ON THE MOTION OF WAVES. $63 



and 2dly. to prevent its driving those which are already raised with 

 so much force, as it would if I heir surface were not oiled. 



Such experiments at sea are evidently attended with a great many 

 difficulties; but in particular cases essential advantages may be de. 

 rived from the use of oil, and several instances of its having been of 

 very great service, are recorded *. " We might," says Dr. Franklin, 

 " totally suppress the waves in any required place, if we could corne 

 at the windward place, where they take their rise. This in the 

 ocean can seldom, if ever, be done. But, perhaps, something may 

 be done on particular occasions, to moderate the violence of the 

 waves, when we are in (he midst of them, and prevent their break- 

 ing, where that would be inconvenient. 



" For when the wind blows fresh, there are continually rising on 

 the back of every great wave, a number of small ones, which roughen 

 its surface, and give the wind hold, as it were, to push it with greater 

 force. This hold is diminished by preventing the generation of those 

 small ones. And possibly too, when a wave's surface is oiled, the 

 wind, in passing over it, may rather in some degree press it down, 

 and contribute to prevent its rising again, instead of promoting it.''. 



Light, volatile, or etherial oils, like ether, spirit of turpentine, &c. 

 do not possess the same property as fat oils, such as olive oil, lin- 

 seed, rape-seed oil, train oil, &c. 



\_Caiallo. Nat. Hist. 



* Mr. Tengnagcl, in a letter to Count Bentinck, dated Batavia, January 

 the 5th, 1770, says, " Near the Islands Pawl and Amsterdam, we met with a 

 storm which had nothing particular in it worthy of being communicated to you, 

 except that the Captain found himself obliged, for greater safety in wearing 

 the ship, to pour oil into the sea, to prevent the waves breaking over her, 

 which had ail excellent effect, and succeeded in preserving us." Phil. Tran, 

 vol. Ixiv. p. 456. 



It has been remarked in Rhode Island, that the harbour of Newport is ever 

 smooth whilst any whaling vessels are in it ; which is, in all probability, owing 

 to the fish-oil that may come out of them. 



It is said to be a practice with the fishermen of Lisbon, when about to return 

 into the river (if they see before them too great a surf upon the bar, which 

 they apprehend might fill their boats in passing) to empty a bottle or two of 

 oil into the sea, which will suppress the breakers, and allow them to pass safely. 



In various parts of the coast of the Mediterranean, and elsewhere, it is a 

 practice of the fishermen, to sprinkle a little oil upon the water, which smooths 

 the surface of the water that is ruffled by the wind, and thus enables them to se 

 and to strike the fish. 



