If so, this effect will be greatly magnified during a period of high eccentricity, such as the earth has certainly passed through in the past. We will state first, that the more elliptical the orbit becomes, the longer Summer we have, and the shorter Winter. Astronomically, Spring begins the 20th of March, and Fall the 22d of September. By counting the days between the epochs it will be found that the Spring and Summer part of the year is seven days longer than the Fall and Winter part. But if the earth’s orbit becomes as highly eccentrical as in the past, this difference would be thirty-six days.15 This would give us a long Spring and Summer, but a short Fall and Winter. This in itself would make a great difference. We must beer in mind, however, that at such a time as we are here considering, the earth would be ten millions of miles nearer the sun in Winter than at present. It would certainly then receive more heat in a given time during Winter than at present.16 Mr. Croll estimates that whereas the difference in heat received during a given time is now one-fifteenth,17 at the time we are considering it would be one-fifth. Hence we see that at such a time the Winter would not only be much shorter than now, but at the same time would be much milder. These are not all the results that would follow an increase of eccentricity. The climate of Europe and North America is largely modified by those great ocean currents—the Gulf Stream and the Japan current. Owing to causes we will not here consider, these currents would be greatly increased at such a time. As a result of these combined causes, Mr. Croll estimates that during a period of high eccentricity the difference between Winter and Summer in the Northern Hemisphere would be practically obliterate. The Winter would not only be short, but very mild, and but little snow would form, while the sun of the long Summers, though not shining as intense as at present, would not have to melt off a great layer of snow and ice, but the ground became quickly heated, and so warmed the air. Hence, if Mr. Croll be correct, a period of high eccentricity would certainly produce a climate in the Northern Hemisphere such as characterized many of the mild interglacial epochs as long as the earth passed its perihelion point in Winter.