SHE 
also the Lituites, a fossil shell, bearing a 
very close resembance, in form, to the 
recent shells of this genus, but very far 
exceeding them in size. 
Belemnites, a many-chambered straight, 
long, conical pointed shell, full at its sum- 
mit, 'and possessing a lateral cleft. These 
are only known in a mineral state. 
StlKLl., in chemistry. Shells of marine 
animals, and of all eggs, consist chiefly of 
carbonate of lime, and yield a very pure 
lime, for which they are used on the sea- 
coast. They aflFord, likewise, a small por- 
tion of phosphate of lime. There are two 
great classes of marine shells, the testaceous 
and crustaceous. The former are by much 
the most numerous, and include all the ma- 
rine shell animals that have not legs, and 
the power of transporting themselves from 
place to place. The crustaceous shells are 
those of the lobster, crab, prawn, &c. who 
carry their shell as a protection from exter- 
nal injury, and not as a place of residence. 
Mr. Hatchet has made many experiments 
on shells, and he obseives, that marine 
shells for the most part are either of a por- 
cellaneous aspect, with an enamelled sur- 
face and fibrous texture, or they are com- 
posed of the substance called nacre, or mo- 
ther of pearl. The first kind dissolved in 
acids with strong effervescence, and their 
solutions afforded no trace of the pTTosphate 
of lime : tliey contained only carbonate of 
lime, and the animal matter, which acts as 
a cement to this, and which he supposes to 
be albumen in various states of induration : 
this is in small proportion ; hence shells ex- 
posed to heat exhale but little empyreuma- 
tic animal odour ; they emit no smoke, and 
when dissolved in acids no vestige of it can 
be discovered. In .shells of the other de- 
scription approaching to nacre, the earthy 
matter is carbonate of lime, but in a smaller 
proportion, while the animal matter is in 
considerable quantity. These give out 
smoke and an empyi eumatic odour when 
exposed to heat ; and when acted upon by 
acids, give out less car bonic acid gas, and 
leave a large quantity of a membranaceous 
or cartilaginous residuum. This substance 
often constitutes a large part of the shell, as 
in that of the oyster or muscle, and is so 
much indurated as to be no longer gelati- 
nous j and in all shells of this division it 
appears to be deposited in layers, each hav- 
ing a corresponding coat of carbonate of 
lime. 
Sheli.s, in grtimery, are hollow iron 
balls to throw' out of niortars or howitzers, 
SHE 
with a fuze-hole of about an inch diameter, 
to load them with powder, and to receive 
the fuze : the bottom, or part opposite the 
fuze, is made heavier ihaii the rest, that the 
fuze may fall uppermost; but in small ele- 
vations this is not always the case, nor is it 
necessary ; for let it fall as it will, the fuze 
sets fire to the powder within, which bursts 
the shell, and causes great devastation. 
The shells had much better be made of an 
equal thickness, for then they burst into 
more pieces. 
Shells, message, are nothing more than 
howitz shells, in the inside of which a letter, 
or other papers, are put. The fuze-hole is 
stopped up with wood or cork, and the shells 
are fired out of a royal or howitz, either in- 
to a garrison or camp. It is supposed that 
the person to whom the letter is sent knows 
the time, and accordingly appoints a guard 
to look out for its arrival. 
“ To find the weight of a Shell.” Rule. 
Double the difference of diameters of the 
shell and hollow sphere, and seven times 
the result gives the weight in pounds, cut- 
ting off the two right-hand figures of whole 
numbers. Ex. Let the diameter of the 
shell be l.S inches, and that of the hollow 
sphere 9.5. Then the cube of 13 is 2197, 
and that of 9.5 is 857.357 ; the difference is 
13;39.625, its Rouble is 2679.25, which mul- 
tiplied by 7, gives 18754.625 ; and cutting 
off two places in whole numbers, the result 
is 187 lb. or l cwt. 2 grs. 21 lb,, the weight 
of the shell. 
Shell, a particular part of a sword, 
which serves as a shield to the hand wben 
It grasps the hilt. The regulation sword, 
which is directed to be worn in a cross belt, 
has its shell so constructed that one .side can 
fall down, by wliicli means the hilt hangs 
more conveniently. 
Shell, a short jacket without arms, 
which was worn by light dragoon-s, and in 
some instances by the infantry, before the 
new regulations took place, respecting the 
clothing of tlie British army. At the com- 
mencement of the present war, some mi- 
litia colonels derived no inconsiderable 
emolument from this mode of dress. 
SHELVES, in naval affairs, a general 
name given to any dangerous shallows, 
sand-banks, or rocks, lying immediately 
under the surface of the water. 
SHERARDIA, in botany, so named in 
honour of William Sherard, LL.D. consul 
at Smyrna, a genus of the Tetrandria Mo- 
nogynia class and order. Natural order of 
Stellatm. Rubiaceaj, Jussieu. Essential cha- 
H 2 
