LISLE. 7yi 
Catharine to M. de Kyrilow, firft fecretary of the fenate, 
to furnilh him with all the maps and memoirs which were 
fent to that body ; and he received geographical commu¬ 
nications from M. Latifchow, the l'ucceffor of M. Kyri¬ 
low, and from feveral pfrfons connected with the admi¬ 
ralty, the college of war, and the department of engi¬ 
neers. At length, he was able to announce to the academy 
that he had completed his plan for a Ruffian atlas, and 
propofed to publiffi it ; but that undertaking was pro- 
craftinated till after his return to France, when the work 
made its appearance in twenty-one maps, at full in the 
Ruffian language, and afterwards in Latin. On a fubfe- 
quent companion of thefe maps with the Iketches which 
he had himfelf made at Peterfbnrg, M. de Lille found 
them to differ fo materially from his colledlions, that he 
formed a defign of engraving them anew at Paris, more 
correctly, in a better tafte, and on a larger fcale, accom¬ 
panied with exaft defcriptions of the countries, and an 
account of the authorities on which they, were founded. 
His labours for this purpofe form a part of the manu- 
fcripts which he left behind him, and which were depo- 
iited in the king’s library. 
Intimately connected with aftroncmy are meteorolo¬ 
gical obfervations; and thefe M. de Lille regularly made 
during forty years, with incredible exaflnefs. The ther¬ 
mometers which he ufed for this purpofe, till the yeas 
1731, were thofe of Reaumur, which are the moll perfect 
of the fpirit kind, though not without their inconveni¬ 
ences. Thofe he at .that time correifled, in a conliderable 
degree, by making them of mercury, on the fame princi¬ 
ple. In his thermometer, the point at which the gradu¬ 
ation commences is that to which the mercury is railed 
by the heat of boiling water; and, contrary to the com¬ 
mon order, the feveral degrees are marked from this point 
downwards, the numbers increafing as the heat decreal'es, 
and the freezing point being at 150. 
We have already obferved, that while M. de Lille was 
difcharging the duties of his appointment with the greateft 
zeal and diligence, he met with many obltacles and dif- 
couragements, which, after he had been feven years in 
Ruffia, increafed rather than diminilhed. The neceffary 
affiftants in making his obfervations were gradually with¬ 
drawn ; the inftruments which had been promifed were 
not procured: the fums requifite for defraying the ex- 
penfes of the obfervatory were withheld ; and the arrears 
of his penfion were fullered to accumulate. Thefe cir- 
cumftances made him difgufted with his fituation ; and, 
In the year 1734, he wrote to M. Blumentroll, and to M. 
de Keyferling, prefident of the academy, for permiffion to 
return to France, and the payment of his arrears ; but he 
could not obtain either the one or the other. At length, 
after almolt annually requelling his difmiffion for thirteen 
years, M. de Lille obtained it in 1747; 'and, taking his 
leave of Peterlburg in the month of May, he arrived at 
Paris in September of the fame year. Soon after, he was 
appointed profeffor of mathematics at the college-royal ; 
in which fituation he lived to render the greatelt fervice 
to the intereft of fcience, by training up pupils worthy of 
fuch a mailer, and formed to proceed with ardour and in¬ 
defatigable perfeverance in the fame glorious career. In 
this number were the celebrated Lalande, and M. Meffier. 
But this employment did not prevent M. de Lille from re¬ 
luming with new vigour his allronomical labours. At firft 
he made fome obfervations at the royal obfervatory; but 
foon removed to the Hotel de Clugny. His profefforlhip 
brought him in no more than nine hundred livres a-year ; 
but with this income, and the produce of the arrears of 
bis penfion which were paid him before bis departure 
from Peterlburg, he was content. Indeed, he expended 
no fmall part of the latter, in building and furniffiing with 
proper inftruments an obfervatory on the flat top of the 
Hotel de Clugny. Here he recommenced his obferva¬ 
tions, and continued them without interruption during 
twenty years, both night and day, in winter as well as 
fummer, very commonly attended by his illultrious pupil 
Lalande. In the year 1748, his pupil M. Monnier took 
a voyage to Scotland, to oblerve one of the moll interell- 
ing eclipfes of the fun which had appeared for a long 
time, it being annular, and furnilhing an opportunity for 
meafuring the diameter of the moon, at the time when it 
fhould be entirely vifible on the fun’s cliIk. On this fub- 
jetl M. de Lille publifhed a large advertifement, which 
was a complete treatile on annular ecliples. The obfer¬ 
vations, which he afterwards received from his correfpon- 
dents, induced him to enter more fully on the confider- 
ation of the theory of eclipfes, and he communicated a 
part of his refearches on this lubjeft to the academy in 
1749. One °f the moll interelling performances which 
M. de Lille publilhed relative to geography, was his “New 
Charts of the Difcovedes of Admiral de Fonte, or F uente, 
made in 1640, and thofe of other Navigators, Spaniffi, 
Portuguefe, Engliffi, Dutch, French, and Ruffians, in the 
Northern Seas, with Explications, &c.” 1750 and 1753, 
4to. This work, and Louis de Lille's voyage with cap¬ 
tains Tchirikow and Beering on the wellern coalls of 
America, ferved mutually to illultrate and confirm each 
other, and gave to the charts of M. de Lille all the autho¬ 
rity poffible ; and they furnifhed M. Buache, fird geogra¬ 
pher to the king, with the materials for his Geographical 
and Phylical Confiderations, which he publifhed in 1752, 
and following years. At the time when aftronomers were 
impatiently waiting for the tranfit of Mercury over the Sun 
in 1753, M. de Lille fignalifed his zeal for the fervice of 
afionomy by publifiling a very curious map of the world, 
in which he reprefented the effect of the parallaxes of 
Mercury in different countries, in order to point out the 
proper places for making fuch obfervations on the tranfit 
as Ihould, from the difference of their refults, furnilh 
a method of determining the dillance of the Sun, in a 
manner fimilar to that applied by Halley to the tranfit of 
Venus. The tranfit of Mercury over the Sun in 1756, 
likewife, fully employed M. de Lille for a long time. 
This was the twelfth tranfit of that planet noticed by af¬ 
tronomers ; and was attended with tins particular advan¬ 
tage, that the apparent orbit traverled nearly the centre 
of the fun. This circumftance was made ufe of by M. de 
Lille, in determining the diameter of the fun. 
The lalt work of M. de Lille, inferted in the volumes 
of the French academy, is a memoir on the comet of 1758, 
which had been difcovered by a peafant in the neighbour¬ 
hood of Drefden on the 25th of July, and which Meffier 
found on the 15th of Augull, with the inftruments, and 
by following the method propofed by M. de Lille in the 
preceding year, for obferving the celebrated comet of 
Halley. The map of thefe obfervations was prefented 
by M. de Lille and M. Meffier to the king ; and the for¬ 
mer, who was received in the iugII gracious manner, had 
the honour of giving a particular explanation of it to his 
majefty. 
The comet of 1759, which had been predicted by Mr. 
Halley forty years before, afforded M. de Lille abundant 
fcope for the exercife of his fcientific Ikill. In the month 
of November, 1757, be began to publilh, in the Memoirs 
de Trevoux, a table of all the places in the heavens which 
were to be examined for this comet, on the fuppofitioa 
of its being difcernible, either thirty-five or twenty-five 
days before its perihelion, which he marked on a ce- 
leltial planifphere; and he conftrufted an inftrument, 
with the necefi'ary diviiions and conveniencies for eafily 
finding it, and marking its pofition as foon as'it ihould 
be difcovered. • Thefe preparations he confided to M. Mef¬ 
fier, an able obferver, who was chofen by M. de Lifle, 
with the confent of the minilter, to affilt him in his la¬ 
bours. M. Meffier fearched for the comet during a year 
and a half, and in that time oblerved for feveral months the 
comet of 1758. At length, on the 2ilt of January, 1759, 
he difcovered the long-fought-for comet of Halley, and al- 
certained its place. M. de Lille gave an account to the 
public of thefe firlt obfervations on that comet, in the fir It 
volume of the Mercure for July 1759; but be referved 
the 
