U2 HAL 
8vo. In 1736 he publifhed a treatise entitled, The 
Truth and Importance of the Scripture Dodlrine of the 
Trinityand Incarnation demonftrated ; and when, in the 
year 1737, Dr. Morgan commenced his infidious attack 
upon revealed religion, by the publication of. The Mo¬ 
ral Philofopher, Mr. Hallet was one of the firft who en¬ 
tered the lifts againft him, and fuccefsfully expofed his 
fophiftry and mifreprefentations. In 1738, .he under¬ 
took the defence of revelation againft'another difinge- 
nuous attempt to fubvcrt it, by publiftiing, The Con¬ 
fident Chriftian. He died in 1744, when about fifty-two 
years of age. That he pofletl'ed a very confiderable 
fhare of learning, combined with great critical fagacity, 
is abundantly proved by Ivrs publications, and particularly 
by his three volumes of Notes arid Difcourfes, which are 
deferVedly held in high eftimation by biblical ftudents. 
As a minifter he difcharged the duties of his profeflion 
with exemplary, diligence and fidelity ; and in private 
life, lie fecured the efteem of all who knew him, by the 
mildnefs and gentlenefs of his temper, and his truly 
.Chriftian behaviour, 
HAL'LET’s FORT, a fort of the ifland of Barba- 
does: one mile and a quarter north-north-weft of Bridge¬ 
town. 
HAL'LEy (Edmund), an eminent Englilh mathema¬ 
tician, born in the pariih of St. Leonard, London,' in 
1656. He was early placed at St. Paul’s fchool, under 
the care of Dr. Gale ; where he not only diftinguilhed 
himfelf by his proficiency in claftical learning, but made 
confiderable advances in mathematical knowledge. In 
1673, he was entered a commoner of Queen’s-college, 
Oxford, where he applied himfelf chiefly to mathema¬ 
tics and aftronOmy. Cf his {kill in aftronomy; he gave 
a Angular proof when lie was only nineteen years of 
age, by communicating to the world his DireCt and Geo¬ 
metrical Method of finding the Aphelia and Excentri- 
city of the Planets. He likewife diftinguilhed himfelf 
by the improvement which he made in other parts of 
aftronomy. Befides fome curious obfervations on an 
eclipfe of the moon, June 17, 1673, he made fome dif- 
cyveries refpeCting a fpot in the fun, feen at Oxford in 
July and Auguft 1676, by which t-he motion of the fun 
round its own axis, a phenomenon till then not tho¬ 
roughly afcertained, was fatisfa&orily determined. 
During the fame year he noticed an occupation of Mars 
by the moon, which he afterwards made ufe of, with 
others, in fettling the longitude of the Cape of Good 
Hape, againft the objections of the French aftronomers. 
While at Oxford, - he likewife obferved the motions of 
Jupiter and Saturn; and was thus enabled to introduce 
feveral corrections into the belt aftronomical tables of 
thofe planets then extant; and he difcovered the me¬ 
thod.ef conftruCting eclipfes of the fun, by means of 
which the calculation of parallaxes in thofe phaenomena 
was fuperfeded. 
But Mr. Halley’s labours at Oxford had not been con¬ 
fined to the objects already mentioned. From his firft 
admiflion to college he had been careful to make the 
proper obfervations for afcertaining the true places of 
the fixed ftars, in order tocorreft the errors of Tycho 
Brahe. His original view in this was, to carry on the 
defign of that firft reftorer of aftronomy, by completing 
the catalogue of thofe ftars from his own obfervations. 
While the celebrated aftronomers Hevelios and Flam- 
fteea were engaged in afcertaining the true places of the 
fixed ftars in'the catalogue of Tycho Brahe, Mr. Hal¬ 
ley adopted a new' and arduous purfuit, which was to 
perfect the whole fcheme of the heavens, by the addi¬ 
tion of the ftars which lie fo near the fouth pole, that 
they could riot be obferved by either of thofe aftrono¬ 
mers, as never rifing above the horizon either at Dant- 
zic, or at Greenwich. He made his intention known to 
fir Jofeph Williamfon, then fecretary of ftate, who high¬ 
ly applauded his purpofe, and communicated it to 
Charles 11. His maje-fty was fo pleafed with his dCfign, 
HAL 
that he granted him a letter of recommendation to the 
Eaft-India Company, who engaged to fupply him with 
all the accommodations and conveniences in their power, 
and to convey him to the ifland of, St. Helena,' which he 
fixed upon as a fituation proper for the accomplifhment 
of his defign. He embarked for that ifland in Novem¬ 
ber 1676, when he was only twenty years of age, and ar- v 
rived there after a voyage of three months. He applied 
with unceafing diligence to the ufe of his telefcopes till 
he had finifhed the talk which he had undertaken, and 
entirely completed his catalogue. Upon, his return to 
England, in November 1678, after an abfence of two 
years, he delineated a planifphere, in which he accu¬ 
rately laid down the exaCt places of all the ftars near 
the fouth pole, from his own obfervations. The king 
expreffed himfelf greatly fatisfied with Mr. Halley’s 
exertions-, and, at his requeft, granted him a letter of 
mandamus to the univerfity of Oxford, for the degree of 
M. A. which was dated November 18, 1678 ; and in the 
fame month he was defied a fellow of the Royal Society. 
In 1679, he publilhed his catalogue, under the title of, Ciz- 
ta/ogus Stellarum Auflralium, five Supplementum Catalogi Tycho- 
nici, exhibens Longitu dines & Latitudines Stellarum fixarum qute 
prope Polum antarclicum files in Horizonte Uranaburgico Tyrhoni 
inconfpicua fuere, &c. Accedit Appendicula de Rebus quibufidam 
afironomicis Notatu non indignis. The articles in the Ap¬ 
pendix confift of an account of the tranfit of Mercury 
over the fun’s dife in 1677, with methods for finding the 
folar and lunar parallaxes, and obfervations ufeful for 
correfting the theory of the moon. This work was 
fcarcely publifhed, when Mr. Halley was fixed upon by 
the Royal Society to go to Dantzic, for the purpofe 
of endeavouring to adjuft a difpute between Hevelius 
and Mr. Hooke, concerning the preference's to plain 
or dioptric fights in aftrofcopical inftruments. He ar¬ 
rived at that city in May 1679, and immediately en¬ 
tered upon aftronomical obfervations in conjunction with 
Mr. Hevelius, which were clofely continued by them 
till the 18th of July, when Mr. Halley returned to Eng¬ 
land,. Before he fet out, he wrote a letter to Mr. He¬ 
velius, in which he acknowledged, in the ftrongeft terms, 
the furprifing accuracy of that aftronomer’s obferva¬ 
tions, and voluntarily offered himfelf as awitnefs of the 
fcarcely credible certainty of his inftruments, againft any 
who fhould call that matter in queftion. In 1680 Mr® 
Halley again quitted his native country, to undertake 
what is commonly called the grand tour , in company 
with his friend the celebrated Mr. Nell'on. While they 
were on the road from Calais to Paris, Mr. Halley had, 
firft of any one, a fight of the remarkable comet of that 
year, as it appeared for the fecond time, in its return from 
the fun. He had before feen this-grand phenomenon in 
itsdefeent, and he now haftened to complete his obferva¬ 
tions upon it, by viewing it from the royal obfervatory 
of France. His defign in this part of his tour was to efta- 
blifh a friendly correfpondence betiveen the aftronomers- 
royal of Greenwich and Paris; and at the fame time to 
embrace the opportunity of improving himfelf under fa 
great a mafter as Cafiini. From Paris he went to Italy, 
where he'fpent a great part of the year 1681; but, his 
affairs requiring his prefence at home, he left his fellow- 
traveller at Rome, and returned to England. 
In 1682 Mr. Halley married a daughter of Mr. Tooke, 
auditor of the exchequer; and took a hoiife at Ifling- 
ton, where he immediately fet up 'his apparatus, and 
applied himfelf with (he utnvoft afliduity to his favou¬ 
rite ftu'dy. In the following year he publifhed his The¬ 
ory of the Variation of the Magnetical Compafs; in 
which he fuppofes the whole globe of the earth to be 
oiie great magnet, having four magnetical poles or points 
of attraction. During the fame year likewife, he enter¬ 
ed upon a new method of finding out the longitude by 
accurate obfervations of the moon’s motion, the idea of 
which had early fuggefted itfelf to his mind. In 1684, 
lie turned his thoughts to the fubjeCt of Kepler’s fefqui- 
