46 LIGHT SCIENCE FOR LEISURE HOURS. 



ENCKE THE ASTRONOMER. 



THE years which have passed since Encke died have 

 witnessed notable changes in the aspect of the science 

 he loved so well. But we must look back over more 

 than half a century, if we would form an estimate of 

 the position of astronomy when Encke's most notable 

 work was achieved. At Seeberge, under Lindenau, 

 Encke had been perfecting himself in the higher 



members of St. John's College, Cambridge. Although my paper in 

 the Quarterly Journal of Science was written quite independently of 

 Mr. Wilson's (which, however, I had read), yet it chanced that in 

 describing the same mathematical relations, and the same sequence 

 of events, I here and there used language closely resembling his. 

 I fear this led for a while to some misconception ; but I was for- 

 tunately able to show in Mr. De la Rue's address to the Astronomical 

 Society, on the same subject, passages yet more strikingly resem- 

 bling some in Mr. Wilson's paper (written subsequently and quite 

 independently). The fact would seem to be that if two persons 

 describe exactly the same events, and deal with exactly the same 

 mathematical relations, it is almost certain that in more than one 

 passage' they will use somewhat similar expressions. 



I was actually indebted to Mr. Wilson's paper for one illustration, 

 however, that derived from the movements of a supposed artificial 

 moon; and I think that had his paper appeared in a magazine 

 printed for general circulation, I should have referred to it. As it 

 was, this seemed useless so far as the readers of the Quarterly 

 Journal of Science were concerned. The circumstances of the case 

 were, indeed, far from calling for a reference ; while I had in a 

 sense made the illustration my own by detecting an important mis- 

 calculation in the original (the amount of advance being either 

 doubled or halved I forget which). Had I referred to Mr. Wilson's 

 paper, I must needs have mentioned this mistake ; and it would have 

 appeared as though I had had no other purpose in making the reference. 



I mention these matters to explain what I fear my esteemed 

 fellow-collegian was disposed at the time to regard as either a wrong 

 or a slight. Nothing was further from my intention than either. 



