64 PROCEEDINGS OF SECTION A. 



each star, the one for its right ascension and the other for its 

 declination ; and it is probable that one worked at each instrument, 

 but it was soon found that the transit was very defective and gave 

 such unsatisfactory results that it was worse than useless. We are 

 not told when its use was given up ; but we are informed (Tntrod. 

 Parramatta Catalogue, p. 7), that during the greater part of the 

 time embraced by the Parramatta observations, Mr. Dunlop was 

 the only observer* ; and, with a view to complete the observations 

 for the formation of an extensive Catalogue he abandoned the 

 Transit instrument, and fixing the Mural Circle as nearly in the 

 plane of the meridian as he could, he commenced observing every 

 star that circumstances permitted, as it passed the central wire 

 registering the time of transit, and I'eading off as many 

 microscopes as the interval, before another object came to the 

 wire, would allow. 



In the period of about two years and a-qviarter he observed in 

 this manner above 7,000 stars, and made nearly 40,000 observa- 

 tions, besides an extensive series of observations upon double 

 stars and nebulae, an amount of labour which, perhaps, has never 

 been performed before by any one within the same time. This 

 change of instrument was made during the time Sir Thomas was 

 there, and must have been with his consent, and it is very much • 

 to be regretted that it ever was made, as it would seem for the 

 purpose of observing a great number of stars ; because the 

 Catalogue is practically useless, and its weakest point is the right 

 ascension of the stars, and bad as the old transit instrument was, 

 I know from working with it that it was capable of giving very 

 much more accurate right ascension results than the mural circle, 

 which has a short axis, and such a form of construction as to render 

 accurate work in the meridian impossible ; and there can, I 

 think, be no doubt that the time mentioned, two and a-quarter 

 years, is wrong, for the following reasons : — Rumker left the 

 Observatory 16th June, 1823, and Dunlop on March 2nd, 1826 

 (Introd. Parramatta Catalogue), an interval of two years and eight 

 months, and he says in a letter to Sir Thomas Brisbane (Royal 

 Astronomical Society's Memoirs, Vol. III., p. 257), that he stayed 

 behind to follow out his favorite study, i.e., double stars and 

 nebula?, the meridian work in the Observatory having prevented 

 him from doing so. He does not say how long he spent over 

 this work, but it is evident from an extract which follows that 

 he arrived in England in time to reduce most of these observations 

 there, and have them ready to be presented to the Royal Society 

 on 20th December, 1827. They did not require much reduction ; 

 probably a month would be time enough. Allow four months for 



* I cannot find anything: to shew how much work had been done towards the Catalogue 

 when Rumker left the Observatory. Except that in January 1823, Sir T. Brisbane writing 

 of Rumker, says, nearly ten thousand stars have been observed (i e. in eig-ht months), 

 perhaps it should read, observations have been made for the finished catalogue has not one 

 thousand stars in it, and most of that work was done by Dunlop. 



