PINGRE. 
464 
and was furnifhed by the abbot and chapter with a fix-foot 
telefcope, while he had the loan of an excellent quadrant 
from the academy. Having foon become acquainted with 
Le Monnier, whofezeal foraftronomy led him to embrace 
every opportunity of making profelytes to that fcience, 
Pingre was induced by him to diftinguiffi himfelf by an 
undertaking as difficult and laborious as any in which 
an aftronomer could engage; that was the calculation of 
a Nautical Almanac, to enable navigators more eafily to 
afcertain the longitude by means of lunar obfervations. 
At the folicitation of the authors of The Art of verifying 
Dates, lie calculated a Table of the Eclipfes of the Sun 
and Moon from the commencement of the Chriftian sera 
to the year 1900; and afterwards a Table of the Eclipfes 
vifible from the Northern Pole to the Equator, for a 
thoufand years before our aera. The utility of thefe 
labours for verifying hiftorical dates, marked by the 
appearance of thefe phenomena, induced the Academy of 
Tnfcriptions to infert a part of them in the forty-fecond 
volume of their Memoirs. He publiffied “ The State of 
the Heavens for 175+;” in which the moon’s place was 
calculated with the utmoft exaftnefs according to the 
tables of Halley, for noon and midnight, with the right 
afcenfion in feconds of time twice a-day. Afterwards he 
publiffied limilar works for the years 1755, 1756, and 
1757. In 1756 he was received a free afTociate of the 
Academy of Sciences; .and in the following year he 
entered apon a new career, which he purfued with the 
higheft diftin&ion, that of calculating the revolutions of 
comets. That he alone calculated more orbits of comets 
than all the aftronomers together in an equal fpace of 
time, was fufficiently proved by the immenfe work which 
he afterwards publiffied on the hiftory and theory of 
thefe eccentric bodies. In the year 1758, he publiffied 
“ A Memoir relating to the Difcoveries made in the 
South Sea, during the laft Voyages of the Engliffi and 
French round the World,” in 4to. 
Our countryman Dr. Halley having aflerted, that the 
tranfit of Venus over the fun’s difk in 1761 would prove 
of the utmoft ufe in ascertaining the precife horizontal 
parallax of the fun ; when that year was approaching, 
the different Scientific bodies in Europe became ferioufly 
intent on the means of deriving from that phenomena as 
much advantage as poffible to aftronomy. With this 
view the French Academy, fanftioned and encouraged 
by government, among the places moft proper for observ¬ 
ing the tranfit,* fixed upon the Small ifland of Rodriguez 
in the Indian Ocean, beyond the Ifles of France and 
Bourbon, and in nearly twenty degrees of fouthern lati¬ 
tude. This ifland had then no inhabitants, excepting 
twenty negroes under the command of an officer, who 
kept poffeffion of it on account of its being frequented 
by veflels from the Ifles of France and Bourbon, for fup- 
plies of the land-tortoife with which it abounded. The 
principal reafon for fixing upon this fpot was the confider- 
ation, that, acccording to the calculations of Caffini de 
Thury and others, the whole tranfit of Venus over the 
fun’s difk would be there viSble, as her interior contaft 
on her entrance upon it would take place about half an 
hour after fun-rife. When the place of obferver was 
offered to Pingre, be accepted of it with the utmoft fatif- 
fa&ion, undaunted by the profpeft of the fatigues and 
perils to which fuch an undertaking muft neceflarily 
expofe him. He did not even afk for an afliftant in his 
labours; but the Academy took care to prevent the ne- 
ceffity of fuch an application, by obtaining leave from the 
miniftry that Thuilier, who had for Some time been en¬ 
gaged in making aftronomical obfervations, ffiould ac¬ 
company him in that capacity. Pingre left France in 
the autumn of 1760, and on the 6th of June 1761 made 
his obfervations. He was unfortunately prevented by 
the badnefs of the weather from feeing the entrance of 
the planet on the fun’s difk, but thought himfelf war¬ 
ranted in concluding from his fubfequent obfervations, 
that the parallax of the fun was io'^z. At the fame time. 
the Engliffi aftronomer Mr. Mafon concluded from the 
obfervations which he made at the Cape of Good Hope, 
that the parallax was 8"'2. La Lande, in his Aftronomy, 
publiffied in 1764, adopted a medium between thefe con- 
clufions ,fuppofmg the parallax to be 9"; in which he was 
followed by aftronomers in general, till more numerous 
obfervations made on the tranfit of 1769, led to a different 
refult. 
After the return of Pingre from the Eaft, he publiffied 
“ A Defcription of Pekin,” to accompany a plan of that 
city engraved by Jofeph De Lifle ; in which he ffiowed 
the pofition of that capital from the refult of a number of 
calculations of eclipfes, and afcertained its longitude, by 
other calculations, with a degree of precifion to which 
none of the labours of the fcientific miffionaries had any 
pretenfions. In 1767, he accompanied the marquis de 
Courtanvaux on a voyage to Holland, on-board the 
Aurora corvette, for the purpofe of determining the accu¬ 
racy of the marine time-pieces of Le-roy. Two years 
afterwards he failed for the ifland of St. Domingo in the 
Weft Indies, on-board the Ids man of war, to make trial 
of Berthoud’s time-pieces, and to obferve the laft tranfit 
of Venus in 1769. To this phenomenon the attention 
of all the fcientific academies in Europe was anxioufly 
direfled, and confiderable preparations were made for 
obferving it by thofe of England, France, Ruffia, and 
Denmark, under the patronage of their refpeftive fove- 
reigns, who fent able aftronomers to different places in 
the old and new worlds, where it might be viewed to the 
greateft advantage. La Lande was originally intended 
to be fent on this million to St. Domingo; but, as his 
various engagements would not permit him to leave 
France, Pingre was fubftituted in his room, and performed 
the fervice expected from him in the moft able and fatif- 
fadlory manner. An account of this voyage, which 
proved of confiderable importance to the fcience of geo¬ 
graphy, as well as to aftronomy, appeared in 1773, in 2 
vols. 4to. After comparing the refults of the immenfe 
number of calculations made by the obfervers of this 
tranfit of 1769, it has been thought reafonable to conclude 
with La Lande, that the fun’s mean horizontal parallax 
may be ftated at Z"’G. In the year 1771, Pingre made 
another voyage, on-board the Flora frigate, with the view 
of rendering further fervice to the interefts of geographi¬ 
cal and aftronomical fcience. He had for a companion 
in this voyage the chevalier de Borda, a celebrated engi¬ 
neer and geometrician ; but the account of their proceed¬ 
ings and experiments, which was publiffied in 1778, in 
2 vols. 4to. is almoft entirely the work of Pingre. 
In 1784, our author publiffied his “ Cometography, or 
Hiftorical and Theoretical Treatife on Comets,” in 2 
vols. 4to. which is the moft confiderable of his perform¬ 
ances, and contains calculations of the orbits of all the 
comets of which any account has been preferved. La 
Lande, after obferving that it is the only complete trea¬ 
tife with which we are furnifhed relating to this branch 
of aftronomy, pays the author the compliment of faying, 
that it would be a very difficult tafk to draw up a work 
upon the fame fubjefft that ffiould excel it. In 1786, 
Pingre gave to the public a French tranflation of the 
Aftronomicon of Manilius, after Bentley’s edition of that 
work, in 2 vols. 8vo. to which he added a French verfion 
of the celebrated poem of Aratus, and the lives of the 
other Latin poets who have written concerning the 
courfe of the ftars. So early as the year 1756, our author 
had announced his intention of writing the Hiftory of 
the Aftronomy of the 17th Century. This work Le 
Monnier engaged him to undertake, and communicated 
to him the manufcripts of Boulliau ; to which Pingre 
himfelf made valuable additions, from the collections of 
other eminent men of fcience. His attention to this 
work, however, was neceflarily interrupted by the va¬ 
rious engagements and labours of which we have already 
given an account; fo that he could not fpare the time 
requifite for proceeding regularly with it, before the year 
1786, 
