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HISTORY OF PHYSICAL ASTRONOMY.

ceeded to carry his design into effect, with all the energy which the con-sciousness of a just cause, and a laudable desire to set himself right inthe eyes of posterity, were capable of inspiring. His constitution, how-ever, already shattered by the incessant inroads of ill health, and nowsinking under the frailties of old age, was inadequate to the completeexecution of a task of such magnitude. It was contemplated by him topublish the results of his labours in three volumes; but he had barelysucceeded in completing the second volume when he died, on the 31st ofDecember, 1719. The preparation of the third volume for the press, waseffected by the voluntary exertions of Crosthwait, his assistant at the timeof his death, and the famous Abraham Sharp , who had also at one timeserved him in the same capacity, and had ever since continued his devotedfriend*. The whole work was finally published in the year 1725, inthree volumes folio, under the title of “ Historia Ceelestis Britannica,”The first volume contains extracts from the observations of Gascoigne andCrabtree from 1038 to 1043, also Flamsteed’s own observations at Derbydown to 1075, and his subsequent observations at Greenwich with thesextant from 1075 to 1689. It comprehends, moreover, various subsidiarytables to be used in calculation, and also the places of the moon and pla-nets deduced from the observations. The second volume contains theobservations made with the mural arc from 1689 to 1719 j. At the end ofthis volume, also, there is a collection of useful tables, and a list of theplaces of the moon and planets computed from the observations. Thelast-mentioned results, as well as the corresponding results in the firstvolume, exhibit not only the right ascensions and polar distances of theseveral bodies, but also their longitudes and latitudes. The third volumecommences with the Prolegomena, in which Flamsteed takes a rapidsurvey of the progress of astronomy, concluding with a description of hisown instruments and methods of observation. There are next insertedcopies of all the catalogues of the fixed stars that had been executed byastronomers previous to the time of Flamsteed. These are succeeded byFlamsteed’s own catalogue, which exhibits the right ascensions and polardistances, as well as the longitudes and latitudes of 2935 stars, reducedto the beginning of the year 1689, together with the annual variations inright ascension and polar distance, arising from the regression of theequinoctial points. At the end of the volume there are various subsidiarytables designed for abbreviating the labours of calculation.

* Sharp resided at this time in Yorkshire . He also assisted Crosthwait in the preparationof the maps of Flamsteed’s Atlas, which was published in 1730. The following passage ofa letter from Crosthwait to Sharp , dated January 27,1721-22, reflects so much credit uponall the parties alluded to, that it cannot fail to prove acceptable to the reader:—" I am muchconcerned to find, by yours of the 2nd instant, that you had entertained the least suspi-cion of being forgotten or slighted by me, though there had been nothing more for youto do. I can assure you, with the greatest sincerity, that I shall for ever (though 1 amsure I shall have no share in the profits) retain a grateful remembrance of the generousand kind assistance you have given towards completing Mr. Flamsteed’s works, and shallbe ready at all times hereafter, so long as life endures, when in my power, to return yougratitude ; and the memory of the ingenuous and disinterested Mr. Sharp will always,by me, be had in the greatest esteem, next to that of my deceased and good friendAir. Flamsteed.” (Baihfs Life of Flamsteed, p. 346.) Mrs. Flamsteed died in 1730,without leaving a single farthing either to Crosthwait or Sharp , notwithstanding their dis-interested exertions in her behalf during a period of ten years !

+ At the top of each page of observations in this volume the error of collimation ofthe instrument is inserted.