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aware of the uncertainty attending any set of observations made 
by a single individual. 
Prof. CAYLEY suggested a diagram, similar to those given in 
meteorological reports, indicating, by a curved line and dots, 
the altitude of the Sun at different times: from which the 
meridian altitude and its time might be approximately inferred. 
The Secretary then read a paper 
On the Temperature of the Earth in times anterior to 
_ the Eocene period. By Mr Rours. 
Mr Roéurs stated that geological evidence seemed to point 
to a warm and equable climate over a great part of the earth in 
preeocene days. He thought it probable that this high tem- 
perature was due to the internal heat of the earth, and that the 
amount of heat radiated by the sun and received by the earth 
may have been less than it is now—the solar atmosphere ob- 
structing radiation more than at present, although the energy 
and mean temperature of the sun were greater in early times. 
He referred the first great glacial period to a time when the 
internal heat of the earth was diminishing, and the solar ra- 
diation had not reached its present amount. 
Mr Souas said that there was clear evidence of ice-action 
at various epochs long anterior to the Eocene period, so that 
Mr Rohrs’ theory of a long period of uninterrupted high tem- 
perature was geologically untenable. 
