212 On the Properties of Water 



Association in 1862. From the 

 a parallel passage : — 



Mr. Croll (1867). 



". It is in the equatorial regions 

 that the earth loses as well as 

 gains the greater part of its heat. 

 So of all places it is here that we 

 ought to place the substance best 

 adapted for preventing the dissi- 

 pation of the earth's heat into 

 space, if we wish to raise the ge- 

 neral temperature of the earth " ■ 

 (p. 130). 



Again : — 



Mr. Croll (1867). 

 " Water, of all substances in 

 nature, seems to possess this 

 quality to the greatest extent ; 

 and, besides, it is a fluid, and 

 therefore adapted by means of 

 currents to carry the heat which 

 it receives from the sun to every 

 corner of the globe" (p. 130). 



in relation to Terrestrial Climate. 

 abstract of the latter I may give 



Professor Hennessy (1862). 



" The torrid zone of the earth 

 must be far more effective than 

 all the rest of the earth's surface 

 as a recipient of heat. It follows, 

 therefore, that the distribution of 

 the absorbing and radiating sur- 

 faces within the torrid zone must 

 upon the whole exercise a pre- 

 dominating influence in modify- 

 ing general terrestrial climate " 

 (Report of the British Associa- 

 tion, 1862, Transactions of the 

 Sections, pp. 31, 32). 



Professor Hennessy (1859). 



"The physical properties of 

 water appear upon the whole 

 more favourable than those of 

 the land, to the accumulation, re- 

 tention, and distribution of solar 

 heat throughout the matter com- 

 posing the external coating of 

 the earth" (p. 192). 



Another conclusion which I drew from this, namely that a 

 state of high mean temperature over the earth, such as seems to 

 have existed during some geological epochs, would be brought 

 about by the absence of continents or large islands and the pre- 

 valence of oceans, Mr. Croll in a former paper (Phil. Mag. 

 August 1864, p. 128) attributes to Professor Phillips, although 

 Professor Phillips himself in a note cites my publication where 

 the conclusion was first enunciated. In the same paper (p. 123) 

 Mr. Croll refers to the Astronomer Royal and " others" as hav- 

 ing proved in 1860 the inadequacy of geological causes to dis- 

 turb the earth's axis of rotation. Having written to the ' Athe- 

 naeum' at the same time as the Astronomer Royal in 1860, it 

 is possible that I am meant among the " others." The prin- 

 cipal object of my letter was to call attention to the fact that my 

 proof of the stability of the earth's axis, contained in a letter 

 addressed to the late Sir John Lubbock, was published eight 

 years before, in the Proceedings of the Royal Society (see also 

 Phil. Mag. May 1852, S. 4. vol. iii. p. 386). 



In his paper of August 1864, Mr. Croll criticises Poisson's 



