New Improvements on Steam-En glne%. 123 



the temperatures of animals; where these organs are ex- 

 tensive, the respirations arc performed at regular intervals, 

 and are not governed by the will, the whole mass of blood 

 being exposed to the atmosphere in each circulation, in all 

 such animals lining without the tropics, their temperature 

 ranges above the ordinary heat of the atmosphere, their 

 blood contains more of the red particles than in ihe other 

 classes, and their muscular irritability ceases more rapidly 

 after violent death. 



The respirations of the animals denominated cold-blooded 

 are effected differently from those of high temperature; in 

 some of them, as the amphibia of Linnceus, the lungs re- 

 ceive atmospheric air, which is arbitrarily retained in large 

 cells, and not aliernatclv and frequently changed. The 

 fishes, and the testaceous vernies, have lungs which expose 

 their blood to water; bat whether the water alone, or the 

 atmospheric air mingled with it, furnish the changes in the 

 pulmonary blood, is not known. 



In most of the genera of insects the lungs are arborescent 

 tubes containing air, which, by these channels, is carried 

 to every vascular part of the body. Some of the vermes of 

 the simpler construction have n.o appearance of distinct or- 

 gans; but the respiratory influence is nevertheless essential 

 to their existence, and it seems lo be effected on the surface 

 of the whole body. 



In all the colder animals the blood contains a smaller 

 proportion of the red colouring particles than in the mam- 

 Bialia and aves : the red blood is limited to certain portions 

 of the body^ and many animals have none cl the red par- 

 ticles. 



> [To be continued.] 



XXV. Account o/" il/r. Arthur WooL?'s nciv Improve- 

 ments on Steam- Engines. 



In our nineteenth volume, p. 133, we gave a short account 

 of a former improvement made bv Mr. Wooif on the steam- 

 engine, founded on a discovery that steam, of anv higher 

 teniperature than that of boiling water, if allowed to pass 

 into another vessel kept at the same temperature as the 

 steam itself, will expand to as many times its volume, and 

 still be equal to the pressure of the common atmosphere, as 

 the number of pounds which such steam, before being al- 

 lowed to expand, could maintain on each square inch of a. 



safety- 



