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Particulars respecting the Anatomy of the Dugong, intended as a Sup- 

 plement to Sir T. S. Raffles's Account of that Animal. By Sir 

 Everard Home, Bart. F.R.S. Read June 29, 1820. [Phil. Trans. 

 1820, p. 315.] 



The object of this communication is to complete the anatomical 

 description of the Dugong, already presented to the Society by Sir 

 Thomas Stamford Raffles, who has sent the author a young female 

 animal entire, together with the viscera and skeleton of a male. 

 Drawings representing the external form of the animal, and of its 

 several parts, are annexed. Sir Everard particularly describes the 

 peculiar structure of the stomach of this animal, which differs from 

 all others, and is so complex that description is scarcely intelligible 

 without the aid of a drawing. In some respects it resembles that of 

 the whale, the peccari, hippopotamus, and beaver ; at least it con- 

 tains parts met with in the stomach of those tribes, but the parts are 

 differently situated. 



On the Compressibility of Water. By Jacob Perkins, Esq. Commu- 

 nicated by the late Right Hon. Sir Joseph Banks, Bart. G.C.B. 

 P.R.S. Read June 29, 1820. [Phil Trans. 1820,^. 324.] 



A hollow and water-tight cylinder, 3 inches in diameter and 1 8 

 inches long, with a rod five sixteenths of an inch diameter, sliding 

 through a stuffing box at one of its extremities, and having upon it a 

 flexible ring, placed just above the stuffing box, was filled with water, 

 and put into a cannon of sufficient dimensions, fixed vertically in the 

 earth, with its touch-hole plugged, and its muzzle about 18 inches 

 above ground. A strong cap was firmly secured upon the mouth of 

 the cannon, with a small forcing pump tightly screwed into its centre. 

 There Avas an aperture secured by a valve, one pound pressure upon 

 which indicated an atmosphere. Upon forcing water into the cannon, 

 it was found that when the instrument contained within it, called by 

 the author a Piezometer, had suffered a pressure equal to a hundred 

 atmospheres, the position of the ring upon the piston indicated that 

 it had been forced into the cylinder to a depth of eight inches, show- 

 ing that the water had suffered a compression of about 1 per cent. ; 

 the same effect was produced by sinking the piezometer to a depth 

 of 500 fathoms in the ocean. Upon sinking a strong empty bottle, 

 well corked and tied down, to a depth of 300 fathoms, the neck 

 only was found remaining upon the line ; from the appearance of 

 which it was evident, that a quantity of water, sufficient to fill the 

 bottle, had at that depth been forced through the cork and its co- 

 verings, and that the water expanding during the drawing up of the 

 bottle had broken it. 



It appearing to the author that the original indication of the pie- 

 zometer was rendered erroneous by the collapsing of the leather upon 

 the rod under such great pressure, he employed a modification of the 

 instrument, in \vhidi a valve was used as a substitute for the piston, 



