LIG 
occupy its place in the centre of the flame ; 
neither does it, when there, enlarge the di- 
ameter of the flame, so as to prevent the ac- 
cess of air to its internal part. When its 
length is too great for the vertical position, 
it bends on one side ; and its extremity, com- 
ing into contact with the air, is burned to 
ashes, excepting such a portion as is defend- 
ed by tlie continual afflux of melted wax, 
which is volatilized and completely burned 
by the surrounding flame. We see, there- 
fore, that the difficult fusibility of wax ren- 
ders it practicable to burn a large quantity 
of fluid by means of a small wick ; and that 
this small w'ick, by turning on one side in 
consequence of its flexibility, performs the 
operation of snuffing upon itself, in a much 
more accurate manner than it can ever be 
performed mechanically. 
Miv Henry made some experiments on 
the light afforded by the combustion of dif- 
ferent gases, and found, that it was appa- 
rently in the ratio of the oxygen that enter- 
ed into combination with the hydrogen they 
contained. Thus, 100 parts of pure hydro- 
gen gas required from bO to 64 of oxygen ; 
100 of gas from oak, 42 ; from moist char- 
coal and from dried peat, each 50 ; from 
lamp oil 136 ; from coal 140 ; from wax 
166 ; pure olifiant gas 210. Tallow is 
nearly on a par with oil. The production 
of light from the first four was so triflings 
that they did not seem applicable to (Eco- 
nomical purposes. 
hiGHT from plants. In Sweden a very 
curious phenomena has been observed on 
certain flow'ers by M. Haggern, lecturer in 
natural history. One evening he perceived 
a faint flash of light repeatedly dart from a 
marigold. Surprised at such an uncommon 
appearance, he resolved to examine it with 
attention; and, to be assured it was no de- 
ception of the eye, he placed a man near 
him, with orders to make a signal at the 
moment when he observed the light. They 
both saw it constantly at the same moment. 
Tljp light was most brilliant on marigolds of 
an orange or flame colour ; but scarcely visi- 
ble on pale ones. The flash was frequently 
seen on the same flower two or three times 
in quick succession, but more commonly at 
intervals of several minutes: and when seve- 
ral flowers in the same ^lace emitted their 
light together, it could be observed at a 
considerable distance. This phenomenon 
was remarked in the months of July and 
August at sunset, and for half an hour when 
the atmosphere was clear; but after a rainy 
day, or when the air was loaded with va- 
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pours, nothing of it was seen. The follow- 
ing flowers emitted flashes, more or less 
vivid, in this order : 1. The marigold, ca- 
lendula officinalis. , 2 . Monk’s-hood, tropa:- 
olum majus. 3. The orange lily, liliura bul- 
biferum. 4. The Indian pink, tagetes pa- 
tula et erecta. 
To discover whether some little insects 
or phosphoric w'orms might not be the cause 
of it, the flowers were carefully examined, 
even with a microscope, without any such 
thing being found. From the rapidity of 
the flash, and other circumstances, it may 
be conjectured that there is something of 
electricity in this phenomenon. It is well 
knoM'n, that when the pistil of a flower is 
impregnated, the pollen bursts away by its 
elasticity, with which electricity may be 
combined. But BI. Haggern, after having 
observed the flash from the orange lily, the 
antherae of which are a considerable space 
distant from the petals, found that the light 
proceeded from the petals only ; whence he 
concludes, that this electric light is caused 
by the pollen, which, in flying oflrj is scat- 
tered on the petals. Whatever be the 
cause, the eftect is singular and highly cu- 
rious. 
Light house, a building erected upon a 
cape or promontory on the sea coast, or 
upon some rock in the sea, and having on its 
top in the night time a great fire, or light 
formed by candles, which is constantly at- 
tended by some careful person, so as to be 
seen at a great distance from the land. It 
is used to direct the shipping on the coast, 
that might otherwise run a-shore, or steer 
an improper course, when the darkness of 
the night and the uncertainty of currents, 
&c. might render their situation with regard 
to the shore extremely doubtful. Lamp- 
lights are, on many accounts, preferable to 
coal fires or candles; an^ the effect of 
these may be increased by placing them 
either behind glass hemispheres, or before 
properly disposed glass or metal reflectors, 
which last method is now very generally 
adopted. See Beacons. 
LIGHTFOOTIA, in botany, so named 
iji honour of John Lightfoot, a genus of the 
Polygamia Dioecia class anti order. Essen- 
tial character : calyx four-leaved ; corolla 
none : female and hermaphrodite, stigma 
sessile ; berry umbilicated, on'e-celled, with 
from three to six seeds. There are three 
species, all shrubs. 
LIGHTNING. It is now universally 
allowed, that lightning is really an electri- 
cal explosion or phenomenon. Philoso- 
