Notices respecting New Books. 445 



is not so clear. In conclusion it may be asked, therefore, 

 what real reason is there why this hypothesis of action at a 

 distance should not be admitted. To some minds it seems to 

 present itself in the light of a theory which it is a priori diffi- 

 cult, if not impossible, to believe. But Physics has nothing to 

 do with mental impressions ; and in the history of the Induc- 

 tive Sciences there are many well-known instances, where 

 a priori notions of this kind have seriously hindered the ad- 

 vance of knowledge. It is evident that the progress of science 

 in any direction must be towards certain universal and final 

 facts, beyond which she cannot go. On the one theory, the 

 ultimate fact in the case of gravity is enunciated in a very 

 simple law of force, connecting together all ponderable bodies. 

 On the other theory, the ultimate facts are apparently enun- 

 ciated in the laws of impact between elastic bodies (which also 

 involve the conception of force), and in the statement of the 

 fundamental conceptions and results of the Kinetic Theory of 

 Gases, assumed to hold for an exceedingly rare gas pervading 

 all space. The writer submits that, a priori, one of these 

 theories is as likely as the other — but that both must be judged 

 by the test of their accordance with known facts, and by that 

 test alone must be accepted or condemned. 



On the general comparison of the two views, as to their 

 power of explaining facts, one remark may perhaps be allowed. 

 It will not, probably, be denied that, if we only knew the exact 

 laws of any action whatever between bodies, we could at once 

 explain it on the hypothesis that these bodies are made up of 

 centres of force, each possessing position and inertia, and act- 

 ing on the other centres according to laws which it would be 

 easy, or at least possible, to determine. It certainly cannot 

 be said at present that we could equally explain any action by 

 the mere laws of impact, even if we include in them those of 

 elasticity. So long as these two statements hold, it seems more 

 in accordance with the cautious spirit of true science to maintain 

 the old theory, than unreservedly to adopt the new one. 



LIII. Notices respecting Neio Books. 



Reports on the Geology of Queensland. By Bobert L. Jack, 

 F.G.S. Sfc. With Woodcuts. Plates, and Maps. 4to. Brisbane 

 1879. 

 r PHESE official Beports, three in number, presented to The 

 -*■ Honourable the Minister for Mines, Brisbane, by the Geo- 

 logical Surveyor for Northern Queensland, are of considerable 

 interest, especially as regards the occurrence and supply of Coal 

 and Gold in some parts of that region. The first is a Beport on 

 the Geology and Mineral Besources of the district between the 



