790 LIS 
the fun with great care, and was led to form the idea of 
a theory to determine their motions, and by that means 
to calculate the fun’s rotation on his axis. In the year 
1710, he delivered in a propofal to the academy for afcer- 
tainir.g in France the figure of the earth ; and fome years 
afterwards his defigns relative to that object were carried < 
into execution. In 1723, he gave in a curious memoir on 
the tranfits of Mercury, in which he propofed a new me¬ 
thod for calculating them, obferving them, and drawing 
conclufions from them. He was the firft who obferved 
that, in order to calculate the tranfits of Mercury and 
Venus over the Sun, it is not neceflary to have their geo¬ 
centric longitudes, that is, their longitudes as feen from 
the Earth, but that it is Sufficient to calculate their lon¬ 
gitudes as feen from the Sun. He alfo propofed the ufe 
of the quadrant in obferving thefe tranfits, which is in 
various refpefts better adapted to the purpofe than any 
other inftrument; and in this he has been followed by the 
jnoft able aftronomers. 
In the year 1724, M. de Li fie paid a vilit to England, 
where he was honoured with the acquaintance and efteem 
of Newton and Halley. The firft made him a prefent of 
his portrait; and the fecond gave him a copy of his aftro- 
nomical tables, which he had printed in the year 1719, but 
which were not publifhed before the year 1749. In this 
country, he was admitted a fellow of the Royal Society ; 
and before his death he held a fimilar connexion with all 
the great fcientific academies in Europe. 
The year 1726 prefents us with one of the moft remark¬ 
able events in M. de Lille’s life, his tranfplantation from 
his native country into Ruflia. So long ago as the year 
1721, he had received a letter from M. Blumentroft con¬ 
taining an invitation from Peter the Great, to go to Pe- 
terlburg, and fill the poll of aftronomer in the Imperial 
Academy of Sciences. Four years he deliberated on this 
offer, when the death of that monarch feemed to termi¬ 
nate all negotiation for his removal to the north. But 
the emprefs Catharine, who fucceeded to the throne after 
the death of Peter, and was determined to carry on his 
plans for the civilization of his barbarous countrymen, 
did not forget that on his dying bed he ftrongly advifed 
her to invite learned foreigners into the country, and to 
protect them. Accordingly, fhe renewed the invitation 
of that monarch to M. de Lille, with the promife of a 
confiderable penfion. At length he determined to accept 
of the invitation ; and, having received the king's licence 
for himfelf, his brother Louis, and M. Vignon, who were 
to afiift him in his labours, he let out with his compa¬ 
nions for Peterfburg in the year 1726. During the pro- 
grefs of his journey, his zeal for the improvement of fci¬ 
ence induced him to make a Ihort ftay at Rodeftein in 
Thuringia, at Berlin, and at Dorpt in Livonia; at each 
of which places he made the obfervations neceflary for 
determining their longitudes and latitudes. On his arri¬ 
val at Peterfburg in the month of October, he was efta- 
blifhed in the houfe of the obfervatory built by Peter the 
Great, which he occupied nearly twenty-one years, fpent 
in inceflant labours for the improvement of aftronomy and 
geography. This obfervatory was fpacious and commo¬ 
dious j but it was deficient in many neceflary inftruments 
for fuch an inftitution, which he endeavoured, without 
fuccefs, to obtain. He was obliged, therefore, to enter 
on his labours under great difadvantages, owing to the 
imperfection of his apparatus, which he endeavoured to 
remedy as much as poffible by the inftruments which he 
brought from France, and fuch others as by degrees he 
■was permitted to conftruch M. de Lille’s firft leries of 
obfervations were employed in afcertaining the longitude 
and latitude of Peterfburg, and the refractions in that 
northern region. Afterwards lie devoted feveral years to 
an afliduous obfervation of the meridional height of all 
the planets, and of the fixed ltars of the three firft mag¬ 
nitudes ; calculated to determine the politions of all thefe 
ftars, with their annual variations, and to eftablilh a va¬ 
riety of points neceflary to illuflrate the theory of the pla* 
L E« 
nets, and particularly that of the moon. To thefe were 
added, an immenfe number of obfervations out of the 
meridian ; eclipfes of the fun and moon ; occultations of 
the planets and of the fixed ftars by the moon ; and their 
approximations and conjunctions, which he noticed with 
the utmoft poffible exaCtnefs. He, likewife, from the 
aftronomical and phyfical obfervations made by his bro¬ 
ther in his expedition to Siberia, calculated the longi¬ 
tudes of a vaft variety of places, which he compared with 
thofe of the Jefuits in China, whom he engaged to make 
obfervations correfpondent to thofe of his brother. But 
thefe obfervations, fo ufeful to the geography of that part 
of Afia, remain yet in manufeript, excepting a few, pub- 
liibed in the firft volume of the Memoirs of M. de Lifle,, 
and in the Memoirs of the Academy of Peterlburg. 
As in the year 1740 a tranfit of Mercury over the Sun 
was expefted which would not be vifible in Europe, the 
zeal of M. de Lille in the caufe of fcience determined him 
to encounter the hardlhips and dangers attending a viiit 
to diftant Afiatic regions, that he might have an oppor¬ 
tunity of obferving it. With this defign he quitted Pe¬ 
terlburg in the month of February, and, after undergoing 
immenfe fatigue, penetrated over the fnow and ice into 
thedeferts of Siberia. His firft obfervations in this terrible 
climate were on the intenfenefs of the cold, which was. 
greater than had ever been pointed out by a thermometer, 
or than it was conceived poffible for human nature to l'uf- 
tain. A memoir of M. de Lifle on this fubjeCt is inferted 
in the volume of the French Academy for 1749. But, 
when the time for obferving the tranfit arrived, after all his 
fatigues and fufferings, his philofophy was put to the fe¬ 
vered: trial by the cloudinefs of the day, which totally fruf- 
trated the defign of his journey. To indemnify himfelf 
as far as was pofiible for this grievous mortification, he 
employed his time in making geographical and phyfical 
obfervations, and in drawing up a defeription of the coun¬ 
try, which is inferted in the eighteenth volume of Quer- 
lon’s Hiftory of Travels, &c. Geography was indeed one 
of the grand objects of his labours, and was particularly- 
recommended to him by M. de Maurepas, when he con¬ 
tented to his departure from France. Accordingly, 
during the firft months of his fettlement at Peterlburg, he 
formed a plan for making a general map of Ruflia, and pro¬ 
cured the eftablifhment of a board of geography. He then 
obtained particular maps of the provinces of this vaft em¬ 
pire, with the names and accompanying obfervations tranf- 
lated into French} and, as he became foon diflatisfied 
with the flownefs of the interpreters afligned him, he 
learned to read them in the Ruffian language, and to trans¬ 
late them himfelf. He particularly required that aftrono¬ 
mical obfervations Ihould be made in the moft diftant. 
parts of the empire. For this purpofe his brother Louis 
was commiflioned, in 1737, to commence fuch obferva¬ 
tions in the government of Archangel, and to proceed as 
far as Kola; on which expedition he Spent nearly three 
years. But in his geographical as well as aftronomical 
department, M. de Lille met with numerous obftacles and 
discouragements which greatly impeded his progreSs; and 
he was reduced to no Small difficulties, by the delays of 
the payments of the academy, and the arrears of his pen¬ 
sion. Befides the labours of his brother, M. de Lifle was 
furnilhed with the communications of thirty young Ruf¬ 
fians, who were particularly inftrubled by two able Eng- 
lilh profelfors in the art of Surveying and drawing maps, 
and Sent to the different provinces of the empire for that 
purpofe. Thefe maps were delivered to M. de Lille, who 
perfonally examined thefe young geodejifls, as Lalande calls 
them, on their return to Peterlburg, alking from them 
particulars of the countries which they had refpe&ively 
Surveyed, to the minuteft detail, without omitting the 
fmalleft village or the fmalleft ftream ; that he might thus 
fupply as far as poflible what their want of fcience and 
proper inftruments prevented them from performing, and 
unite their Scattered members in one regular whole. Ha 
alfo obtained an order from the cabinet of the emprefs 
3 Catharine 
