Jan. 30, 1SS5 | 



♦ KNOWLEDGE ♦ 



SO 



OKBIT OF THE EARTH 850,000 YEARS AGO. 

 The points h and h' are those reached at the middle of the intervals between the passage of A, the aphelion, and A', the perihelion. 



be in the future much less than it is now ; while again it 

 has in the past often been far greater than at present. 



The figure is a picture of the earth's orbit, which I 

 originally drew for an illustration to my article on 

 astronomy in the '• Encyclopadia Britannica. ' The orbit 

 of the earth is represented as it was 8.iO,000 years ago, at a 

 time when it had very nearly its greatest possible eccen- 

 tricity. Instead of the eccentricity being as now only about 

 one-sixtieth, it was at that time nearly a thirteenth of the 

 mean distance. In other words, instead of the earth rangirg 

 about 1, -500, 000 miles on either side of her mean distance, 

 she then ranged about 7,000,000 miles from and toward 

 the sun, making a total range of distance of about 

 14,000,000 miles. At that time then, very much more 

 remarkable varieties of climate must have e.visted on the 

 earth than now. Taking the distance when the eaith was 



furthest from the sun, at her mean distance from the sur 

 and at her least distance, at 14, 1.!. and 12, the supplies ot 

 solar heat when the earth was so situated were as 11, 13. 

 and 15, or — nearly enough — as •">, G, and 7. So that when 

 the earth was in perihelion she received 40 per cent, morv- 

 heat than when she was in aphelion. 



It so chanced that then, as now, the time of nearest 

 approach to the sun occurred in the winter months of thi 

 northern hemisphere, (about Deeember 1 instead oi- 

 January 1); but that relation has several times beer., 

 reversed since, and had been several times rever.sed before. 

 (To lie concluded.) 



A.N American blacksmith has patented a cart having four higl. 

 wheels, the horse being harnessed nndernoatb. When going dowi; 

 bill the horse is raised by a broad belly-band, and sn has a re.'it {') 



