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and then, in Oh i' 0 " 38"' 57"' the star 
will have just completed its 366th revolu- 
tion to the meridian. 
SIDERITE, a name given by Bergman 
to a supposed peculiar metallic substance, 
which is the principal cause of the brittleness 
of some kinds of bar iron. This has long 
since been discovered as the phosphate of 
iron. • 
SIDERITIS, in botany, iron-wort, a ge- 
nus of the Didynamia Gymnospermia class 
and order. Natural order of Verticillatae. La- 
biatae, Jussieu. Essential character : calyx 
five-cleft; corolla ringent ; upper lip bifid, 
lower three-parted ; stamina within the tube 
of the corolla ; stigma, the shorter involving 
the other. There are twenty species. 
SIDEROXYLON, in botany, iron-wood, a 
genus of the Pentandria Monogynia class and 
order, Natural order of Duinosae. Sapotre, 
Jussieu. Essential character : corolla five- 
cleft ; nectary five-leaved ; stigma simple; 
berry five-seeded. There are nine spe- 
cies, chiefly natives of the Cape of Good 
Hope. 
SIEGE, in the art of war, the encamp- 
ment of an army before a fortified place, 
with a design to take it. Thejnethod of 
encamping is very diflferent in a siege, from 
that observed on a march ; as in the former 
the army environs the place, without cannon 
shot, that nothing may enter. If the place 
be situated on a river, a detachment is sent 
to the other side, and bridges of communi- 
cation made, both above and below the 
town. The army also encamp with their 
backs to the town, with the battalions and 
squadrons interlined ; and , having taken 
possession of all the heights, whence the 
enemy may be annoyed, the engineers trace 
the lines ofcircumvallation and contravalla- 
tion ; every regiment working at the place 
appointed them. .See Fortification. 
Captain James, in his Military Dictionai-y, 
has given the following rules, which ought to 
be adopted in sieges. The approaches 
should be made without being seen from the 
town, either directly, obliquely, or in the 
flank. No more works should be made 
than are necessary for approaching the 
place without being seen ; i. e. the be- 
siegers should carry on their approaches 
the shortest way possible, consistent with 
being covered against the enemy’s fire. All 
the parts of the trenches should mutually 
support each other ; and those which are 
furthest advanced, should be distant from 
those that defend them above 120 or 130 
toises, that is, within musket-shot. The pa- 
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rallels, or places of arms the most distant 
from the town, should have a greater ex- 
tent than those which are the nearest, that 
the besiegers may be able to take the 
enemy in flank, should he resolve to attack 
the nearest parallels. The trench should be 
opened or begun as near as possible to the 
place, without exposing the troops too 
much, in order to accelerate and diminish 
the operations of the siege. Care should 
be taken to Join the attacks ; that is, they 
should have communications, to the end 
that they may be able to support each 
other. Never to advance a work, unless 
it be well supported ; and for this reason, 
in the interval between, the second and 
third place of arms, the besiegers should 
make, on both sides of the trenfches, smaller 
places of arms, extending 40 or 50 toises 
in length, parallel to the others, and con- 
structed in the same manner, which will 
serve to lodge the soldiers in, who are to 
protect the works designed to reach the 
, third place of arms. Tak.e care to place 
the batteries of cannon in the continuation 
of the faces of the parts attacked, in order 
to silence their fire ; and to the end that the 
approaches, being protected, may advance 
with great safety and expedition. For this 
reason the besiegers shall always embrace 
the whole front attacked, in order to have 
as much space as is requisite to place the 
batteries on the produced faces of the works 
attacked. Do not begin the attack with 
works that lie close to one another, or with 
rentrant angles, which would expose the at- 
tack to the cross fire of the enemy. 
“ Stores required for a month’s siege are 
as follow powder, as the garrison is more 
or less strong, 8 or 900,0001ft. ; shot for 
battering pieces, 6,000 ; shot of a lesser 
sort, 20,000 ; battering cannon, 80 ; cannons 
of a lesser sort, 40 ; small field-pieces for 
defending the lines, 20 ; mortars for throw- 
ing shells, 24 ; mortars for throwing stones 
12 ; shells for mortars, 15 or 16,000 ; hand- 
grenades, 40,000 ; leaden bullets, 180,000 ; 
matchesin braces, 10 , 000 ; flints for muskets’ 
best sort, 100,000 ; platforms complete for 
guns, 100 ; platforms for mortars, 60 ; spare 
carriages for guns, 60 ; spare mortar-beds, 
60 ; spare spunges, rammers, and ladles, in 
sets, 20 ; tools to work in trenches, 40,000. 
Several hand-jacks, gins, sling-carts, tra- ' 
veiling forges, and other engines proper to % 
raise and carry heavy burdens ; spare 
timber, and all sorts of miner’s tools, mant- 
lets, stuffed gabions, fascines, pickets, and 
gabions. 
