; A C H- 
to aVother perlon, not heretofore mentionefl, in thefe 
wor( js.(__“ As the.invention.has been claimed by M. Eu¬ 
ler,. M. Klingenftierna, and home other foreigners, we 
ought, for the honour'bf England, to aflert our right, and 
giv.q the merit of the difcovery to whom it is due; and, 
therefore* without farther .preface, I ill all obferve, that 
the inventor was Chefter More Hall, Efq. of More-hall, 
in-EfffX;)’,who, about 1729, as appears by-his papers, con- 
fitlering .the 'different humours of the eye; imagined they 
were -pkiced fo as to correct the different refrangibility of 
light. He then conceived, that if he could find fubftan- 
ces having .fuch properties as he fuppofed thefe humours 
might potfefs, he fliould be enabled to conftruCt an objebl 
glafs-that would fhew objefts colourlefs-. After many ex¬ 
periments he had the good fortune to find thofe properties 
in two different forts of glafs, and, making them difperfe 
the rays of light in. different directions, he fucceeded. 
About 1733- he completed .feveral achromatic object glaf- 
fes (though, .he did not give them this name) that bore an 
aperture of more than 2^.inches, though the focal length 
did not exceed,20 inches; one of which is.now in thepof- 
feilion of the.Rev. Mr. Smith, of Charlotte-ftreet, Rath- 
bone-place. This glafs has been examined by feveral 
gentlemen of eminence and fcientific abilities, and found 
to poffefs the properties of the prefent achromatic glades. 
Mr. Hall ufed to employ the working opticians to grind 
his lenfes; at the fame time he finifhed them with the ra¬ 
dii of the furfaces, not only to correct the different refran¬ 
gibility of rays, but alfo the aberration arifing from the 
fpherical figure of the lenfes. Old Mr. Bafs, who at that 
time lived in Bridewell iPrecinbl, was one of thefe working 
opticians, from whom Mr. Hall’s invention feems to have 
been obtained. 
In the trial at Weftininfter-hall about the patent for 
making achromatic telefcopes, Mr. Hall was allowed to 
be the inventor; but Lord Mansfield obferved, .“ It was 
not the perfon that locked up his invention in his ferutoire 
that ought to profit by a patent for fuch an invention, but 
he who brought it forth for the benefit of the public.” 
This, perhaps, might be faid with fome degree of juftice, 
as Mr. Hall was a gentleman of property, and did not 
look to any pecuniary advantage from his difcovery; and, 
confequently, it is very probable that he might not have 
an intention to make it generally known at that time. 
That Mr. Ayfcough, optician, in Ludgate-fireet, was 
in polfelfion of one of Mr. Hall’s achromatic telefcopes in 
1754, is a fact w hich at this time will not be difputed.” 
ACHTELING,/. a meafure for liquids ufed in Ger¬ 
many. Thirty-two acht dings make a heemcr ; four fciltims, 
or fciltins , make an achteling. 
ACHYR, a ftrong town and caftle of the L T kraine, fub- 
Jedt to the Ruffians fince 1667. It ftands on the river 
Uorlklo near the frontiers of Ruifia, 127 miles weft of 
Kiovv. Lat. 49.32. Ion. 36. o. 
ACHYRANTHES,/.. chaff, and ouiSn a flow¬ 
er.) In botany, a genus of the pentandriamonogynia clafs, 
and in the natural order of amaranthi. The generic cha- 
raftersare—Calyx : perianthium, outer three-leaved, lan¬ 
ceolate, acute, permanent; inner five-leaved, permanent. 
Corolla: none; neftary of five valves furrounding the 
germ, bearded at the tip, concave, caducous. Stamina: 
filamentsTiliform, the length of the corolla ; antherae ovate,, 
incumbent. Piftillum: germ fuperior, turbinate; ftyle 
filiform, the length of the ftamina ;. ftigma bifid, villous. 
Pericarpium: capfule roundifti, one-celied, not gaping. 
Seed: (ingle, oblong.— EJfential Char after. Calyx, five, 
leaved. Corolla, none. Stigma, bifid. Seed, folitary. 
Species. 1. Achyranthes afpera, or rough achyranthes : 
ftem fhrubby eredt: calyxes reflex, preffed to the fpike. 
The Sicilian plant grows near three feet high, with oblong 
pointed leaves; the flowers come out in long fpikes from 
the extremity of the branches. As foundAn Malabar, 
Ceylon, Jamaica, and almoft every where within the tro¬ 
pics, it has the leaves fmooth and green on both (ides, like 
Plumbago zeylanica ; broader than in the Sicilian plant, and 
A C I 75 
dotted underneath: but the appearance, fpike, ftature, 
flower, &c. being the fame in both, they are not diftindt 
fpecies. 
2. Achyranthes lappacea, or burry achyranthes: ftem 
flirubby, ditfufed, profirate; fpikes interrupted; lateral 
flowers having a bundle of hooked briftles on each fide. 
This is a native of Malabar and Ceylon. 
3. Achyranthes muricata, or prickly achyranthes: ftem 
flirubby, patulous; leaves alternate; flowers in remote 
ovate fpikes; calyxes fquarrofe. Leaves pctioled, ovate, 
entire, almoft naked. Spike alternate, peduncled, long, as 
in the firft fpecies, but the flowers more remote, more 
ovate, and not reflex, but three feales of the calyx ftiort- 
er. Native of India. 
4. Achyranthes patula, or fpreading achyranthes : ftem 
flirubby, patulous, pubefeent; flowers in orbicular fpikes, 
hedgehog-hooked. In a ftate of deep, the oppofite leaves 
of this fpecies are bent down under the branch, and ap¬ 
proximate to the under furface. It is a native of the Eaft 
Indies. 
5. Achyranthes alternifolia, or alternate-leaved achy¬ 
ranthes i fteni herbaceous, eredl; flowers in fubglobular 
burrs. This fpecies is alfo a native of the Eaft indies. 
6. Achyranthes corymbofa, or corymbed achyranthes: 
leaves four-fold, linear; panicle dichotomous corymbed. 
The flowers refentble thofe of cdofia, and it was put into 
that genus formerly by Linnaeus. It is found in Ceylon. 
7. Achyranthes dichotoma, or dichotomous achyran¬ 
thes: ftems fuffruticofe, leaves oppofite lifiear flat acute; 
cyme dichotomous. This very much refembles the fore¬ 
going : it grows in Virginia. 
8. Achyranthes proftrata, or profirate achyranthes : the 
ftems profirate flirubby; fpikes oblong; fiofcules in pairs, 
with a hooked fafcicle on each fide. • This is a native of 
India. 
9. Achyranthes nivCa, or white achyranthes: leaves 
veticilled ovate tomentofe, corymbs compact dichotomous, 
flowers corolled. It is a native of the Canary ifiands, 
v.'hence it was introduced here by Mr. Francis Maflbn, in 
1780. It flowers from May to July. 
10. Achyranthes altiflima, or tall achyranthes: ftem fitf- 
fruticofe fcandent, panicles terminating and axillary, 
branched. The ftalks of this fpecies climb up trees to th'e 
height of twenty feet. It is common among low bufhes 
about Spanifh Town and Kingfton, in Jamaica ; and in the ■ 
woods of St. Domingo. 
11. Achyranthes polygoncides: ftem decumbent four- 
cornered, leaves ovate-cordate, fpikes lax, fiiort. This 
fpecies was found in Arabia by Forlkahl, and in Malabar 
by Koenig. It refembles the polygonum orienta/e m leaves and 
fpikes, but the latter are lefs compaft. The Arabians 
call this plant didjar and buo'jer: from the firft of thefe the 
trivial name is formed. 
Propagation and Culture. The firft fort has been long 
known in England; but neither tiiis, nor any of the others, 
having much beauty to recommend them, they are only 
preserved in botanic gardens. The firft may be raifed on 
a hot-bed from the feeds, and when the plants have ac¬ 
quired ftrength, they may be removed into the full ground, 
where they will flower in July, and the feeds will ripen in. 
September. If they are kept in pots, and fet into a warm 
green-houfe in winter, they will live two or three years. 
—The other forts muft be placed in a ftove to preferve. 
them through the winter: except the ninth, which wdl 
live in a green-houfe. 
ACI A,/ [from the vernacular name aciova, in Guiana.) 
In botany, a genus of the monadelphia dodecandria clafs, 
of the natural order of pomaceae. 1 he generic charac¬ 
ters are—Calyx: perianthium one-leafed, turbinate, cur¬ 
ved; border five-parted; parts'roundifh, fpreading; the 
uppermoft and two loweft larger; the two middle ones 
fmaller. Corolla: petals five, oblong, rounded ; the three 
upper longer, afeending; the two lower (horter. Stami¬ 
na: filaments twelve, unequal, uniting at bottom in a li¬ 
near fleflvy membrane, infer ted into the calyx between the- 
/two- 
