GREAT REFRACTING TELESCOPE AT ELCHIES, IN MORAYSHIRE. 413 



a different and a conspicuous double star near the boundary of the field ; and on 

 bringing this stranger into view with the great telescope, it prqved quite a 

 splendid object, which I measured, as recorded above ; and was much surprised 

 to find that there was no mention whatever of its existence in the " Cycle," which 

 mas my only hook of reference at the time. I wrote, therefore, to Professor Grant, 

 when on my road home from Elchies, sending him these observations, and saying 

 that the star was new to me, and foreign to the " Cycle," but so brilliant and 

 richly coloured, that it could hardly have escaped all former observers. But then 

 it was, that the Scottish historian of astronomy soon identified the star for me 

 with Struve's 2841 ; and assisted in establishing, in as far as two observations 

 alone can establish, that an Elchies measure whether in magnitude, colour, posi- 

 tion, or distance, is not unworthy to stand side by side with an equally small 

 fragment of the noble work of the great Russian astronomer, the maker of 

 Dorpat's fame, and the founder of Imperial Pulkova. 



Part C. — General Deductions. 

 Part C. — 1. Instrumental Qualities. 



When the recorded particulars, of what was done with the Elchies telescope 

 during my period of trying it, extend through so many pages as the preceding, a 

 few words on the final results of the whole may not be out of place. 



Now, firstly, and most conspicuously, it was by general consent a big tele- 

 scope, — viz. with an object-glass of 11 inches in diameter. Was it found, then, to 

 possess optical advantages commensurate with that size ? 



This is an important question to many parties ; for mere size, without other 

 advantageous qualities, will only prove a drawback, and of a very positive and 

 incommodious character in the use of any instrument ; and while size and its 

 expected power form the chief point upon which tlie general public desires to be 

 informed, it is also one where amateurs are often exceedingly sensitive; for many 

 a man who has in his day provided himself with one of the largest object-glasses 

 of that period, is not particularly delighted when a detir friend, only a few years 

 i afterwards, profiting by the manufacturing progress of the age meanwhile, is 

 I enabled with ease greatly to exceed him. 



It has recently been said too, by a gentleman who has had possession for 



! many years past of an 8'5-inch object-glass, and with reference to this present 



I testing of the 11-inch telescope of Elchies, that you can always, — without any 



j looking through at the heavens, and by merely measuring with a carpenter's rule 



the area of any big object-glass, — compute quite near enough what is the smallest 



isolated star it will show, if its composition be but decently good ; that actual 



astronomical observations to such an end, are therefore idle and useless ; and 



