526 Proceedings. 
Mr. Kirk agreed with Dr. Hector regarding the difficulty in understanding how such 
plants as Magnolia and the tulip tree could not only exist but perfect their flowers and 
fruit where light was absent for six months of the year. The absence also of all forms of 
low plant-life, which might naturally be expected under such circumstances, required 
explanation. 
Mr. Cox thought the author had overlooked the evidence of former glacial periods at 
successive intervals as far back as the Devonian epoch, with intervening periods, during 
ich warmer conditions prevailed. 
Marti apman said that, unless the oldest formations were proved to be 
sedimentary, the presence of water in them would prove nothing, as water must infiltrate 
the deepest rock we can reach. He thought the temperature at which plant-life could 
exist had been understated, from his having collected organisms in the hot springs in 
Hecla (Iceland), which had a very high temperature. 
Mr. Carruthers thought that the paper was so important that its discussion should 
have been deferred. He thought it not yet proved that there was a central heat, and 
certainly not that it could influence climate. The argument derived from increase of 
temperature with depth in the earth's crust only proved a modified form of volcanic 
action—in some places greater than in others. The greatest depths to which we reached 
were the bottoms of the oceans, and there we found no evidence of a higher temperature, 
but the reverse. In open oceans it might be argued that this was due to the removal of 
the heat by currents ; but in the case of the Mediterranean, and also in Loch Ness, which 
are deep holes without an outlet, excepting for the surface water, the temperature at the 
bottom is the same as the average winter temperature of the air at the surface. In the 
nebular theory heat had always been assumed as being the expanding force which was 
gradually lost; but this was not proved. Cosmical dust is not kept apart by heat, but by 
ihe continuous motion of the particles. He thought the balance of evidence was against 
the theory of central heat. If the earth had once been hotter it would have become 
smaller in cooling, and its velocity of rotation would have increased; but this was 
contrary to fact, as the rotation had been retarded by about three hours since exact 
observations were first made. With regard to what had been said about the thickness 
o arth’s crust, the existence of tides proved that it must be so great as to be 
sala rigid. He considered it quite possible for plants to live in darkness if they 
mained dormant, like geraniums which are placed in a dark cellar during the winter. 
Mr. Travers, in reply, said he had not advanced any theory of his own, but merely 
wished to direct attention to views that were gaining ground. He thought that when 
geologists had studied the works to which he had referred, they would very much alter 
their present opinions on the subject 
Owing to the late hour at sid. the discussion terminated, several papers were held 
over for next meeting. 
Fourta Meerine. lst September, 1877. 
W. T. L. Travers, M.H.R., F.L.S., President, in the chair. 
New Members.—A. T. Maginnity, J. J. Cherrett. 
Attention was drawn to several additions to the library, viz., publications on the 
geolozieal survey of the United States and othcr works received through the Smithsonian 
