Notices respecting New Boohs. 

 Extra Dense Flint Glass. Density 3-88947. 



389 



Ray. 



Observed. 



Calculated. 



Difference. 



S' 



1-688590 

 1-677020 

 1-664246 

 1-657631 

 1-650374 

 1-644871 

 1-642894 

 1-639143 



1-688581 

 1-677186 

 1-664237 

 1-657571 

 1-650319 

 1-644865 

 1-642927 

 1-639135 



•000009 

 •000166 

 •000009 

 •000060 

 •000055 

 •000006 

 •000033 

 •000008 



F 



E 



Di 



C 



B 



A 





Double Extra Dense Flint Glass. Density 4'42162. 



Ray. 



Observed. 



Calculated. 



Difference. 



G 



1-743210 

 1-727257 

 1-719081 

 1-710224 

 1-703485 

 1-701080 

 1-696531 



1-743210 



1-727280 

 1-719080 

 1-710166 

 1-703485 

 1-701144 

 1-696530 



•000000 

 •000023 

 •000001 

 •000058 



•oooooo 



•000064 

 •000001 



F 



E 



T) 1 



C 



B 



A 



; 



Such is all the evidence that can at present be offered on 

 behalf of the formula, but if further corroborative evidence 

 should be forthcoming, and the constants properly correlated, 

 chemists would find placed in their hands an instrument of 

 prodigious power for the purpose of exploring the molecular 

 constitution of bodies. 



If any should think it presumptuous to attempt to succeed, 

 where such eminent mathematicians as Cauchy 7 Redten- 

 bacher, and Briot have failed, it ought to be borne in mind 

 that, before the admirable researches of Professor Langley, 

 success was almost impossible. 



XLII. Notices respecting New Books. 



Geology : Chemical, Physical, and Stratigraphical. By Joseph 



Pbestwich, 31. A., F.B.S., F.G.S., &c. Vol. I. 1886 ; 477 pages, 



6 maps and plates, 218 woodcuts. Vol. II. 1888 ; 606 pages, 



2 maps, 18 plates of fossils, 256 woodcuts. 8vo. Clarendon 



Press, Oxford. 



^HE object and character of this work may be regarded as, first, 



-■- aiming at a widely philosophical and yet minutely scientific 



exposition of the action of natural laws in Chemistry, Physics, and 



Biology, on and within the Earth ; and, second, presenting especially 



