﻿38-1 Royal Society : — Prof. Tyndall on the Blue Colour 



Mitchell, and the other old vaporists, were they to rise now amongst 

 their successors and take part in discussions on the earthquake 

 question. 



The author offers a new formula for calculating the temperature 

 of high- pressure steam, and some carefully worked-out tables of tem- 

 peratures and pressures of high-pressure steam, and says (in his 

 Prospectus), '.' it has been ascertained that, within known limits at 

 least, the force of saturated steam increases as the 4| -power of the 

 temperature, this being an enormously rapid ratio of increase. For 

 example, the 4^-power of the number 10 is equal to 31,622 and 

 a fraction. In this way we may understand how melted lava, which 

 has a temperature of about 3000° Fahr., may, when water gains 

 access to it, produce steam sufficiently powerful to account for the 

 greatest effects of earthquakes and volcanoes." Mr. Peacock's 

 studies on the properties of steam are useful adjuncts to the extensive 

 researches of Davy, Daubeny, Scrope, Daubree, and others on the 

 part played by water in the reaction of the interior of the earth 

 against its crust ; but when, led into those subterranean regions of hy- 

 pothesis where cavities or no cavities, solid nucleus or no nucleus, hot 

 centre or cool centre, are the vexed and vexing questions of the scien- 

 tific physicist, mathematical amateur, and general newspaper-reader, 

 he gives the usual compilation of facts and fancies, we can only hope 

 that some at least of his observations will be of use to somebody — 

 that he will enlarge his reading in the modern literature of the 

 subject — not mix up the little superficial caverns of limestone, lava, 

 and such like with the larger cavities in the earth's crust, for the 

 existence of which he judiciously argues — and, lastly, that he will 

 take into consideration the conditions and effects of Dana's theory of 

 the horizontal crumpling of mountain-masses and other strata by 

 lateral crush or contraction, before he allows everything to be ab- 

 sorbed by hypothetic cavities. 



LVI. Proceedings of Learned Societies. 



ROYAL SOCIETY. 

 [Continued from p. 308.] 

 Jan. 14, 1869. — Lieut.-General Sabine, President, in the Chair. 

 nPHE following communication was read : — 



- 1 - " On the Blue Colour of the Sky, the Polarization of Skylight, 

 and on the Polarization of Light by Cloudy matter generally." By 

 John Tyndall, LL.D., F.R.S. 



Since the communication of my brief abstract " On a new Series 

 of Chemical Reactions produced by Light," the experiments upon 

 this subject have been continued, and the number of the substances 

 thus acted on considerably augmented. New relations have also been 

 established between mixed vapours when subjected to the action of 

 light. 



I now beg to draw the attention of the Royal Society to two 



