an acre) as 

 smooth as a looking-glass." 



Franklin made further experiments at the entrance of Ports- 

 mouth Harbor, opposite the Haslar Hospital, in company with 

 Sir Joseph Banks, Dr. Blagden, and Dr. Solander. In these 

 experiments the waves were not destroyed, but were converted 

 into gentle swelling undulations with smooth surfaces. Thus 

 it appeared that the oil destroys small waves, but not large 

 billows. 



Franklin's explanation is, " that the wind blowing over 

 water covered with a film of oil cannot easily catch upon it, so 

 as to raise the first wrinkles, but slides over it and leaves it 

 smooth as it finds it." 



Further investigations have since been made which confirm 

 this theory. The first action of the wind in blowing up what ( 

 the sailors call " a sea," is the production of a ripple on the 

 surface of the water. This ripple gives the wind a strong hold, 

 and thus larger waves are formed, but on these larger there are 

 smaller waves, and on these smaller waves still smaller ripples. 

 All this roughness of surface goes on helping the wind, till at 

 last the mightiest billows are formed, which then have an 

 oscillation independent of the wind that formed them. Hence 



