GREAT REFRACTING TELESCOPE AT ELCHIES, IN MORAYSHIRE. 373 



have counterpoise weights beyond. These shutters were always most satisfactory 

 and true in their movement, opening and closing with facility, and either offering 

 a very large and broad view of the heavens, or keeping out both wind and wet 

 with perfection. 



The equatorial moimting is of that character usually known as the German ' 

 variety in form, though in this instance it is constructed in the stronger manner 

 of English engineering work ; and has been so abundantly described already in 

 print — 1st, in the Jury reports of the Exhibition of 1851 ; and, 2d, in the Royal 

 Astronomical Society's Monthly Notices for November 1862 — that little more need 

 be said of that part of the subject here. Though indeed it is proper to record, 

 considering the great size and weight of the instrument, that I found the hand- 

 ling and working of it by myself alone, far more easy than I had expected ; ex- 

 periencing too, throughout the whole of the observations, a remarkable freedom 

 from tremors either of tube or mounting ; a consequence, without doubt, of the 

 superior weight, and very massive construction of all those larger parts, which the 

 optician, Mr Ross, had wisely confided to the hands of the well-known manu- 

 facturing firm of Ransomes and May, at Ipswich, to execute for him. 



A. — 3. Prejiarations for Observing. 



These preparations consisted in little more than cleaning the instrument from 

 old and hardened oil, cleaning both outer and inner sides of object-glass, but with- 

 out separating the lenses ; removing paint from, and brightly polishing, the outer 

 surface of the metal dew-cap ; reddening the lamp illumination of the field of 

 view, determining the magnifying power of the eyepiece employed throughout 

 (and found to be 397),* testing the equatorial adjustments and micrometer values, 

 chiefly by daylight observations on known stars, and then in preparing the list 

 of objects to be examined. These were, for the most part, selected from the 

 double and compound stars which I had begun to observe on the Peak of Tene- 

 riffe in 1856, but had had no opportunity of reobserving since then. 



It was part of the preparation also to endeavour to form some idea of the 

 quality of the object-glass about to be employed ; an object-glass which, though 

 furnished by Mr Ross, is said to have been actually constructed in the optical 

 factories of Munich. There are many small bubbles in the material, but no percep- 

 tible striae ; and the discs which are given to the stars when in focus are extremely 

 small, — so small that the two stars B and C of 7 Andromedse, stars of the fi.fth 

 I and sixth magnitudes respectively, and 0'6 of a second apart, were on one occa- 



* This high power could be kept constantly on, without inconvenience when first picking up 



'any small star, owing to tlie luxurious furnishing of finders to the large telescope, for it had no less 



than tliree such appendages ; wliereof the first had a 4- 5-inch object-glass, and a magnifying power 



of 56 times ; the second, a 2-2-inch object-glass, and magnifying power of 28 times ; and the third, 



a l"7-inch object-glass, and magnifying power of 17 times. 



