S 84 H A L 
-jefty with a valuable diamond ring, taken from his own 
■linger. He was likewi'fe treated with great refpect by 
the king of the Romans, prince Eugene, and the princ i¬ 
pal officers of the imperial court. Not long alter his 
■return to England, he was fent a fecond time on the 
fame bufinefs; and, palling through Hanover, he had 
the honour of being entertained by the electoral prince, 
afterwards Gebrge 1. of' England, and his lifter, the 
•queen of Pruffia. Upon his arrival at Vienna, he was 
again prefented to the emperor, who gave immediate or¬ 
ders to his chief engineerto attend him tolftria, whither 
they repaired, and added fome new fortifications to the 
port of Triefte, and afcertained the capacity of that of 
Boccari-for receiving all kinds of fhipping with falety. 
■Captain Halley returned toJEngland in November 1703, 
when he was appointed Savilian profeflor of geometry at 
• Oxford, in the room of Dr. Wallis, deceafed; upon 
which promotion he was honoured by the univerfity 
with the degree of doCtor of laws. Scarcely was he let- 
tied in his new office, when he undertook to complete a 
tranflation, from the Arabic into Batin, ot, Apollonius <le 
.SeElione Rationis, which had been begun by Dr. Edward 
Bernard, but laid alide before he had gone through the 
tenth part of it. The original Greek of this treatile was 
no longer in exiftence, and this Arabic manufcript was 
•the only verfion.extant; but it lay under the difadvan- 
tage of being very ill written, incorrect, and in a muti¬ 
lated (fate : which circumftances probably difcouraged 
Dr. Bernard from proceeding with his tranflation. Up¬ 
on being lhewn a fair copy of what lie had executed, 
Dr. Halley immediately refolved to complete it, not- 
withftandmg the great difficulty of the talk, more efpe- 
cially to him who, at that time, was entirely unacquaint¬ 
ed witli the Arabic language. The method which lie 
took was, firft, to obferve carefully the lenfe of all fucli 
words in the original as Dr. Bernard’s verfion furniflied ; 
and then, being a perfect tnafter of the fubjeft of the 
treatife, and. confidering well the argument of Apollo¬ 
nius, he began, by degrees, to difcover the fenfe ot the 
reft. Proceeding in this way ot deciphering, he read 
the whole book through, and in a manner underftood 
it; fo that by a fecond perufal he was enabled, without 
the aid of any other perfon, to bring it into the form in 
which it now appears. At the fame time, trom the ac¬ 
count which is given of them by Pappus, he reftored 
the two books by the fame author, which are loft, De 
Settione Spatii-, and the whole work was publiflied by 
him at Oxford in 1 vol. 8vo. 1706. 
No fooner was this laborious talk completed, than he 
engaged, conjointly with Dr. David Gregory, in pre- 
- paring for the prefs, Apollonius’s Conics, and he ven¬ 
tured to fupply the whole eighth book of the original, 
which is loft. Here he had again the Lemmata of Pap¬ 
pus, Hill extant, to affift him. Thefe ftiowed the con¬ 
nection between the feventh book and the eighth, and 
by that help he entirely fupplied it. In this perform¬ 
ance the elegant tafte and manner of Apollonius are fo 
perfeftly copied, that the belt judges have been of opi¬ 
nion, that the whole eighth book, as publiflied by Dr. 
Halley, might very well pafs for the work of the fame 
Grecian mailer. To this work he added the treatife of 
Serenus on the Sedtion of the Cylinder and Cone, print¬ 
ed from the original Greek, with a Latin tranflation, in 
two books, and publiflied 111,1710, in folio. Befides 
thefe, the Mifcellanea Curiofa, in 3 vols.Svo. containing 
fome original pieces of his own, were printed under his 
direction, and made their appearance in 170S. In 1713, 
Dr. Halley fucceeded fir Hans Sloane in the office of 
fecretary to the Royal.Society; and upon the death of 
Mr. Flamfteed, in 1719, be was appointed to fucceed 
him at Greenwich as aftronomer-royal, by George I. 
Two years afterwards he refigned his fituation of fecre¬ 
tary to the Royal Society, that he might purfue with 
lefs interruption the ftudies peculiarly appropriate to 
his new appointment, and particularly his favourite ob- 
H A L 
jedt of completing'the theory*of the moon’s motion; - 
To this defign he devoted his utmoft afliehiity; and, al¬ 
though he was in the fixty-fourth year of his age when 
he entered, upon his office at Greenwich, yet for the 
fpace of eighteen years he watched the heavens with 
theclofeft attention, fcarcely miffing a meridian view of 
the moon during all that time, when the weather was 
not unfavourable, and performing the.whole bufinefs o'f 
the obfervatory without any affiftant. 
Upon the acceflion of George II. his conforl, queen 
Caroline, who took pleafure in patronifing men of ta¬ 
lents, paid a vifit to the royal obfervatory ; and, being- 
gratified with the reception which flie met with, took 
notice that Dr. Halley had formerly ferved the crown 
as a captain in the navy. Soon after this vifit flie ob¬ 
tained for him a grant of his half-pay for that commif- 
lion, which he enjoyed during the remainder of his life. 
He was alfo offered the appointment of mathematical 
preceptor to the duke of Cumberland ; but he declined 
the acceptance of-it', both on account of his advanced 
age, and becaufe the neceffary attendance upon that 
employment would interfere too much with his duty at 
Greenwich. In Auguft, 1729, he was admitted a fo¬ 
reign member of the Academy of Sciences at Paris. He 
had enjoyed an uninterrupted ftateofgood health amidft 
his laborious avocations till the year 1737, when a pa¬ 
ralytic attack on his right hand evinced the decay of his 
conftitution. He died in his chair, without a groan, 
on the 4th of January, 1741-2, in the eighty-fixth year 
of his age. Dr. Halley was naturally of an ardent and 
glowing temper, of a generous and friendly difpofition, 
open and punctual in all his tranfaCIions, candid in his 
judgment, uniform and blamelefs in his manners, of an 
amiable affability, always communicative, and totally 
difinterefted. He lived and died in that mediocrity fo 
much extolled by the beft philofophers; the free choice 
of which implies.a great degree both of wifdom and of 
virtue. His great qualifications were tempered with a 
vein of gaiety and good humour, which neither his ab- 
ftraCted fpeculations, the infirmities of old age, nor the 
palfy itfelf, were able to impair. And, together with 
this happy cheerfulnefsof temper, his memory and judg. 
ment were preferved to the laft. Befides the articles 
noticed above, he was the author of, r. Tabula AJlrono- 
mica, &c. which was publiflied after his death, in 1752, in 
4to. with this title, Aftronomical Tables, with Precepts, 
both in Englifli and Latin, for computing the Places of 
the Sun, Moon, Planets-, and Comets. 2. A Synopfis 
of the Aftronomy of Comets, annexed to the fecond vo¬ 
lume of Dr. Gregory’s Elements of Aftronomy; and a 
vaft multitude of papers in the Philofophical Tranfac- 
tions, vol. xi. to vol. lx. 
HAL'LIA,yi in botany, a genus of the clafs diadel- 
phia, order decandria. Effential generic characters— 
Calyx five-parted, regular; legume one-feeded, two- 
valved. 
Species. 1. Hallia alata: leaves oblong, glabrous; 
ftipules decurrent ; Item winged. 2. Hallia flaccida : 
leaves lanceolate, mucronate, glabrous: peduncles one- 
flowered, as long as the leaves. 3. Hallia virgata : 
leaves lanceolate, mucronate, glabrous : peduncles one- 
flowered, fhorter than the leaves. 4. Hallia cordata: 
leaves hearted, oblong, acute, glabrous: peduncles one- 
flo.wered, as long as the leaves.. 5. Hallia afarina : 
leaves hearted, roundifh, mucronate, villous: pedun¬ 
cles one-flowered, as long as the leaves. Thefe five in¬ 
habit the Cape. 
6. Hallia hirta : leaves hearted, roundifh, ciliate: 
flowers nearly feffile ; Item without ftipules. Leaves 
with pellucid dots; flowers yellow. Inhabits Tran- 
quebar. 
7. Hallia imbricata : leaves heart-ovate, convolute, 
imbricate : flowers axillary, feffile. Leaves ciliate on 
the margin and midrib. Inhabits the Cape. 
S. Halliafororia: leaves roundifh kidney-form, emar- 
ginate, 
