290 LIGHT SCIENCE FOR LEISURE HOURS. 



Now, undoubtedly, if any relation of this sort could be 

 established, the problem would be solved ; but as a 

 matter of fact no such relation exists, and the solu- 

 tion of the problem does not require that there should 

 be any relation of the sort. For example, we do not 

 look on the determination of the diagonal of a square 

 (whose side is known) as an insoluble, or as otherwise 

 than a very simple problem. Yet in this case no 

 exact relation exists. We cannot possibly express 

 both the side and the diagonal of a square in whole 

 numbers, no matter what unit of measurement we 

 adopt: or, to put the matter in another way, we 

 cannot possibly divide both the side and the diagonal 

 into equal parts (which shall be the same along each), 

 no matter how small we take the parts. If we divide 

 the side into 1,000 parts, there will be 1,414 such 

 parts, and a piece over in the diagonal ; if we divide 

 the side into 10,000 parts, there will be 14,142, and 

 still a little piece over, in the diagonal ; and so on for 

 ever. Similarly, the mere fact that no exact relation 

 exists between the diameter and the circumference of 

 a circle is no bar whatever to the solution of the great 

 problem. 



Before leaving this part of the subject, however, 

 I may mention a relation which is very easily re- 

 membered, and is very nearly exact much more so, 

 at any rate, than that of Archimedes. Write down 

 the numbers 113,355, that is, the first three odd 

 numbers each repeated twice over. Then separate the 

 six numbers into two sets of three, thus, 113) 355, 



