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EXP 
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•r bringing up phlegm, or other matters, out 
6f the trachea and lungs, bv coughing, &c. 
EXPEND1 POES, the persons who dis- 
burse or expend the money collected by the 
tax for repairs of sewers, after the same is 
paid into their hands by the collectors, as or- 
dered by the commissioners, and for which 
they are to render accounts when required. 
EXPENSIS MILITUM levandis, a writ 
antiently directed to the sheriff for levying 
the allowance for knights of the shire ; and 
cxpensis militum non levandis, was a writ to 
hinder the sheriff from levying such' allow- 
ance upon lands that held in antieut de- 
mesne, 
EXPERIMENTAL philosophy, that 
philosophy which proceeds on experiments ; 
which deduces the laws of nature, and the 
properties and powers of bodies, and their 
actions upon each other, from sensible expe- 
riments and observations. The business of 
experimental philosophy is to enquire into 
and to investigate the reasons and causes of 
the various appearances or phenomena of 
nature ; and to make the truth or probability 
wf them obvious and evident to the senses, by 
plain, undeniable, and adequate experiments, 
representing the several parts of the grand 
machinery and agency of nature. 
In our enquiries into nature, we are to be 
conducted by those rules and maxims which 
are found to be genuine, and consonant to a 
just method of physical reasoning; and these 
rules of philosophizing are by the greatest 
master in science, sir Isaac Newton, reckon- 
ed four, which are as follows: 
1. More causes of natural things arc not 
to be admitted, than are both true, and suffi- 
cient to explain the phenomena ; for nature 
does nothing in vain, but is simple, aiul de- 
lights not in superfluous causes of things. 
2. And, therefore, of natural effects of the 
flteame kind, the same causes are to be assign- 
ed, as far as it can be done; as of respiration 
in man and beasts, of the descent of stones in 
Europe and America, of light in a culinary 
lire and in the sun, and of the reflection of 
flight in the earth and in the planets. 
3. The qualities of natural bodies which 
cannot be increased or diminished, and agree 
to all bodies on which experiments can be 
made, are to be reckoned as the qualities of 
all bodies whatever; thus, because exten- 
sion, divisibility, hardness, impenetrability, 
mobility, the vis inertias, and gravity, are 
found in all bodies which fall under our cog- 
nizance or inspection, we may justly con- 
clude they belong to all bodies whatever, and 
are therefore to be esteemed the original and 
universalproperties of all natural bodies. 
4. In experimental philosophy, proposi- 
tion's collected from the phenomena by in- 
duction, are to be deemed (notwithstanding 
contrary hypotheses) either exactly or very 
nearly true, till other phenomena occur, by 
which they may be rendered either more ac- 
curate, or liable to exception. This ought to 
be done, lest arguments of induction should 
be destroyed bv hypotheses. 
These four rules of philosophizing are pre- 
mised by sir Isaac Newton to his third book 
of the iVmcipia ; and more particularly ex- 
plained by him in his Optics, where he ex- 
hibits the method of proceeding in philoso- 
phy, the lirst part of which is as follows : 
As in mathematics, so in natural history, 
the investigation of difficult, things, by way of 
analysis, ought always to precede the method 
of composition. This analysis consists in 
making experiments and observations, and in 
drawing general conclusions from them by 
induction (z. c. reasoning from ’the analogy of 
things by natural consequence); and admitting 
no objections against the conclusions, but 
what are taken from experiments or certain 
truths. And although the reasoning from 
experiments and observation, by induction, 
is no demonstration of general conclusions, 
yet it is the best mode of reasoning which the 
nature of t hings admits of, and may be looked 
on as so much the stronger, by 'how much 
the induction is more general ; and if no ex- 
ception occurs from phenomena, the con- 
clusion may be pronounced generally ; but if 
at any time afterwards, any exception shall 
occur from experiments, it may then be pro- 
nounced with such exceptions; by this way 
of analysis we may proceed from compounds 
to ingredients, and from motions to the causes 
producing them ; and in general from effects 
to their causes, and from particular causes 
to more general ones, till the argument ends 
in the most general; this is the method of 
analysis. And that of synthesis, or compo- 
sition, consists in assuming causes, discovered 
and established as principles, and by them 
explaining the phenomena proceeding from 
them, and proving the explanations. Though 
the whole history of nature is open to the re- 
searches of experimental philosophy, yet its 
principal branches may be accounted, attrac- 
tion, gravitation, the laws of matter and mo- 
tion, magnetism, optics, electricity, pneuma- 
tics, hydrostatics, hydraulics, and mechanics. 
EX PERIM ENTUM crucis, a leading, 
or decisive experiment ; thus termed, either 
on account of its being like a cross, or direc- 
tion post, placed in the meeting of several 
roads, guiding men to the true knowledge of 
the nature of that thing they are enquiring 
after; or, on account of its being a kind of 
torture, whereby the nature of the thing is in 
a manner extorted by force. 
EXPIATION, great day of, an annual so- 
lemnity of the Jews, upon the tenth day of 
the month Tisri, which answers to our Sep- 
tember. On this occasion the high priest 
laid aside his breastplate and embroidered 
ephod, as being a day of humiliation. He 
first offered a bullock and a ram for his own 
sins, and those of the priests; then he re- 
ceived from the heads of the people two 
goats for a sin-offering, and a ram for a burnt- 
offering, to be offered in the name of the 
whole multitude. It was determined by lot 
which of the goats should be sacrificed, and 
which set at liberty. After this lie perfumed 
the sanctuary with incense, and sprinkled it 
with blood ; then, coming out, he sacrificed 
the goat upon which the lot had fallen. This 
done, the goat which was to be set at liberty, 
being brought to him, lie laid his hands upon 
its head, confessed his sins and the sins of the 
people, and then sent him away into some 
desert place: it was called azazel, or the 
scape goat. 
EX PI I. AT I ON, among civilians, the car- 
rying off or sequestering something belong- 
ing to an inheritance, before the heir had in- 
termeddled with it. 
Expiration also denoted a robbery com- 
mitted by night, and was so called from the 
robbers stripping people of their clothes. 
4 II 2 1 
EXPLOSION, in natural philosophy, a 
sudden and violent expansion of an aerial or 
other elastic fluid, by which it instantly 
throws off any obstacle that happens to be 
in tire way, sometimes with incredible force, 
and in such a manner as to produce the most 
astonishing effects upon the neighbouring ob- 
jects. Explosion differs from expansion, in 
this : that the latter is a gradual and continued 
power, acting uniformly for some time; 
whereas the former is always sudden, and 
only of momentary duration. The expan- 
sions of solid substances do not terminate in 
violent explosions, on account of their slow- 
ness, and the small space through which the 
metal, or other expanding substance, move's, 
though their strength may be equally great 
with that of the most active aerial fluids. 
Thus we find, that though wedges of wood, 
when wetted, will cleave solid blocks of 
stone, they never throw them to any dis- 
tance, as is tire case with gunpowder. On 
the other hand, it is seldom that the expan- 
sion of any elastic fluid bursts a solid sub- 
stance, without throwing the fragments of it 
to a considerable distance, the effects ot which 
are often very terrible. The reasons of this 
may be comprised in the two following parti- 
culars. 1. The immense velocity with which 
the aerial fluids expand, when affected by a 
considerable degree of heat. 2. r l heir cele- 
rity in acquiring heat, and being affected by 
it, which is much superior to that of solid 
substances. Thus air, heated as much as 
iron when brought to a white heat, is expand- 
ed to four times its bulk ; but the metal itself 
will not be expanded the 500th part of that 
space. In the case of gunpowder, which is 
a violent and well-known explosive substance, 
the velocity with which the flame moves is 
calculated by Mr. Robins, in his treatise 
upon Gunnery, to be no less than 7000 feet 
in a second, or little less than 79 miles per 
minute. Hence the impulse of the fluid is 
inconceivably great, and the obstacles on 
which it strikes are hurried off with vast ve- 
locity, though much less than that just men- 
tioned; for a cannon-ball, with the greatest 
charge of powder that can be conveniently 
given, does not move at a greater rate than 
2400 feet per second, or little more than 27 
miles per minute. The velocity of the ball 
again is promoted by the sudden propagation 
of the heat through the whole body of the 
air, as scon as it is extricated from the mate- 
rials" of which the gunpowder is made, sd 
that it is enabled to strike all at once, and 
thus greatly to augment the momentum of 
the ball, ft is evident that this contributes, 
very much to the force of the explosion, by 
what happens when powder is wetted or mix- 
ed with any substance, which prevents it 
from taking lire all at once. In this case the 
force of the explosion, even when the same 
quantity of pow der is made use of, is not t« 
be compared with that of dry powder. 
We may conclude, upon these principles, 
that the force of an explosion depends. 1. on 
the quantity of elastic fluid to be expanded ; 
2. on the velocity it acquires by a certain 'de- 
gree of heat; and 3. on the celoritv with which 
the degree of heat affects the Whole of the 
expansile fluid. These three take place in 
the greatest perfection where the electric 
fluid is concerned, as in cases of lightning, 
earthquakes, and volcanoes. This fluid per- 
vades the w hole system of nature ; its expan- 
