214 METEOROLOGY. 



at each polo the following phenomena would result: — Durincf three 

 months the sun would ascend, apparently, by reason of the diurnal revo- 

 lution, spirally from the horizon to the zenith ; every diurnal revolution 

 marking the sun's place when on the meridian at a higher and still 

 higher altitude, until at length his unmitigated rays, for a long time 

 vertical, or nearly so, and unrelieved by the cooling shades of night, 

 would produce a temperature far exceeding that of the most sultry 

 regions of the torid zone ; during the succeeding three months the sun 

 would in the same manner decline towards the horizon, and after re- 

 maining visible uninten-uptedly for six months, would then set; during 

 the other six months he would never rise, and probably, from the rapid 

 radiation which would then set in, winter the most intense and pro- 

 tracted would soon ensue. On the other hand, at the equator, there 

 would annually prevail two tropical summers and two polar winters. 

 In our latitude the sun would, in summer, remain for more than two 

 months constantly above the horizon, for the most part nearly vertical, 

 and in winter during the same space of time would be constantly 

 below it. From the great changes which would necessarily result 

 under such a state of things it is impossible to predicate the effects ; 

 but from the long continued and intense action in ofie direction, it is 

 probable that in the hot seasons tremendous deluges of rain, and 

 unparalleled and devastating tornadoes would sweep the surface, 

 whilst in winter, the intense radiation would produce a temperature 

 as low as that of the present polar regions. At all events it is clear, 

 that man, as now physically constituted, could no longer inhabit this 

 planet. Now since the earliest recorded ages the inclination of the 

 ecliptic has been decreasing at the rate of 47'' per century, by this 

 amount tending to modify the extremes of summer and winter, and 

 to produce in every climate a smaller annual fluctuation ; the amount 

 is small, but it is certain that if it go on indefinitely, it must result 

 in catastrophe ; because, after the inclination has become zero, and 

 produced equal day and night throughout the year over the earth's 

 entire surface, it may again increase until it become the greatest 

 possible — namely, at an angle of 90<^ with the equator. Here again 

 the profound research of a late eminent astronomer has led to the 

 demonstration of a theorem, (the expression of which is very similar 

 to that by which the ultimate stability of the eccentricities is proved.) 

 which shows that all the changes of inclination will perpetually oscillate 



