-H A R 
elected one of its fellows. Being originally intended 
for the church, his thoughts and ftudies were for fome 
time directed towards that objeCt : but upon a clofer 
confideration of the terms of clerical conformity, ferious 
fcruples arofe in his mind againft fubfcription to the 
thirty-nine articles of religion. Finding, therefore, that 
he could not enter into the fervice of the national efta- 
bliflinient without doing violence to his confcience, he 
determined to apply his talents and Itudies to the medi¬ 
cal profeftion ; in which he foon became eminent for 
(kill, integrity, and humanity. He firft began to prac- 
tife pliyfic at Newark, in Nottinghamthire ; whence he 
removed to Bury St. Edmund’s, in Suffolk. After this 
he fettled for fome time in London ; and finally went 
to live at Bath, where he fpent the remainder of his 
days. His ftudies were not confined folely to the fub- 
jedls connected with the medical profeflion, but compre¬ 
hended moft of the important branches of natural and 
moral fcience; and in his purfuit of them he was ani¬ 
mated by the concurrence and intimacy of fome of the 
njoft refpe.dtable and learned men of his age. From his 
earlieft youth he was devoted to the fciences ; particu¬ 
larly to logic and metaphyfics. He ftudied mathema¬ 
tics, together with natural and experimental philofo- 
phy, undef'the celebrated profefTor Saunderfon. After 
thus ftoring his mind with all the information he could 
obtain upon ph'yfiological fubjeCts, he prefented to the 
world, in' 174.9, l'' 3 valuable work, entitled, Obferva- 
tio'ns on Man, his Frame, hisDuty, and his Expectations, 
in two Parts, 2 vols. 8vo. The moft valuable edition of 
it was publithed in 1791, in 4to. with notes and addi¬ 
tions. to the fecond part, tranflated from the German of 
the Rev. Herman Andrew Piftorius ; with a fketch of 
the life and charaCter of the author, by his foil. Dr. 
Hartley lived about nine years after the publication of 
this work,' and died at Bath in 1757, at the age of fifty- 
two years. He is laid to have written in defence of in¬ 
oculation for the fmall-pox, againft the objections of 
Dr. Warren, of Bury St. Edmund’s; and fome papers 
of his are to be met with in the Philofdphical Tranfac- 
tions. He was principally iiifirumental in procuring for 
the empiric, Mrs. Stephens, the five thoufand pounds 
granted by parliament, for difcoyering the compotition 
of her medicine for the ftone. In 1738 he publiftied, 
Obfervations made on ten Perfons who have taken the 
Medicament of Mrs. Stephens, 8vo. which were fol¬ 
lowed in 1739, w hh his View of the prefent Evidence 
for and againft Mrs. Stephens’s Medicine as a Solvent 
for the Stone, containing one Hundred and fifty-five 
Cafes, with fome Experiments and Obfervations, 8vo, 
and a Supplement to the View of the prefent Evidence, 
See. 8vo. His own cafe is the 123d in the above-men¬ 
tioned View ; b'ut notwithftanding any temporary relief 
which he might receive from the medicine, he is laid to 
liave died of the ftone, after having taken above two 
hundred pounds weight of foap-, which is the principal 
ingredient in its compofition. 
HART'MANN (John Adolphus), a learned German 
profefior of hiftory, born at Munfter, in 1680. As his 
parents were catholics, lie was educated in the fociety 
of'the Jefuits. In 1713 he renounced the papal com¬ 
munion, and united himfelf to the Calvinifts at Caflel. 
In 1722 he was created profefTor of hiftory and eloquence 
at Marpurg, at which place he died in 1744. The moft 
efteemed of his works are, 1. Hejloria Hajfiaca, 3 vols. 
2. Vitts- Pontijicum Romanorum Vittoris III. Urbani II. Paf- 
chalis II. Gelajii II. Calijli II. Honorii II. 3. The State of 
Sciences in Heffe. 4. Pracepta Eloquentia Rationalis, &c. 
Befides his larger works, hepublilhed more than eighty 
academic diftertations. 
HART'MANN (George), a German mathematician 
who flourifhed in the fifteenth century. In 1 540 he in¬ 
vented what is called the artillery ftaff, baculus bombar- 
dicus, for the ufe of engineers. He was alfo the author 
Vol. IX. N0. 58X. 
H A R 241 
of a Treatife on PerfpeCtiye, of which Pafquier du Ha¬ 
mel publiftied an improved edition at Paris, in 1336, 4to. 
HARTO'GIA, f. [in memory of Hartog, a Dutch 
gardener, and a celebrated traveller to the Cape of Good 
Hope.] In botany, a genus of the clafs tetrandria, order 
monogynia, natural order of duipofae, (rhamni, 7 v^.) The 
generic characters are—Calyx : perianthium five-cleft, 
hnootli, permanent: clefts acute, very ftiort. Corolla r 
petals four, ovate, obtufe, fpreading. Stamina : fila¬ 
ments four, very ftiort, inferted into the bafe of the 
germ; anthers gvate furrowed. Piftilfum : germ fu- 
perior, ovate, fmooth ; ftyle Ample, fubulate ; ftigma 
acute. Pericarpium: drupe juicelefs, ovate, fmooth, 
or a little roughifli, (fcarccdy as big as a bafel nut.) 
Seed : nut with two feeds, fomewhat flefliy .—EJJcntiul 
Charatter. Calyx, five-cleft; petals, four, fpreading; 
drupe ovate', inclofing two feeds. 
Hartogia Capenfis, a Angle fpecies. It is a tree, with 
oblong, ferrate, blunt, fmooth leaves. The flowers are 
axillary, minute, peduncled. Thunberg difeovered it 
in the woods near, the Cape of Good Hope. 
IIARTS'HORN, f. A volatile alkali, obtained by^ 
diliillation from the horns of animals ; for particulars of 
which fee the article Chemistry, vol. iv. p. 227. 
HARTSOE'KER (Nicholas), an eminent mathema¬ 
tician, born at Gouda in Holland, in 1-656. He devoted 
the earlier part of his life to the ftudy of the belles-let¬ 
tres, the Greek language, philofophy, and anatomy, un¬ 
der the ableft profeffors at Leyden and Amfterdam. His 
mafters in philofophy being all Cartefians, Hartfoeker 
efpoufed the fame caufe : but lie afterwards, thought 
proper to alter his opinion. While at Amfterdam, in 
1677, he began a courfe of microfcopical obfervations; 
which led him to the conltruclion of optical glafles, in 
which he very much excelled. With thefe acquire¬ 
ments he went to. France; and obferving that the tele- 
foopical glafles of the obfervatory at Paris were too 
fmall, however excellent in other refpeCts, lie foon made 
one larger, which he carried to M. Callini. Encou¬ 
raged by the favourable opinion of that eminent mathe¬ 
matician, he began to conftruCt glafles of all Lizes, and, 
at length, one of fix hundred feet focus, which, on ac¬ 
count of its rarity, he never would part with. While 
lie was at Paris, he publiftied, in 1694, An Elfay on Di¬ 
optrics, 4to. containing a perfpicuous demonftration of 
the whole theory of that fcience. Encouraged by its 
fuccefs, in 1696 he publiftied his Principles of Natural 
Philofophy, 4to. In confequence of thefe works, on the 
revival of the Royal Academy of Sciences at Paris, in 
1699, he was nominated a foreign aflociate ; and foon 
afterwards was chofen a member of the Royal Society, 
at Berlin. In 1704, after three years folicitation by the 
eleCtor palatine, Mr. Hartfoeker repaired to the court 
of that prince, by whom he was appointed honorary 
profeflbr of philofophy in the univerfity of Heidelberg. 
In the year's 1707 and 1708, he publiftied, in 2 vds. 4to. 
tile lectures he had given in that univerfity, under the 
title of Phyfical Conjectures. After the publication of 
thefe volumes, he.fet out on a vifit to the learned in 
other parts of Germany, and at Hefte^-Cadel was tempt¬ 
ed by liberal offers to enter into the fervice of the land¬ 
grave, but without effect. At Hanover he met with a 
gracious reception from the eleCtor, afterwards George 1 . 
of England. Upon his return to the court of the elec¬ 
tor palatine, that prince, who had heard of the burning- 
glafs conftruCted by M.Tfchirnhaufen, applied to Hart¬ 
foeker to make one of the fame kind; upon which he 
cauf'ed three to be caft in the glafs-houfe at Neuberg, 
and having foon finillied them, he prefented the eleCtor 
with the largeft of them, which was three feet and five 
inches (Rhineland meafure) in diameter, with a focus of 
nine feet. In 1710 he publiftied a volume entitled. 
Eclaircijfancnts fur les Conjectures Phyfiques , containing an- 
fwers to objections to his Phyfical Conjectures, moft of 
3 Q which 
