PROCEEDINGS OF THE BOARD OF REGENTS. 221 



LETTERS PRESENTED TO THE BOARD OF REGENTS TO ILLUSTRATE THE 

 CORRESPONDENCE AND OPERATIONS OF THE INSTITUTION. 



Communication from Dr. B. A. Gould, on a new discussion and reduction of the 

 observations of Piazzi of Palermo. 



Cambridge, May 16, 1863. 



My Dear Sir : For many years I have been strongly convinced that an 

 •extremely valuable contribution to astronomical science might be made by a 

 new discussion and reduction of the observations of Piazzi at Palermo. 



This eminent astronomer, with his assistants, was engaged, during the twenty- 

 two years from 1792 to 1813, in observing the positions of the principal fixed 

 stars. He was provided with the best instruments which could be obtained at 

 that time, and his observations have been, and must continue to be, our prin- 

 cipal and most trustworthy source of information as to the places of between 

 seven and eight thousand fixed stars at the beginning of the present century. 

 As nearly as I can estimate without an actual count, he must have made about 

 ninety thousand determinations of right ascension, and from sixty to seventy 

 thousand of declination, the original records of which observations still exist. 

 From these he constructed his two well-known catalogues — the first in 1803, 

 the second in 1S14 — containing the mean places for 1800.0 of 7,646 stars. 



His methods of observation, while, of course, far inferior in many respects to 

 those of the present day, were the best in use at that period ; and the care and 

 fidelity with which they were used seem to have been unsurpassed ; and, al- 

 though the reductions upon which the catalogue was based seem to have been 

 incommensurate in precision with the observations themselves, still this cata- 

 logue has, for the past fifty years, been a standard authority with astronomers, 

 and, for a great part of that time, their chief dependence for both the right 

 ascensions and declinations of stars. 



The original observations of Piazzi were sent by him for safe keeping to his 

 friend Oriani, in Milan, and have been carefully preserved at the Observatory 

 of the Brera in that city. In 1S45, Professor Littrou, the director of the Impe- 

 rial Observatory of Vienna, incited specially, as he says, by Argelander, and 

 encouraged by Bessel, Gauss, Schumacher, Struve, &c, commenced the printing 

 of these original observations as part of the series of Annals of the Vienna 

 Observatory, and they have thus been for several years accessible to astronomers. 



When organizing the Dudley Observatory in 1856-'5S, it formed an integral 

 part of my plan, not merely to institute new observations of the heavenly bodies, 

 but to carry on such computations, reductions, &c, as might render available 

 past observations of this and the last century, which would otherwise be either 

 useless or of inferior value to astronomy. Various undertakings of this kind 

 were planned, but the first of all to be begun was the re-reduction of the whole 

 series of Piazzi's observations, using the best values of the constants of pre- 

 cession, aberration, and mutation, and investigating all the instrumental errors 

 with care ; and I made considerable progress in arranging the details of the 

 computation. After communication with Professor Littrou, and an extended 

 correspondence with Professor Argelander on the subject, in which this distin- 

 guished astronomer gave me many very useful suggestions, the whole plan was 

 completed, and, but for the misfortunes which interfered with the usefulness 

 of the Dudley Observatory before its activity had fairly begun, the new cata- 

 logue would doubtless now have been in the hands of astronomers. 



My health and opportunities of labor being now greatly improved, I am 

 anxious to resume this Avork, and write to ask for your influence and aid, as far 

 as possible, in furtherance of the plan. Knowing, as you do, the nature of the 



