4 SPECIAL RESULTS OF OBSEIIVATION IN THE DOMAIN 



tary system to the vegetable covering with which the earth 

 is invested, and to the minutest organisms often floating in 

 the air, which escape our unassisted vision. In order to 

 allow us to contemplate with greater clearness the existence 

 of a common bond comprehending the whole of the material 

 universe, the government of never changing laws, and the 

 causal connection of entire groups of phenomena so far as 

 is yet known to us, it was necessary to avoid the accumula- 

 tion of detached facts. Such care appeared more particu- 

 larly requisite where, in the telluric sphere of the Cosmos, 

 by the side of the dynamic actions of moving forces, we 

 find manifested the powerful influence of the specific hetero- 

 geneity of matter. In the sidereal or uranological part of 

 the Cosmos, the problems, in all that can be reached by 

 observation, are in their nature of admirable simplicity ; 

 being by the theory of motion susceptible of rigid calcula- 

 tion, according to the attracting force of matter and the 

 quantity of its mass. If, as I believe, we are justified in 

 regarding the aerolites, or meteoric asteroids, as parts of 

 our planetary system, they, but they only, by falling upon 

 our globe, enable us to recognise diversity of substance in 

 bodies belonging to cosmical space external to our own 

 planet. ( l ) We have here the reason why terrestrial phse- 

 nomena have hitherto been less generally, and less success- 

 fully, subjected to mathematical development and treatment, 

 than have the movements of the heavenly bodies, with their 

 mutual perturbations and periodical returns, governed, so 

 far as our perceptions extend, only by the one fundamental 

 force of homogeneous matter. 



My endeavours in the telluric portion of the description 

 of Nature were directed to the arrangement of the phseno- 



