1822.] Philosophical Transactions for 1821, Part II. 147 



catch in its whale-bone net the shrimps that live in that situa- 

 tion is surrounded by blubber not unhke a cork jacket. 



** The enormous spermaceti whale, whose prey is not so far 

 removed from the surface, has the mass of spermaceti in a bony 

 concavity upon the skull. 



" The shark tribe have the liver loaded with oil, placed in 

 nearly the same situation as the lungs of the dugong. 



*^ As there are no vegetables (I believe) growing at the bottom 

 of the sea in very deep water, the nice adjustment of the body 

 of the dugong is confined to the shallows in the creeks near the 

 land." 



Upon comparing the bones of the two-horned rhinoceros with 

 those of the single-horned species. Sir Everard observes, that 

 there is no difference deserving of particular remark, except that 

 in the two-horned, the projection towards the front of the skull 

 formed by the union of the nasal bones, is more nearly in a 

 straight line, and more extended. This peculiarity, he thinks, 

 may be required to give sufficient surface for two horns. 



The tapir of Sumatra, as well as that of America, are stated 

 to have a greater general resemblance to the rhinoceros than to 

 any other animal. 



This paper is accompanied by five plates ; and an account of 

 the viscera of these animals is also given ; for which we refer to 

 the original paper. 



XIX. On the Mean Density of the Earth. By Dr. Charles 

 Hutton, FRS. 



It appears from this paper that in two instances only the mean 

 density of the earth has been certainly or approximately deter- 

 mined by experiment. 



" The former of these experiments," Dr. Hutton says, '^ was 

 made by Dr. Maskelyne, in the years 1774, 1775, and 1776, by 

 means of that large mountain^ in Scotland, in measuring its 

 dimensions, and in comparing its attraction on a plummet with 

 that of the whole earth on the same ; the calculations on it hav- 

 ing been made by myself, and first published in the Philosophical 

 Transactions of the year 1778 ; and since more correctly in the 

 second volume of my Mathematical Tracts. The other experi- 

 ment, by Mr. Cavendish, was by observing the attraction on 

 small pendulous balls, of two inches diameter, by larger ones of 

 ten inches diameter, as compared with the attraction of the 

 earth on the same. 



" By some strange mistake, or perversion, for many years, it 

 was customary among certain persons, to withhold the mention 

 of my name with regard to the great share that I had in the expe- 

 riment on Schehallien. But from certain complaints which I 

 have made, some Httle justice has lately been awarded to me on 

 that head ; though still, it w ould seem with reluctance, as the 



* Schehallian. 



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