These variatious and relations are now being made tlie subject of cartful 

 obBervations, and Dr. Tait remarks that in this one direction alone a field has 

 been opened up for inquiries which, even with our present appliances for obser- 

 vation, may well occupy the world for a generation to come. 



Professor Tait has made also some most interesting observations upon 

 Nebulae and Comets ; on the former of these bodies, he says that they have now 

 been proved to shine as glowing gas merely, and therefore in all probability they 

 are not much more distant than some of the nearest stars, and they may be, the 

 professor adds, "Vast systems of small cosmical masses in the act of groupmg 

 themselves by mutual gravitation, impact, and friction into a new star, the 

 incandescent gas being due to the impact and the friction." In them we may be 

 actually watching ths formation of a Solar System. These ideas seem to lend 

 countenance to La Places Nebular Hypothesis. 



With reference to comets, the professor says that there is good reason for 

 thinking that they are only showers of stones ; and in proof of this theory he 

 remarks that a shower of stones would behave very much like a comet in its 

 revolution round the sun ; and also that the orbits of the August and November 

 meteors have been found i.lentical with those two weU-known comets. 



The heads of the comets give spectra, like those of Nebuh-e, of incan- 

 " descent gases, but their taUs appear to shine by reflected solar light only. If 

 these views be true the meteoric displays would receive a fuU explauation, as 

 the earth would be in fact passing through the taU of a comet. 



Before leaving this subject it wiU, I know, give this Society gratification 

 to know that Dr. Balfour Stewart, who so kindly gave us a suggestive paper 

 on Meteorology, last year obtained the Rumford medal, one of the highest 

 scientific honours. It was awarded to him for the discovery of the law " that 

 the absorption of a particle of light or heat is proportional to its radiation, 

 which law holds for every variety of light or heat." 



Dr. Stewart has also been making investigations on the solar spots of his 

 enquiries leave no doubt that the sun is a variable star, and that the spots 

 depend on the position of the planets. 



But perhaps there are no more interesting speculations of modern science 

 than the views of some of our first naturalists concerning the origin of life and 

 the correlation of vital with other forces. 



Mr. Darwin's theory of the origin of species by natural selection is so well 

 known that it is quite unnecessary for me to dwell upon it, and in his most 

 interesting work upon Plants and Animals under Domestication he gives valuable 

 information on many subjects, and also brings forward the interesting theory 

 of Pangenesis. Referring physiological enquirers to the above work, I will pass 

 on to notice the theory of the origin of species brought forward by Professor 

 Owen in the concluding remarks of his great work on the Comparative Anatomy 

 and Physiology of Vertebrates. 



