OUTLINES OF NATUEAL PHILOSOPHY. 



tions in the kalender, and the real motions of the 

 sun, should always be the least possible, is not 

 thereby completely resolved. The modes of in- 

 tercalation best suited to that object, require all 

 the integer numbers to be found which most near- 

 ly express the ratio of the fraction .212264- to 1, 

 See EULER, Siemens d'Algebre, torn. n. ; Addi- 

 tions by LA GRANGE, 20. 



Secular Variations in the apparent Motion of 

 the Sun. 



The variations in the sun's motion which have now 

 been described, are confined within short periods, 

 during which they alternately increase and dimi- 

 nish. There are others, which go on from one 

 age to another, and are either continually pro- 

 gressive, or circumscribed by periods of very long 

 duration. These are so slow, that they are only 

 perceived by comparing together observations 

 made at a great distance of time. They are call- 

 ed Seculur Inequalities. 



111. By comparing very distant observations, 

 it is found that the line of the apsides, or the 

 longer axis of the sun's orbit, has a progressive 

 motion, or a motion eastward : so that the apsis 



recedes 



3 



