9^9 



Price.] -■> i -> [March 3, 17, & 



is to be shown, not conjectured, not invented. We are not to be per- 

 mitted to explain a didiculty by an imagined cause that involves tenfold 

 greater diHiciiltios. This they seeni to do who make the induction of a 

 continental i)olar ice-sheet, such as the glacialists describe it, with the 

 vividness of those who might have seen it. Though their subject be glacial 

 they write with a fervor that betrays an enkindled imagination. 



James Croll emphatically invokes an astronomical cause for the Glacial 

 Epochs; but the astronomers have expressed adverse opinions. Ilinuboldt. (4 

 Cosmos 460) thus quotes Poisson on the Stability of the Planetary system: 

 " It follows from the theorem of Lambert, that the quantity of heat which 

 is conveyed by the Sun to the Earth is the same during the passage from the 

 vernal to the autumnal equinox as in returning from the latter to the 

 former: The much longer time which the Sun takes in the first part of 

 its course, is exactlj'- compensated by its proportionately greater distance, 

 and the quantities of heat w'hich it convcN^s to the Earth are the same while 

 in the one hemisi)herc or the other, north or south." Humboldt also 

 quotes Arago on Excentricitj^: "As the excentricity always has been, and 

 always will be, very small, the influence of the secular variations of the 

 (piantity of solar heat received by the Earth upon the mean temj^erature 

 Avould appear also to be very limited." If these opinions be true we must 

 look to earthly causes; and not to the Earth's orbital excentricity produced 

 by conjunction of planets in the heavens, or variable heats from the Sun. 



There is, however, one cause besides the elevation of the mountains, 

 and the inter-continental influx of the Arctic Sea, wherebj^ the temperature 

 of Northwestern Europe, may at sometime, have been greatly reduced, and 

 that without any cause at variance with the normal physical laws. We 

 have shewn many proofs wiiy there was a central ocean between the widely 

 spreading systems of mountains of the Eastern and Western parts of North 

 America. It may hence have been that the waters heaped up by the 

 Earth's rotary motion, and the trade winds into the Gulf of Mexico, found 

 a passage through that inter-continental sea; and were not, as noM% com- 

 pelled to find their exit by Cape Florida and the Atlantic Ocean, to reach 

 and warm AVestern Europe. Dr. Dawson did not suggest such a cause for 

 such effect; but said what would truly be the consequence of such cause 

 when he said, "any change that Avould allow the equatorial current to pur- 

 sue its course through to the Pacific, or along the great inland valley of 

 North America, would reduce the British seas to a boreal condition." 

 Dawson, 70. The fact shown, the induction is legitimate and inevitable; 

 and seems to be proved by established isothermal lines, shewing how greatly 

 the gulf-stream mitigates climate. 



•How then are we to account for a past period of glaciation, of whatever 

 intensity, greater than at the present time in certain places. We may do 

 it without invoking abnormal causes. An adequate cause exists within 

 less than five miles of every foot of the surface of the earth. Within that 

 limit, with land elevation to the height of the upper snow line, and breadth 

 to hold an adequate Mer de Olace, yet with a sufficient declivity to put the 



