449 



tube ; and when water has been admitted into the other, it is boiled 

 over a lamp till all the air is expelled ; and while the stream is still 

 issuing with violence through the capillary extremity, the end of it 

 is held in the flame of the lamp, till in proportion as the force of the 

 steam diminishes, the heat acquires power to seal the tube hermeti- 

 cally. 



When such an instrument has been successfully exhausted, if the 

 empty ball be placed in a freezing mixture of salt and snow, the 

 water contained in the opposite ball will be frozen solid in a very few 

 minutes. 



The first vapour being condensed by the common effect of cold, is 

 immediately succeeded by a fresh emission, with proportional reduc- 

 tion of temperature ; so that heat is continually withdrawn, or cold 

 generated at a distance by the freezing cause. 



A Catalogue of North Polar Distances of some of the principal fixed 

 Stars. By John Pond, Esq. Astronomer Royal, F.R.S. Read De- 

 cember 17, 1812. [Phil. Trans. 1813,^. 75.] 



A Description of the solvent Glands and Gizzards of the Ardea Argala, 

 the Casuarius Emu, and the long-legged Cassowary from New South 

 Wales. By Sir Everard Home, Bart. F.R.S. Read December 17, 

 1812. [Phil. Trans. 1813,^. 77.] 



In the first of these birds the solvent glands are different from those 

 of any other bird examined by the author, each gland being made up 

 of five or six cells, that open into one common excretory duct ; but 

 its gizzard is very similar to that of the crow. 



In the Emu the solvent glands are oval bags, one fourth of an inch 

 in length, and one sixteenth wide. The gizzard differs from that of 

 the crow in having a thicker lining, and is remarkable solely for its 

 situation ; for it is not placed, as usual, between the stomach and 

 the duodenum, but forms a pouch on one side, so that food can pass 

 onwards direct into the duodenum, without being received into the 

 gizzard. 



In the Cassowary of New South Wales, the solvent glands are si- 

 milar to those of the emu, but larger ; and the gizzard is also similar 

 in every respect, but stronger. 



The author further remarks upon the circumstances in the struc- 

 ture of the cassowaries, and other birds most nearly allied to them, 

 which adapt them to the different degrees of fertility of the countries 

 they inhabit. 



The Emu of Java, where there is abundance of food, has intestines 

 that are of large diameter, and comparatively short, so as to afford 

 free passage to the superfluity of food they take, and a gizzard to be 

 employed only occasionally. 



The Cassowary of New South Wales has intestines of smaller dia- 

 meter, thirteen feet long ; and a stronger gizzard, more frequently 

 employed in a less productive country. 

 2 G 



