EXP 
6 35 - 
EXP 
afterwards by th'e electric spark, be found 
that the force of the explosion was directed 
’more towards one part of the vessel than an- 
other; least on that part where the electrical 
discharge was made, and most upon that 
which was farthest from it. This inequality 
whs very considerable; insomuch that he 
could not repeat his experiments any number 
of times without injuring the vessel in that 
part which was farthest from the discharge. 
The reason he gives for this is, that the mix- 
ture was not tired at the same instant, but 
first at the place where the discharge was 
made. 'I’liis first explosion would have acted 
equally upon all parts of the vessel, had it 
not been for the intervention of the air. Bv 
the first momentary exj losion, however, the 
air in the farthest part of the vessel w as con- 
densed, so that the next explosion was made 
stronger, while the copper in the tore part ot 
the vessel had the whole of this strong explo- 
sion to resist, the hinder part being but little 
concerned, <js the sir in it w3.s condensed 3>nd 
reduced almost to u vncuum. # 
Though the phenomena of explosions are 
sometimes very destructive, they are likewise 
of considerable use in life, by removing ob- 
stacles which could scarcely be got the better 
of by any mechanical pow er whatever. 1 he 
principal of these are the blowing up ot rocks, 
the separating of stones in quarries, and other 
purposes of that kind. The destruction occa- 
sioned by them in times of war, and the ma- 
chines termed upon the principle of explo- 
sion for the destruction of the human race, 
are well known ; and if we cannot call these 
useful, some take them at least to be neces- 
sary evils. For the production of explosions, 
gunpowder is the only substance that has }et 
been found to answer; nevertheless, as its use 
is attended with considerable expence, 
several attempts have been made to find out 
a cheap substitute lor it. One of the most 
remarkable of these was by mixing small 
quantities of water inclosed in little bladders, 
or some easily destructible vehicles, along 
with a charge of powder. By this contriv- 
ance it was hoped that the water, being con- 
verted into vapour when the powder w as in- 
flamed, would augment the iorce ot the ex- 
plosion; but instead ot his, it was found 
greatly to diminish it. T1 e reason was evi- 
dent, viz. that the conversion ot the water 
into ^steam required so ngyeh of the latent 
heat of the inflamed gunpowder, that enough 
was not left to give the necessary expansion 
to the aerial fluid produced. 
The effects of explosions, when violent, 
are felt at a considerable distance, by reason 
of the concussions they give to the atmo- 
sphere ; for, as it has been already hinted, all 
of them act upon the atmospherical fluid 
with the very same force they exert upon 
-terrestrial substances subjected to their ac- 
tion. Sir William Hamilton relates, that at 
the explosions of Vesuvius in 1767, the doors 
and windows of the houses at Naples flew 
open it unbolted, and one door was burst 
open, though it bad been locked. A gieat 
quantity of gunpowder being put into the 
flitch of a fortified city, and set on fire, de- 
stroyed part of the wall, and broke down one 
of the gates. The blowing up of powder- 
magazines or powder-mills will destroy build- 
ings and kill people, though certainly with- 
out the reach ot the flame, and untouched 
by any part of the shattered magazine or 
EXP 
mill. But the most curious effect is, that 
they electrify the air, and even glass-win- 
dows, at a considerable distance. T his is al- 
ways observable in firing the guns of the 
Tower at London; and some years ago, after 
an explosion of some powder-mills in the 
neighbourhood of that city, a great number 
of people were alarmed by a rattling and 
breaking of their china-ware, which by the 
vulgar was taken for a supernatural pheno- 
menon, but undoubtedly was owing to some 
commotion in the electrical fluid, fiont the 
violent concussion of the atmosphere. _ In 
this respect, however, the effects of electrical 
explosions themselves are most remarkable, 
though not in the uncommon way just men- 
tioned ; but it is certain, that the influence of 
a flash of lightning is diffused for a great way 
round the place where the explosion happens, 
producing many very perceptible changes 
both on the animal and vegetable creation. 
EXPONENT, in algebra, is a number 
placed over any power or involved quantity, 
to shew to what height the root is raised : 
thus, 2 is the exponent of x 2 , and 4 the ex- 
ponent of x 4 , or xxxx. See Algebra. 
Exponent of (I ratio, is the quotient aris- 
ing from the division of the antecedent by 
the consequent: thus, in the ratio of 5 to 4, 
the exponent is 1 J; but the exponent ot 4 : 5, 
is 4-5ths. 
EXPONENTIAL Curve, is that the nature 
of which is expressed by an exponential equa- 
tion. The area of any exponential curve whose 
nature is expressed by this exponential equa- 
tion x y (making 1 -]— u w), will be 
1 „* 4 l — - „ 3 — ® 4 4 - 
0 . 1 . 2 ” ^ 0 . 1 . 2.3 0 . 1 . 2 . 3. 4 n 
? iP ^ if, See. 
0 . 1 . 2 . 3 . 4. 5 0 . 1 . 2 . 3 . 4 . 5 . 6 
Exponential equation is that wherein 
there is an exponential quantity. See the next 
article. 
Exponential quantity is a quantity whose 
power is a variable quantity, as w , a . Expo- 
nential quantities are of several degrees and or- 
ders, according as the exponents themselves are 
more or less involved. If the exponent be a sim- 
ple quantity, as z y , it is called an exponential 
of the first or lowest degree ; but when the ex- 
ponent itself is an exponential of the first de- 
X 
gree, as z y , it is called an exponential of the 
second degree. In like manner, if the exponent 
itself be an exponential of the second degree, as 
x° 
x y , it is called an exponential of the third de- 
gree, See. 
Total official value of the exports 
From London — 
Outports — 
England — 
Scotland — — 
EXPORTATION, the act of sending, 
goods out of one country into another. In 
modern times it has been the principal object 
of commercial policy, in almost every coun- 
try, to encourage exportation, except with 
respect to a few particular articles ; the ex- 
port of manufactured goods has been pro- 
moted with the view of encouraging the in- 
ternal industry of the country, and the export 
of foreign produce, as a means of drawing 
wealth from other countries by the profits of 
the carrying-trade. The excess of the va- 
lue of goods exported, beyond that of the 
imports, has usually been considered as a 
criterion of the profits which a country de- 
rives from foreign trade ; but this is a very 
fallacious mode of determining a point of 
great importance ; advantageous foreign trade 
might long exist, even if the imports con- 
stantly exceeded the value of the exports. 
See Political Arithmetic. 
The laws in force relating to exportation 
consist principally of prohibitory or restric- 
tive regulations respecting bullion, corn, 
wool, machinery, and tools used in various 
branches of manufactures, the exportation of 
which it is thought might diminish the neces- 
sary supply of provisions for the consump- 
tion of the country, or enable foreigners to 
rival valuable branches of its manufactures. 
The acts relative to the exportation of wool 
prohibit the exportation not only of the arti- 
cle itself* but also of live sheep, rams, or 
lambs, from Great Britain, Ireland, Jersey, 
Guernsey, Alderney, Sark, or Man, on pe- 
nalty of the forfeiture thereof, and of the 
ships conveying the same ; also 3i. tor every 
sheep, &c. and the offender to suffer three 
months solitary imprisonment ; for a second 
offence 5/. per sheep, &c. and six months 
imprisonment : except wether sheep for 
ships’ use only, put on board by licence of 
the port-officer of the customs. A limited 
quantity of wool is, however, permitted to be 
exported from the port of Southampton to 
Jersey, Guernsey, Alderney, and Sark. 
The duties on exportation, payable in 
Great Britain and Ireland, which were for- 
merly the principal branch of the revenue 
derived from foreign trade, are now of small 
amount in comparison with the duties pay- 
able on goods brought into the country. See 
Customs. 
For the extent of the several branches of 
the export trade of Great Britain, and the ar- 
ticles of which they consist, see Com* 
merce. 
of Great Britain in the year 1800. 
£. 
s. 
d. 
25,428,922 
16 
7 
15,377,027 
1 
3 
40,805,949 
17 
10 
2,346,069 
7 
8 
43,152,019 
5 
6 
