COMMENTATIO ASTRONOMICA. ^9 



Differt autem observationes Aquilae at, Societali recitandas. 



Tandem, 16 Aprilis 1818, eventum refert observationutn x Aquilae (*). 



« It has often been proposed to examine the parallas of a large star by comparing it 

 « ■with a smaller one; but to do tliis by meridian observations is very difficull , and in 



« most cases impossible , from some peculiar practical difficulties Relatively to 



« « Aquilae, it fortunately bappens, that l Pegasi is so situated as to be very advan- 

 « tageously employed. " 



Noudum omnes , sed meliores tantum , computavit , Cifgneis tarnen longa poslponeudas. 

 Observationum 54, in quatuor series aeqiiales divisarum , hi sunt evenlus; 



Tempora serierum. Diff. declinalionis Aquilae » el Pegasi /. 



1817, Jubi 25 — Augusti 25 1' 49",17 



Augusti 25 — Septembris 8 49, 20 



Septembris 8 — Novembris I 49, 61 



Novembris 1 — Decembris 29 48, 57 



« I can discern no appearance of parallax in the above observations; and indeed I 

 « have long considered it as a hopeless task to establish its existence by observations on 

 « a Star so far from the zenith. " 



« After so many fruitless attempts to establish the existence of sensible parallax , I was 

 « much disposed to abandou all farther prosecution of this subject , when my anxiety 

 K was again renewed by the paper lately communicated to the Society by Dr. 

 « Brinkley. " 



§ n. 



Ergo, priusquam pergamus, audiendus est Brinkleius, qui seripsil 20 Februarii 

 1818 (t): 



Post observationes supra cum Maskelynio comraunicatas « I have met with apparent 

 « motions in several of the fixed stars , the cause of which I was unabte to explain , 

 « unless by atlributing them to parallai. Among these stars « Aquilae exhibited' the 

 « grealesl change ofplaee. '* 



«r 



(*) Phil. Trans. )8i8. P. 11. p. 477. Tora. CVnr. xxT. TitalUs est; On the paraUax of a Aqui- 

 lae, Äy John P ond, F. B. S. Astronomer Royal. 



(*) Ibidem p. 875. xn. Titulus est: On the parallax of certain fixed stars. Bj the Rev John 

 Brinkley, D. D. F. R, S. and Andrews Professor of Asironomy in the University of Dublin. Ci- 

 tat autem Traasacliones Academia^ Regiae Hibernicae, i8i5. Vol. XII; 



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