Morning journal and courier., 1885-07-14
THE EARTH AND ITS CHANGES.
The Glacial Epoch and its Results When Ice Will Again Disappear.

A
 When Ice will Again Disappear. From La Nouvelle Revue.l
 During the whole period of the primary rocks and the formation of coal strata tropi- cal heat prevailed from latitude 35' to longi- tude s0o-to the polar regions, that is. The temperature was uniform over the whole earth. During the first half of the secon- diary period, that of jurassic rocks and chalk the climate remained the same; the same plants and the same animals are found all over the globe. During the second half of the period, however, the climate began to cool somewhat, and deciduous trees made their appearance, though tropical plants were still to be found in England and Denmark. Even to the middle of the tertiary period there was equality of climate in all attitudes; but the temperature in Europe fell very grad ually, and it is certain that at the end of the tertiary period there was no ice on the globe, not even at the poles or at the top of the highest mountain.
 With the quarternary period great change took place. The reindeer was to be found in all parts of Europe, the cold was excessive, and the great Swiss glaciers extended to the south of France. The glacial epoch was in full swing, and the uniformity of tempera- ture formerly prevailing had been destroyed. Then reflex action begins; the glaciers, and with them the reindeer and the mammoth, retreat as slowly as they advanced. At the furthest point of the glacial extension the cold became so intense that a of ice GOV cred half Russia, all Prussia, Hanover, Hol- land, and part of England.
 What, then, was the cause of this change from uniformity to excessive cold over so large portion of the earth's surface? And how is it that the extent of the cold region, after having reached it's maximum, gradually retreated? We attribute the change to the defection of the earths axis from the per pendicular, and then it's gradual return to- ward it's old position. In the case of per pendicular axis the climate will be nearly equable all over the globe; there will be some difference in different attitudes, owing to the fact that the suns rays are only vertical at the equator, but it will be comparatively small There would be nights long enough in any part of the planet to leave time for the formation of large quantity of ice. Consequently, all we have to do to ac- count for the ages of time when the climate, as geology tells US, was the same all over the world, is to imagine the earth with per pendicular axis in place of an axis at an an- glesswith the plane of the elliptic as it is now.
 The angle to-day is 23' 27 g. But the Chinese astronomer Choo Kung, who measur- ed the angle 1, 100 years before Christ, made it 230 54, and subsequent measurements made in B. C. $50, 25O and 50, and in A. D 461, egg, 1880, 1000, 1279, 1437, 1900 and 1850, by celebrated astronomers, Greek, Ch; nese, Arabian and Freuch, give the angie as follows at the respective dates-23' 49, 23 46', 230 41', 230 39', 23o 36', 23o 3A, 230 32', 230 31', 230 GO, 23' 27 ST, 230 27 33'. A succession of figures like these conveys little nearing to the unmathematical mind; but the meaning is clear, nevertheless. The ob- iquity of the axis has diminished steadily for the last 5, 1000 years, and the diminution amounts in all to 26 27', showing that it's tendency now is toward the perpendicular at the rate of 49' forty-eightmseconds) every 100 years. This means that the polar circle is being reduced at the rate of 1 ,3553 metres -or, roughly, ,466 yafds-every century, or 1415 ya1dsNevery year, the temperate zone being increased proportionstely. It will take the axis TIC, ,946 years to move at its present rate through the distance which now sepa- rates it from the perpendicular.
 As long as the axis remained perpendicu lar, the climate, as has been said, was uni formly hot, and in Greenland and Spitzber- gen pomegranates grew. One day the axis began to change. At first this had slight effect For ages the modification was tri- fling; even at the tertiary period there was still no ice, and snow. when it fell, soon dis appeared But by degrees the zones were traced. Round the pole the change was al ready complete, and the radiation of the earth overcame the solar heat, and the night 
 The quarternary period was entered; man ap- peared in our continent; the angle ot obliqui- ty of the axis being about 15, and the polar belt about 1 1000 miles in extent, finished at the southern part of Spitzbergen. The gla- cial epoch had begun. What then was the maximum of the inclination of the axis when our earth was divided into two belts of ex- treme cold (wehn glaciers covered the great CT part of Europe) and torrid heat? Not, less certainly, than thirty-f1 degrees-plob- ably nearer forty degrees. Taking, however, thirty five degrees, and assuming that the deviation of the axis proceeded at the same rate as it's return is going on now, then 262,- 900 years elapsed between the first move ment and the day when the axis began to re- turn. This check seems to have taken place at the end of the quarternary period, v hen the earth had assumed much about the same general condition that we see to-day. It necessarily required other thousands of years to effect a change of climate in the opposite direction. The alteration is clearly manifest ed in the geological strata by the immigration and emigration of the reindeer. There would have elapsed, then, since the axis began its backward movement until now-assuming 35 degrees to be the maximum of inclination -86, ,554 years, which, with the 176, 946 years that have still to be traversed ere the axis once more becomes perpendicular, would give 262, 800 years as the total period between the first movement and the moment of extreme inclination. Already the glacial period is considered as at an end in southern Seandi navia, and the Swiss glaciers are nothing to what they were. Nevertheless, 50,000 years must still elapse before glaciers disappear.
 As to the age of man upon the earth, as suming that he did not appear until the lower stages of the quarternary period in which his bones first are found, it is certain that the climate was much warmer in Europe then than it is now. On my calculations, man has been 223, 198 years on the earth, and 349 ,O54 years have passed since the axis of the earth first moved out of the perpendiou- lar. M. RAMUs. MEDICAL DEPARTMENT STATE UNIVERSITY {
 OF IOWA, IOWA CITY, IA.