7^ Astronomical Society : the Astronomer Royal 



chemical and physical ; whilst others can only be called into play 

 under conditions of a more complex nature, which are only supplied 

 by a living organized system, where many particles being combined 

 by a previously- existing life into one structure, exhibit actions of a 

 pecuhar character, dissimilar to any they have heretofore presented, 

 which are denominated vital. 



The dependence of life upon external stimuli is then pointed out, 

 and a great variety of interesting facts, many of them novel, are col- 

 lected, relative to the influence of heat, light, and electricity upon 

 living beings. The general laws which have been ascertained to 

 govern the structure and actions of organized beings are then enun- 

 ciated, and their application illustrated by examples. To pursue 

 their application through the whole range of the animal and vege- 

 table kingdoms is the object of the second book, entitled Special 

 Physiology. Here each function is considered in detail, in the va- 

 rious phases under which it appears in the ascending scale both 

 of the vegetable and animal kingdoms; the fundamental unity 

 which prevails throughout is displayed ; and the very extraordinary 

 correspondence which exists between the transitory states of dif- 

 ferent organs in the embryo condition of the higher classes of each 

 kingdom, and the permanent forms of the same in the lower, is de- 

 monstrated in a striking and satisfactory manner. This part of the 

 volume is illustrated by a large number of well-executed figures, 

 which greatly aid the comprehension of the text. 



The author appears to us to have fulfilled his design in the most 

 satisfactory manner ; and as his work has been received with high 

 approbation by the Medical Press, we can feel no hesitation in re- 

 commending it to our scientific readers as the one best calculated 

 to impart to them a sound knowledge of the principles of physio- 

 logy. We may add, that the clearness of its style, and the simple 

 manner in which the highest truths on this deeply-interesting sub- 

 ject are presented to the student, render it not only a useful, but an 

 agreeable book to any reader of ordinary intelligence. 



XII. Proceedings of Learned Societies. 



ROYAL ASTRONOMICAL SOCIETY. 



Nov. 8, 'T^HE following communications were read : — 

 1839. -■- On the Detei^mination of the Orbits of Comets, from 

 Observations. By G. B. Airy, Esq. Astronomer Royal. 



The author begins by remarking, that the generality given by 

 Laplace to the investigation of the orbits of comets is so complete, 

 and the variations on the method introduced by other writers so 

 numerous, that, as regards generality and facility, the subject may 

 probably be considered as exhausted. The method which is de- 

 veloped in the present Memoir professes to be merely a modifica- 

 tion of Laplace's method, directed by considerations of a purely 

 practical nature, which are known to the working astronomer ; but 



