498 DR MURRAY ON THE DEEP AND SHALLOW-WATER MARINE FAUNA 



a much greater absolute increase at the poles, the intervening latitudes receiving an 

 amount intermediate between these limits. Such a distribution of energy would tend 

 to that uniformity of climate apparently demanded by palseontological evidence. 



A few illustrative figures calculated under the above assumptions may be of interest ; 

 in this approximation the effects of solar and terrestrial atmospheres have been neglected. 

 The earth as a whole would receive from the large sun about 7 2 per cent, more energy 

 than at present. At the equinox the equator would receive 2 - 6 per cent, more energy 

 than it does at present; the polar circle 16*7 per cent. more. At the solstice the 

 equator would receive 3 per cent, more energy than at present ; lat. 45° at the summer 

 solstice would receive 4*1 per cent. more. When we consider the insolation at the pole 

 we find that during the whole year the pole would receive between 17 and 18 per cent, 

 more energy from the large sun than from the present small one. As much of this 

 fresh accession of energy would be spread over the period from the autumnal to the 

 vernal equinox, when, at present, the pole receives no heat from the sun, the ultimate 

 effect would be the raising of the temperature during the polar winter. 



It may be interesting here to state that when the centre of this large nebulous sun 

 rested over either of the tropics, part of the limb would be vertical 23° 28' polewards 

 from the tropics, that is at the 47th parallel ; an equatorial belt 94° wide, having an 

 area of 143,830,200 square miles, or 73*14 per cent, of the earth's surface, would, be 

 under the vertical rays of some portion of the sun's surface at least twice in the year. 

 The corresponding region of the earth (having vertical rays) at present has an area of 

 only 40 per cent, of the earth's surface, or about 79,258,000 square miles. 



At the summer solstice this large sun would shine over one pole to a distance of 

 47° on the other side of the pole, that is to say, any place within the 43rd parallel would 

 at the solstice enjoy a 24 hours day. But at the summer solstice a belt 4° in width 

 between the 43rd and the 47th parallels would have the sun in the zenith at noon and at 

 the same time enjoy a 24 hours day. At the summer solstice the total area of the region 

 having a 24 hours day, that is the region polewards from the 43rd parallel, would be 

 31,2G9,500 square miles, or 15*9 per cent, of the whole* earth's surface, the two polar 

 caps together amounting to 31*8 per cent. At this time the other pole, turned away 

 from the sun, would be undergoing a regular alternation of day and night, the longest 

 night being one of 12 hours, and even that would be only at the pole at the instant of 

 the solstice. The region of a possible 24 hours day at present has an area of about 

 16,674,200 square miles, or 8 '38 per cent, of the earth's surface, only 26 per cent, of 

 what it must have been with a sun of the size above indicated. The complete annihila- 

 tion of the 24 hours polar night, and the almost perpetual insolation near the pole (only 

 interrupted for a few hours at the winter solstice), would go far to counteract the 

 diminution of energy due to the obliquity of the sun's rays. We must also take into 

 account the fact that the nearer to the pole we go, the higher is the elevation of the sun 

 at midnight, although lower at noon. On the whole, then, we would expect in the tropics 

 warm days and cold nights, and in circumpolar regions cooler clays and mild nights, the 



