663 SID 
in strata, of which there are sometimes six ; 
they are not quite straight, but preserve an 
undulating direction, so as to lornr a net- 
work in their natural positions. Their smell 
resembles that of hemp ; the fibres are whiter, 
but more dry and harsh, than those of hemp. 
The harshness is owing to a greenish 
gluten which connects the libres ; and the 
white colour must always be obtained at the 
expence of having this kind of thread less 
pupple ; when of its natural hue, it is Very 
soft and flexible. 
S1DERIA, in natural history, the name of 
a genus of crystals, used to express those al- 
tered in their figure by particles of iron. 
These are of a rhomboidal figure, and com- 
posed only of six planes. Of this genus there 
are four known species: 1. A colourless, 
pellucid, and thin one; found in considerable 
quantities among the iron ores of the forest 
of Dean in Gloucestershire, and in several 
other places. 2. A dull, thick, and brown 
one, not uncommon in the same places with 
the former. And, 3. A black a;id very 
glossy kind, a fossil of great beauty ; found 
m the same place with the others, as also in 
Leicestershire and Sussex. 
SI DERI FE, a substance discovered by 
Mr. Meyer, and by him supposed to be a 
new metal ; but Messrs. Bergman and Kir- 
wan discovered that it is nothing else than a 
natural combination of the phosphoric acid 
with iron. Mr. Klaproth of Berlin also 
came to the same conclusion, without any 
communication with Mr. Meyer. It is ex- 
tremely difficult to separate this acid from 
the metal ; however, he found the artificial 
compound of phosphoric acid and iron to 
agree in its properties with the calx sideri 
alba, obtained by Bergman and Meyer from 
the cold short iron extracted from the swampy 
or marshy ores. 
SRDERITIS, Ironwort ; a genus of 
plants belonging to the class ot didynamia, 
and to the order ot gymnospermia ; and m 
the natural system ranging under the 42d 
order, verticillaUe. The stamina are within 
the tube of the corolla. There are two stig- 
mas, one of whit h is cylindrical and concave ; 
the other, which is lower, is membranous, 
shorter, and sheathing the other. The spe- 
cies are 19- 
SIDEROKYLUM, Iron-wood : agfcmis 
of plants belonging to the class of pi itandria, 
and to the order of monogynia ; and in the 
natural system ranging under the 43ci order, 
dumosa?. The corolla is cut into five parts, 
the laciilia? or segments being mcurvated al- 
ternately ; the stigma is simple; the berry 
contains five seeds, t here are nine species ; 
1. Mite; 2. inenne, smooth iron-wood ; 3. 
melanophleum, laurel-leaved iron-wood ; 
4. cymosum ; 5. sericeum, silky iron-wood, 
native of New South Wales; 6. tomen- 
tosum ; 7. tenax, silvery-leaved iron-wood, 
a native of Carolina ; 8. lyoioid.-s, willow- 
leaved iron-wood, a native of North Ame- 
rica ; 9. decandrum. The wood of these 
trees being very close and solid, has given 
occasion for this name to be applied to them, 
it being so heavy as to sink m water. As 
they are natives ot warm countries, they can- 
not be preserved in this country unless they 
are placed, the two former in a warm stove, 
the others in a green-house. They are pro- 
pagated by seeds, when these can be procur- 
ed from abroad. 
* I G 
SIEGE, in the art of war, the encamp- 
ment of an army before, a fortified place, with 
a design to take it. 
S1ENI1 E. See Rocks, primitive. 
SIGESBECKIA, a genus of plants belong- 
ing to the class syngenesia. and to the order 
of polvgamia superflua, and in the natural 
system ranging under the 49th order, com- 
po^itae. The receptacle is paleaceous ; the 
pappus wanting ; the exterior calyx is pen- 
taphyllous, proper, and spreading ; the radius 
is halved. There are three species : 1. The 
orientals, which is a native of India and 
China. 2. The occidentalis, which is a na- 
tive of Virginia. 3. The flosculosa, a native 
of Peru. 
SIGHTS of a quadrant, &c. thin pieces 
of brass, raised perpendicularly on its side, or 
on the index of a theodolite, circumferentor, 
&c. They have each an aperture, or slit, 
up the middle, through which the visual rays 
pass to the eye, and distant objects are seen. 
Sights of a gun. See Rifle. 
SIGN, in astronomy, a constellation con- 
taining a twelfth part of the zodiac, or 30°. 
See Zodiac. 
The names of the signs, in the order where- 
in they follow each other, are aries, taurus, 
gemini, cancer, !eo, virgo, libra, Scorpio, 
Sagittarius, capricornus, aquarius, pisces. 
The three first of these signs are called the 
vernal, or spring-signs ; the next three, 
cancer, leo, virgo, the sestival, or summer- 
signs ; libra, scorpio, and Sagittarius, the au- 
tumnal signs; and capricornus, aquarius, pis- 
ces, the brumal, or winter-signs. The vernal 
and aestival signs are also called the northern, 
and the autumnal and brumal the southern 
signs. 
Sign-manual, in law, is used to signify a 
bill, or writing, signed .by the king’s own 
hand- writing. 
SIGNALS, certain alarms or notices used 
to communicate intellig nee to a distant ob- 
server. Signals are made by firing artillery, 
and displaying colours, lanterns, or fire- 
works ; and these are combined by multipli- 
cation and repetition. Thus, like the words of 
a language, they become arbitrary expres- 
sions, to which we have previously annexed 
particular ideas ; and hence they are the ge- 
neral sources of intelligence throughout a 
naval armament, &c. 
Signals ought to be distinct, with simplicity'. 
They are simple when every instruction i$ 
expressed by a particular token, in order to 
avoid any mistakes arising from the double 
purport of one signal. They are distinct 
when issued without precipitation, when suf- 
ficient time is allowed to observe and obey 
them, and when they are exposed in a con- 
spicuous place, so as to be readily perceived 
at a distance. 
All signals may be reduced into three dif- 
ferent kinds, viz. those which are made by 
the sound of particular instruments, as the 
trumpet, horn, or fife ; to which may be 
added, striking the bell, or beating the drum. 
Those which are made by displaying pen- 
dants, ensigns, and flags of different colours ; 
or by lowering or altering tire position ol the 
sa ls . and, finally, those which are executed 
by rockets ot different kin :!s ; by firing can- 
non or small arms; by artificial fire-woiks; 
and by lanterns. 
i Fu ng of great guns will serve equally in 
| the day or night, or in a fog, to make -or con- 
15 I G 
| firm signals, or to raise the attention of the* 
hearers to a future order. This method, 
however, is attended with some inconveni- 
ences, and should not be used indiscrimi- 
nately. Too great a report of the cannon is 
apt to introduce mistakes and confusion, as 
w ell as to discover the track of the squadron. 
The report and flight of rockets is liable 
to the same # objection, when at h short dis- 
tance from the enemy. 
it is tiien by the combination of signals, 
previously known, that the admiral conveys 
orders to his fleet; every squadron, every 
division, and every ship of which, has its par- 
ticular signal. The instruction may there- 
fore occasionally be given to the whole fleet,, 
or to any of its squadrons ; to any division 
of those squadrons, or to any ship of those 
divisions. 
Hence the signal of command may at the 
same time be displayed for three divisions, 
and for three ships of each division ; or for 
three ships in each squadron, and for only 
nine ships in the whole fleet. For, the ge- 
neral signal of the fleet being shown, if a par- 
ticular pendant is also thrown out from some 
particular place on the same mast with thal 
general signal, it will communicate intelli- 
gence to nine ships that wear the same pen- 
dant. 
The preparatory signal given by the ad-' 
miral to the whole or any part ot his fleet, 
is immediately answered by those to whom 
it is directed ; by showing the same signal, 
to testify that they are ready to put his order* 
in execution. Having observed their answer, 
he will show the signal which is to direct their 
operations : as, to chase, to form the line, 
I to begin the engagement, to board, to double 
I upon the enemy, to rally or return to action, 
to discontinue the fight, to retreat and save 
. themselves. The dexterity of working the 
ships in a fleet depends on the precise mo- 
ment of executing these orders, and on the 
general harmony of .their movements ; a cir- 
cumstance which evinces the utility of a sjg- 
: nal of preparation. 
1 As the extent of the line of battle, and the 
fire and smoke of the action, or other circum- 
stances in navigation, will frequently prevent 
the admiral’s signals from being seen through- 
out tlie fleet, they are always repeated by 
the officers next in command, by ships ap- 
pointed to repeat signals; and, ‘finally, by. 
the ship or ships for which they are Intended. 
The ships that repeat the signals, besides 
the chiefs of squadrons or divisions, are usu- 
ally frigates lying to windward or to leeward 
of the line. They should be extremely vigi- 
lant to observe and repeat the signals, whether 
they are to transmit the orders of the com-] 
mander in chief, or his seconds, to any part 
of the fleet ; or to report the fortunate or dis- 
tressful situation of any part thereof. By this 
means all the ships from the van to the rear 
will, unless disabled, be ready at a moment’s 
warning to put the admiraPs. designs in exe- 
cution. 
To preserve order in the repetition of sig- 
nals, and to favour their communication, 
without embarrassment, from tire commander 
in chief to the ship for which they are calcu- 
lated, the commanders of the squadrons repeat 
after the admiral ; the chiefs of the divisions, 
accord ng to their order of the line, after the 
commanders of the squadrons ; and the par- 
ticular ships, after the chiefs of the. divisions 
