CHAP. III., 1.] 



ASTRONOMY. MASKELYNE DELAMBRE. 



were both distinguished by modesty, simplicity, and 

 love of truth. Of all their contemporaries of emi- 

 nence, few escaped so happily from the unprofitable 

 strife of rivalry and personal disputes, and none ex- 

 hibited a more impartial desire for the advancement 

 of the science to which they were devotedly attached. 

 Perhaps neither was a man of lofty talent, yet they 

 did not fail to secure deserved respect in their own 

 day, and far more gratitude from the posterity whom 

 they essentially benefited than falls commonly to 

 the share of men of higher pretensions in this re- 

 spect. Both their names are important links in the 

 history of astronomy. 



(150.) NEVIL MASKELYNE, born in 1732, and educated at 

 ukelyne; Cambridge, was early attached to astronomical pur- 

 suits. After various minor services connected chiefly 

 with navigation and the discovery of the longitude, he 

 attained the honourable post of Astronomer Royal, 

 which he filled from 1765 till 1811 with distinguished 

 success. His immediate predecessor was Dr Bliss, who 

 held the office for but three years and without dis- 

 tinction. Practically, Maskelyne may be said to have 

 succeeded Bradley, probably the greatest astronomer 

 whom England has yet seen, whose discoveries have 

 been recorded in the last Dissertation, and whose 

 observations, through a variety of circumstances, were 

 destined rather for the benefit of the nineteenth cen- 

 tury than for his own. Maskelyne wisely recollected 

 that the observatory was mainly founded for the 

 improvement of navigation, 1 and one of his earliest 

 labours was the establishment in 1767 of the "Nau- 

 tical Almanac," a work based on the best astronomi- 

 cal observations and of the highest service to seamen. 

 " During Maskelyne's long tenure of office he was 

 entirely devoted to its duties, making himself all the 

 most delicate observations, particularly those of the 

 moon, and rarely quitting the observatory except to 

 attend the meetings of the Royal Society. The per- 

 fect method and continuity of his observations give 

 to them a great value, especially for the correction 

 of the Lunar Tables, in which respect they are indeed 

 without a parallel. But the regularity of their 

 publication was not their least merit. Four large 

 folio volumes include the patient labours of a life 

 (for he had but one assistant). Delambre in his 

 character of Maskelyne says, that if through some 

 catastrophe the whole materials of science should be 

 lost, except these volumes, they would suffice to re- 

 construct entirely the edifice of modern astronomy." 2 

 In fact, on Maskelyne's accession, the only methodi- 

 cal publication which had issued from Greenwich 

 Greenwich. Observatory was the " Historia Celestis" of Flam- 

 steed ; Halley's, Bradley's, and Bliss's observations 

 remained in manuscript. A like fate attended most 



value of 

 his obser- 

 vations at 



of the foreign astronomical observations ; labour! 

 the most irksome and conscientious lie buried in 

 piles of MS. useless to science, and which therefore 

 might almost as well have never been made. This 

 is particularly the case with the Parisian observa- 

 tions (as the impartial Delambre records with pain), 

 commenced even before the time of Flamsteed ; but 

 which, owing to this cause principally, have remained 

 even to the present day (and it is forty years since 

 Delambre wrote his patriotic protest) without con- 

 tributing materially to advance astronomy. Let it 

 then be recorded to the honour of Maskelyne, that 

 this important step of regular and full publication 

 at the public expense was entirely due to him. His 

 places of the sun, moon, and planets, were the founda- 

 tion of the improved theories of physical astronomy, 

 then more ably cultivated on the Continent than in 

 Britain, and of the tables also chiefly furnished by 

 German and French computers. 



Maskelyne's more important contributions to (151.) 

 science may be briefly stated under these two heads ; 

 The determination of the Lunar orbit from observa- 

 tion, and its application to navigation ; and the de- 

 termination of the local attraction of Schehallien and 

 of the density of the earth. 



I. The determination of the Lunar Orbit from Ob- (152.) 



servation and its application to Navigation. Though ^unar ob- 

 / i i 3 .-,.> , servations. 



astronomy owes (as we have already said) much to 



Maskelyne in the exact determination of the places 

 of the sun, planets, and the most conspicuous fixed 

 stars, the comparison of the Lunar place with the 

 tables was by far the most arduous and the most im- 

 portant of his undertakings. I.t was the most ardu- 

 ous, because, from the extreme complexity of the 

 moon's motions, every part of its orbit must be nar- 

 rowly watched, requiring the astronomer's presence 

 at his instruments at all possible hours during the 

 course of a lunation, these motions being subject to 

 important changes which recur every nineteen years, 

 besides others of yet far longer duration. It was 

 Maskelyne's good fortune, and at the same time the 

 reward of his perseverance, to watch three revolu- 

 tions of the lunar nodes. He did not content him- 

 self, however, with making observations ; he contri- 

 buted in every possible way to the improvement of 

 the tables of the moon's motion. He was in con- 

 stant communication with Mayer, one of the ablest 

 astronomers of his day, and he directed the calcula- 

 tion of Bradley's observations by Mason, for the far- 

 ther improvement of Mayer's Tables. Maskelyne's 

 own observations, to the number of at least 5000, 

 were used by Burg in his excellent tables of the moon 

 which have even yet been hardly surpassed ; but 

 their full value has only been tested recently by the 



1 In the warrant appointing Flamsteed to be the Royal " Astronomical Observator," his duty is declared to be " to rectify the 

 tables of the motions of the heavens and the fixed stars, so as to find out the so much desired longitude at sea, for perfecting the 

 art of navigation." 



2 . From an article on Greenwich Observatory in the Edinburgh Review, written by the author of this Dissertation. 



