.1 RTS. 
37S 
mon bow; that there are fcarcely above two colours’dif- 
tinguifhable, a dark yellow on the fide next the fun, and 
a pale green on the oppofite fide. But they are more nu¬ 
merous, there being fometimes twenty or thirty feen 
together. 
To this clafs of bows may be referred a kind of white 
or colourlefs rainbows, which Mentzelius and others affirm 
to have feen at noon-day. M. Marlotte, in his fourth 
Eflai de Phyfique, fays, thefe bows are formed in mills, as 
the others are in (bowers; and adds, that he has feen fe- 
veral both after fun-riling and in the night. The want 
of colours he attributes to the fmallnefs of the vapours 
which compofe the mill; but perhaps it is rather from 
the exceeding tenuity of the little veficulse of the vapour, 
which being only little watery pellicles bloated with air, 
the rays of light undergo but little refraflion in palling 
out of air into them ; too little to feparate the differently- 
coloured rays, See. Hence the rays are reflected from 
them, compounded as they came, that is, white. Rohault 
mentions coloured rainbows on the grafs, formed by the 
refractions of the fun’s rays in the morning dew. Rain¬ 
bows have been alfo produced by the reflection of the 
fun from a river; and in the Philofophical Tranfailions, 
vol. i. p. 294, we have an account of a rainbow, which 
mull havebeen formed by the exhalations from the city 
of London, when the fun had been fet twenty minutes, 
and confequently the centre of the bow was above the 
horizon. The colours were the fame as in the common 
rainbow, but fainter. See the article Optics. 
It has often been made a fubjeCl of inquiry among the 
curious how there came to be no rainbow before the flood, 
which is thought by fome to have been the cafe from its 
being made a lign of the covenant which the Deity was 
pleafed to make with man after that event- Mr. White- 
hurll, in his Inquiry into the Original State and Forma¬ 
tion of the Earth, p. 173, &c. endeavours to ellablilh it 
as a matter of great probability at lead, that the ante¬ 
diluvian atmofphere was fo uniformly temperate as never 
to be fubjeCl to dorms, tempeds, or rain, and of courfe it 
could never exhibit a rainbow. For our own part, we 
cannot fee how the earth at that period could do without 
rain any more than at prefent; and it appears to us from 
Scripture equally probable that the rainbow was feen be¬ 
fore the flood as after it. It was then, however, made a 
token of a certain covenant; and it would unquedionably 
do equally well for that purpofe if it had exided before 
as if it had not. 
I'RIS, f. (fo named from the variety of colours in the 
flowers.] In botany, a genus of the clafs triandria, order 
monogynia, in the natural order of enfatas, (irides, JuJf.) 
The generic characters are—Calyx: fpathes bivalve, fepa- 
rating the flowers, permanent. Corolla: fix-parted; petals 
oblong, obtufe; the three exterior ones reflex; the three 
interior upright and lharper; all connefted at the claws 
into a tube of different lengths in the different fpecies. 
Stamina: filaments three, awl-lhaped, incumbent on the 
reflex petals; antherae oblong, flraight, depreffed. Piflil- 
lum : germ inferior, oblong; flyle Ample, very fhort; dig- 
mas three, petal-form, oblong, carinated within, furrowed 
without, incumbent on the flamens, two-lipped. Outer 
lip finaller, emarginate; inner larger, bifid, fubinflefted. 
Perlcarpium: capfule oblong,cornered, three-celled, three- 
valved. Seeds: feveral, large. The neftary in fome (1-9) 
is a longitudinal villofe line, engraven on the bafe of the 
reflex petals; but in others it confids of three melliferous 
pores at the bafe of the flower. The capfule in fome is 
trigonal, in others hexagonal. —EJfential Chara&cr. Co¬ 
rolla fix-petalled, unequal; petals alternate, jointed and 
fpreading; digmas petal-form, cowled-two-lipped. 
Species. I. Bearded. 1. Iris ciliata, or ciiiate-leaved 
iris: bearded; leaves enfiform, ciliate. Bulb ovate, 
fibrous, netted, the fize of a ljazel-nut. Scapes feveral, 
mod el them concealed by the (heaths of the leaves, and 
a single one only flowering; this is wholly fheathed by 
leaves, Ample, compreffed, weak, white, fmooth, upright, 
Vol. XI. No. 760. 
one-flowered, a palm in height. Leaves radical, about 
fix, convoluted at the bafe, alternately fheathing the fcape 
to the very top, acuminate, front upright fpreading or 
curved back, nerved, fmooth, entire, nearly equal to the 
fcape, the inner ones gradually fhorter, and more convo¬ 
luted. Corolla yellow; the, fmaller petals obovate; the 
inner lip of the lligma bifid, the fegments brifcle-fliaped, 
the length of the ltigma. Capfule tlnr.e-cornered, three- 
grooved. Native of the Cape of Good Hope, on the hills 
near Cape Town. 
2. Iris minuta, or minute iris: bearded; leaves enfi¬ 
form, fmooth; fcape one-flowered; petals oblong, acute 
Bulb ovate, netted, the fize of a large pea. Scape Ample, 
fheathed with leaves, upright, a palm in height. Leaves 
about four, alternately iheathing, fubfalcate-reflex, entire; 
fmooth, equalling the fcape, the upper ones gradually 
fhorter. Corolla yellow, the fmaller petals lanceolate. 
Native alfo of the Cape, on Leuweltart mountain near Cape 
Town. Thefe were both firll obferved by Thunberg. 
3. Iris pumila, or dwarf iris: bearded; leaves enfiform,, 
fmooth; fcape one-flowered ; petals oblong, blunt. Root 
brownilh on the outfide, white within, knobbed, with pale 
fibrils. Leaves acute, fometimes ihorter,fometimes longer,, 
than the flower. Stem Or fcape very lhort, often fcarcely 
an inch in length. Germ oblong, bluntly and obfcurely 
three-cornered, an inch long, inclofed within two fpathes, 
ending in the tube of the corolla, which is (lender, and 
from two to three inches in length. All the petals are. 
almolt entire, blue or purple, varying much in colour, in- 
fomuch that the fame flower changes, and from blue be¬ 
comes more and more red ; outer beards blue, inner white, 
with yellow tips; antherae blue ; lligmas deeply bifid and 
acuminate, ufually of the fame colour with the corolla. 
The fruit is feldom obferved in this fpecies -. it is ovate, 
bluntly three-cornered, an inch long; feeds wrinkled, an¬ 
gular, yellow-rufl-coloured. Native of Aultria and Hun¬ 
gary on open hills, flowering in April. It was cultivated 
in 1596 by Gerarde. There are many varieties of this 
Fort, with white, flraw-coloured, pale blue, blufh-coloured, 
yellow-variable, blue-variable, and other colours in the 
flowers, which are now in great meafure neglected. 
4. Iris Sufiana, or Chalcedonian iris: bearded; leaves 
enfiform, fmooth; fcape one-flowered; petals rounded. 
Scape Ample, round, grooved, a fpan high. Leaves alter¬ 
nate, fheathing, upright, very finely flriated, obfcurely 
waved. Mr. Miller obferves, that the leaves are of a grey - 
ifh colour; that the flalks are two feet and a half high ; 
that the three upright petals of the flower are almolt as 
broad as a hand, but very thin, flriped with black and 
white; the three bending petals, or falls, of a darker co¬ 
lour; whence fome gardeners call it the mourning iris. It 
flowers at the end of May or beginning of June, but ne¬ 
ver bears any feeds in England. Native of the Levant. 
It takes the name from Sufa in Perfia. Clufius informs 
us that this magnificent iris was brought from Conllanti- 
nopie to Vienna and Holland in 1573; in 15.96 it wa* 
cultivated by our Gerarde. 
5. Iris Florentina, or Florentine iris: bearded; leaves 
enfiform, fmooth ; fhorter than the fub-biflorous fcape. 
Scape round, ftriated, Ample, upright, a foot high and 
more, bearing two or three flowers. It refembles I. Ger-- 
manica, No. 9, very much, but differs in having the pe¬ 
tals white and entire, the edges of the fmaller petals re¬ 
flex at the bafe, the larger ones more upright, and the lip 
of the fligma crenated and more upright. Native of the 
South of Europe. Cultivated in 1596 by Gerarde. It- 
fiowers in May and June. This is named by our old 
writers white flower-de-luce, or Jlower-de-luce of Florence. 
The root is extremely acrid, and when chewed excites a 
pungent heat in the mouth, which continues fome hours; 
on being dried, this acrimony is almofl Wholly diffipated, 
the talte being (lightly bitter, and the fniell agreeable, 
and approaching to that of violets. No effential oil has 
hitherto been obtained from this root, but fpirituous tinc¬ 
tures of it contain more of its virtues than watery infufion*. 
