Influence of Oil on Water. 179 



be as well assured of the stability of our system, with respect to the 

 motion of rotation of its several members, as we are already respect- 

 ing their motion of translation. 



In a postscript, referring to a third cause of disturbance in the 

 place of the earth's axis of rotation, suggested in a letter from Sir 

 John Lubbock, namely, the effects of local elevation and depressions 

 at the earth's surface, the author states — If, with Humboldt, we re- 

 gard the numbers expressing the mean heights of the several conti- 

 nents, as indicators of the plutonic forces by which they have been 

 upheaved, we shall readily see that these forces are of an inferior 

 order to those affecting the general forms and structure of the earth. 

 If the second class of forces acted, so as not to influence in any way 

 the stability of the earth's axis of rotation, the former class might, 

 under certain conditions, produce a sensible change in the position 

 of the axis. But when the tendency of the second class of forces is 

 to increase the stability of the earth's axis, it would not be easy to 

 shew the possibility of such conditions, as to render the operation of 

 the other forces not only effective in counteracting that tendency, 

 but also capable of producing a sensible change in the place of the 

 axis of rotation. — (Proceedings of the Royal Society, Feb. 1852.) 



2. Influence of Oil on Water. — Professor Horsford, at the Al- 

 bany meeting of the American Association, read a paper, entitled, 

 " On the occurrence of Placid Water, in the midst of large areas, 

 where Waves were constantly breaking." 



The Professor said he had noticed frequently that there were 

 spaces of some extent, in places where the waves broke, which were 

 very smooth ; that though the swell, or rise and fall of the water, 

 was just as great, yet there was no breaking of the waves, no white 

 crest or comb, but he believed that these smooth spots were occa- 

 sioned by oil, or oleaginous matter, which had accidentally happened 

 to be spread on the surface at such places. To test this, he had, 

 himself, when there was quite a stiff breeze, with waves on the sur- 

 face of the water, which broke with considerable force off a comb or 

 crest, emptied a phial of oil on the water from a boat. The effect 

 was instantly seen. As far as the oil spread, the water was smooth, 

 and the waves did not break ; and what was very curious, the oil 

 spread over the surface almost as rapidly to windward as it did to 

 leeward. He had, therefore, inclined to the conclusion, that the 

 smooth spaces, which might be observed in the midst of places where 

 waves broke, were owing to the presence of oil, which might either 

 come from decaying fish, or some other substance from which oil 

 exuded. 



Commodore Wilkes confirmed the statement and observations 

 made by Professor Horsford. He cited the instance where he had 

 seen the same effects in a violent storm off the Cape of Good Hope, 

 from the leakage of a whale ship. He stated it was very curious 



