SCIENCE 



[N. S. Vol. XXIX. No. 731 



obtained by this means, and in making this 

 calculation we give every possible advantage to 

 the theory. Let us assume vfith Dr. Becke/ 

 that at the time of consolidation the surface 

 of the earth was at a temperature of 1300° C, 

 and increased at a uniform rate at least to a 

 depth of 0.02 of the radius or 126 kilometers, 

 and that up to the present time no appreciable 

 change of temperature has taken place beyond 

 that depth. Let us further assume that the 

 surface has been reduced to 0° and that the 

 present temperature gradient is a straight line 

 from the surface to a depth of 126 kilometers. 

 The average loss of temperature within this 

 shell is 1300/2 or 650°, and if we take the 

 specific heat per cu. cm. as 0.5 calories, the 

 total heat which has been lost per sq. cm. of 

 surface is 12,600,000X650X0.5 = 4.1X10° 

 calories. This is a very liberal allowance. 



Assuming an ocean 5 kilometers deep cover- 

 ing the whole earth, whose original tempera- 

 ture was 40° C. and which has cooled to 0°, the 

 total heat given out per sq. cm. of surface 

 would be (specific heat per cu. cm. ^1), 

 500,000 X 40 == 2 X 10' calories. This is only 

 one half of 1 per cent, of the heat furnished 

 by the land and may therefore be neglected. 



The heat at present being received from the 

 sun equals 2 calories per sq. cm. per minute, 

 measured at right angles to the sun's rays.' 

 As this falls on the section of the earth it 

 must be divided by 4 to give the average 

 amount on the earth's surface. Let us sup- 

 pose, further, that three fifths of the remainder 

 is lost by reflection and other causes and does 

 not heat the earth's surface. This leaves 0.2 

 calorie for the average amount received by 

 1 sq. cm. of the earth's surface per minute; 

 and in one year the total amount received 

 would be 0.2X60X24X365 = 10° calories, 

 and as the earth has a practically stationary 

 temperature it is losing this much heat per 

 year by radiation into space. At this rate all 

 the heat lost from the earth since consolida- 

 tion could only keep up the present average 

 temperature for a number of years equal to 

 4.1 X lOyiO' = 41,000 years ; but if on account 

 of the cloud-blanket only 10 per cent, as much 



"Science, February 7, 190S. 



"Science, April 24, 1908, p. 663. 



heat is necessary to maintain the temperature 

 it would last 410,000 years; if only 1 per cent. 

 were needed, it would last 4,100,000 years, a 

 period much shorter than pre-Mesozoic time. 



But what would establish and maintain a 

 blanket of clouds around the earth, and espe- 

 cially over great inland regions like the centers 

 of Africa and Asia? The only places where 

 clouds are now prevalent are places in high 

 latitudes where moisture is continually pre- 

 cipitated from the winds which blow pretty 

 steadily from warm seas; but even with our 

 present atmospheric circulation the interior of 

 the great continents are rather dry. With the 

 uniform temperature which Mr. Manson predi- 

 cates in Paleozoic time there would be no 

 winds, and the sun would soon break up the 

 cloud-covering over the interior of the con- 

 tinents, as there would be no steady supply of 

 moisture. Moreover, an atmosphere heated at 

 the bottom is in unstable equilibrium, and con- 

 vection currents would be set up which would 

 carry the moist air to high altitudes and re- 

 sult in heavy downpours of rain and a clear- 

 ing of the atmosphere; for the available heat 

 would be entirely inadequate to supply mois- 

 ture to form clouds as fast as it would be pre- 

 cipitated as rain. The existence of clouds 

 would have no influence on the convection cur- 

 rents. Mr. Manson mentions these currents, 

 but does not attach any great importance to 

 them. 



It is to be noted that geologists who have 

 given attention to the earlier glacial periods do 

 not consider that they were due merely to 

 small glaciers at high altitudes, but that they 

 represented real, even if not very extensive, 

 changes in climate. Moreover, Professor J. 

 W. Gregory firmly maintains that throughout 

 g- ological times we have had a zonal distribu- 

 tion of temperature very similar to that of the 

 present day.* It is therefore, quite possible 

 that the continued uniform climate which Mr. 

 Manson's theory was developed to explain, did 

 not really exist. 



Professor Schaeberle" approves Mr. Man- 

 son's theory and states that " The inherent 



* " Climatic Variations," Proc. Tenth Intern. 

 Geol. Cong. Mexico, 1906, Vol. I., pp. 407-26. 



= Science, March 6, 1908, p. 392. 



