to calm the IVnvcs of the Sea. 229 



to the fca-nettle, a kind of vegetable fea-worms from oily 

 fubftaiices, which are thrown together in the hold of the 

 fliips, and the oil that oozes through between the Haves of 

 the caflcs, which, of courfe, is pumped out with the bilge 

 water. Seamen have alfo obfcrved, that the motion of a iliip, 

 the bottom of which has been newly payed, occafions much 

 lefs agitation in the water than that of another which has 

 not been daubed over with tar for a long time. Such in- 

 stances, of which feveral more equally decilive might be pro- 

 duced, are fufficicnt to authorife this ufe of oil, in oppufitiori 

 to thofe who pretend that it can be employed only in ponds 

 and other pieces of water of fmall circumference, where, by 

 diffufing itfelf over a mafs of water not much fwelled up, it 

 can eafily produce a tranquil furface. 



Thefe facSls feem to have been unknown to Dr. Franklfn 

 imtil he had an opportunity of making fimilar obfervations 

 himfelf. On his pafl'age from England to America fonie 

 pcrfon told him that he had thrown into a lake a veflel con- 

 taining oil in which flies had been drowned ; that the flies, 

 ^^■hich were apparently dead, began in an inftant to move, 

 and went round with a circular motion on the furface of 

 the water. Pr. Franklin afcribed this movement to a re- 

 pulfive power maintained by the oi], which gradually IflTued 

 from the fpongy bodies of the flies. In the year 1757, bein«- 

 at fea in the middle of a fleet confifling of ninety (hips def- 

 tined for Louifburg, he obfcr/ed that the movement of the 

 water was in one part of the fleet calm and uniform, while 

 the water between the other fliips was thrown into great ao-i- 

 tation by the wiyd. As he could not at that time dilcover 

 the caufe of this phenomenon, he aflccd the captain of one 

 of the fliips, who replied, that the cook had, no doubt, 

 thrown out the greafy water, which mud have rendered the 

 fides of the fliip oily. 



Franklin now paid more particular attention to this cir- 



tqntltancej and as he found that a drop of oil diflufed itfelf 



Q 3 fpecdily 



