390 PEOFESSOR C. PIAZZI SMYTH ON THE 



2d, The increase of position angle of A and D ; 



Zd, The increase of distance of A and D ; and, 



Uh, Most strange of all, the colour of A, as assigned by Struve ; for he, as 

 well as the Cycle, makes it yellow ; and either his recorded colour must be 

 repudiated by the repudiator of the Cycle, or the modern change in that star's 

 colour must be allowed to be real. 



The observations now given under the head of Lilburn Tower, are some 

 which I was kindly allowed to make when on a visit last December to my friend, 

 Mr E. J. CoLLiNGWOOD. His observatory, planned and erected by himself, is a 

 model of perfection in everything which it contains, and is furnished, among 

 other instruments, with an equatorial, whose object-glass, a Munich 6-inch, had 

 been purchased from the late Charles May, C.E., and by him procured from Mr 

 Dawes, under the statement of its having come out of long and very severe trials 

 for defining power, with the most remarkable success. The mounting is by Simms, 

 with some fittings by Dollond, in excellent style. Nothing, therefore, was 

 wanting to enable good observations to be made, at least my best, excepting good 

 atmospheric definition. Now both the nights that I observed the object at 

 Lilburn Tower, were stormy in the extreme, and the definition as bad as on the 

 two when I observed it at Elchies with Mr Grant's larger telescope ; and I have 

 described over and over again how bad it was there, in the November Monthly 

 Notices, see pages 3 and 13, as well as indicated the same in the small weights 

 attached to the measures (weights giving much below the smallest weights ever 

 assigned by most other observers to their worst measures). In such a state of 

 atmospheric definition, two small, and very close, blue stars, as A and B are 

 now asserted to be, might easily have been confounded together ; and I would 

 not have undertaken to decide on the question in that shape at that time 

 i. e., either at Elchies or at Lilburn. But it was not then in that shape to me; 

 for, with the Cycle in my hand, a crowned book, stating, and having stated un- 

 questioned during eighteen years, that the group is " an exquisite object," and 

 " an admirable test to try the light and definition of a telescope ;" and describing 

 its three closer members, or A, B, and C, thus: — viz., a large yellow star, A, with 

 one small blue one close to it, and another small blue one a moderate distance 

 off; and then, looking into the telescope, and seeing no trace of a yellow star of 

 any size, big or little, in that place, and only two faint blue burred images there, 

 at just about the distance apart of the two small blue stars, B and C, of the Cycle, 

 — I thought, and still think, myself justified in publishing, that no large yellow 

 star now exists, where the Cycle stated that sucli a one existed in its day. So 

 far, too, as the subsequent discussion at the Royal Astronomical Society has 

 elicited, the Elchies observation was the first to announce that fact, — a most 

 notable one surely in reference to a " telescopic test object," whether originating 

 in a mistake in the Cycle, or a cosmical change in the starry heavens. 



