E T H 
E V A 
EVA 657 
systems of ethics, or lectures on moral phi- 
losophy ! On this account we have made this 
article very short, and given rather the opi- 
iiians of others than our own, merely So shew 
(as matter of information) what has been said 
and thought upon the subject. 
Before we conclude this article, it will be 
roper to say something of the extraordinary 
ypothesis of Hobbes, concerning the foun- 
dation of morality. This philosopher, who 
gaw his country involved in all the distraction 
and misery of a civil war, seems to have 
taken too narrow and partial a view of our 
nature, aud has therefore drawn it in a very 
odious and uncomfortable light. Next to 
the desire of self-preservation, he makes the 
love of glory and of power to be the govern- 
ing passions* in man; and from these, by an 
arbitrary, unnatural, and unsupported hypo- 
thesis, contrary to common experience and 
common language, he attempts to deduce 
all the other passions which inflame the 
minds and influence the manners of men. 
According to him all men are equal, all de- 
sire and have a right to the same things, and 
want to excel each other in power and ho- 
nour ; but as it is impossible for all to possess 
the same things, or to obtain a pre-emi- 
nence in power and honour, hence must arise 
a state of war and mutual carnage ; which is 
what he calls a state of nature. But this 
shrewd philosopher subjoins, that men being 
aware that such a stale must terminate in 
their own destruction, agreed to surrender 
their private unlimited right into the hands 
of the majority, or such as the majority 
should appoint, and to subject themselves for 
the future to common laws or to common 
judges or magistrates. In consequence of 
this surrender, and of this mutual compact or 
agreement, they are secured against mutual 
hostilities, and bound or obliged to a peace- 
able behaviour ; so that it is no longer lawful 
or just (he certainly means safe or prudent) 
to invade and incroach on one another, since 
this would be a violation of his promise. But 
one may ask him, what obligation is a man 
under to keep his promise or stand to his 
compact, if there is no obligation, no moral 
tie, distinct from that promise ? On the whole, 
his state of nature is a mere chimera, and the 
superstructure he has raised on it no less so. 
ETHER. See ./Ether. 
ETHMOIDAL, in anatomy, one of the 
common sutures . of the skull, which goes 
round the os ethmoides, from which it de- 
rives its name, separating it from the bone in 
contact with it. 
ETHNOPHRONES, in church history, 
a sect of Christians of the seventh century, 
who, professing Christianity, joined to it all 
the ceremonies and follies of Paganism, such 
as judicial astrology, divinations of all kinds, 
&c. and who observed all the feasts, times, 
and seasons, of the Gentiles. 
ETIIOPOEIA, or Ethology, in rheto- 
ric, a draught or description, , expressing the 
manners, passions, genius, tempers, aims, 
See. of any person. Such is that noted pic- 
ture of Catiline, as drawn by Sallust : fait 
magna r i dy animi, Sec. “ He was a man of 
great vigour both of body and mind; but of 
a disposition extremely profligate and deprav- 
ed. From his youth he took pleasure in ci- 
vil wars, massacres, depredations, and intes- 
tine broils; and in these he employed his 
Vol. I, 
younger days. His body was formed fbr 
enduring cold, hunger, and want of rest, to a 
degree indeed incredible : his spirit was dar- 
ing, subtle, and changeable; lie was expert 
in all the arts of simulation and dissimula- 
tion, covetous of what belonged to others, 
lavish of his own, violent in his passions: he 
had eloquence enough, but a small share of 
wisdom ; his boundless soul was constantly 
engaged in extravagant and romantic pro- 
jects, too high to be attempted.” 
ETHULIA, a genus of the class and order 
syngenesia polygamia lequalis. The recep- 
tacle is naked ; down none. There are six 
species, chiefly annuals of the East Indies. 
ETHUSA, fool’s parsley. See JEthusa. 
ETNA. See Volcano. 
El YMOLOGY, that part of grammar 
which considers and explains the origin and 
derivation of words, in order to arrive at their 
lirst and primary signification, whence Quin- 
tilian calls it originatio. 
The best treatise on the etymology of 
English words, and for the ascertaining of 
their force and usage, is unquestionably the 
Epea Pteroenta of Mr. Horne Took©, already 
quoted in this work. 
EVACUANTS. See Materia Medica. 
EV ANTES, in antiquity, the priestesses 
. of Bacchus, thus called, because in celebrat- 
ing the orgia, they ran about as if distracted, 
crying, evan, evan, ohi evan. 
EVAPORATION, in chemistry, the set- 
ting a liquor in a gentle heat or in the air, to 
discharge its superfluous humidity, reduce it 
to a proper consistence, or obtain its dry re- 
mainder. 
Evaporation, though generally considered 
as the effect of the heat and motion of the 
air, may he produced by a different cause. 
Fluids lose more by evaporation in the se- 
verest frost than when the air is moderately 
warm. Thus, in the great frost of 1708, it 
was found that the greater the cold the more 
considerable the evaporation. Ice itself loses 
much by evaporation. 
Evaporation, in natural philosophy, is 
the conversion of water into vapour, which in 
consequence of becoming lighter than the at- 
mosphere, is raised considerably above the sur- 
face of the earth, and afterwards by a partial 
condensation forms clouds. It differs from 
exhalation, which is properly a dispersion of 
dry particles from a body. 
We are indebted to the experiments of 
Saussureand Deluc for much of our know- 
ledge of the qualities of vapour. It is an 
elastic invisible fluid like common air, but 
lighter ; being to common air of the same 
elasticity, according to Saussure, as 10 to 14, 
or, according to Kirwan, as 10 to 12. 
When water is heated to 212°, it boils, and 
is rapidly converted into steam; and the same 
change takes place in much lower tempera- 
tures ; but in that case the evaporation is 
slower, and the elasticity of the steam is 
smaller. As a very considerable proportion 
of the earth’s surface is covered with water, 
and as this water is constantly evaporating 
and mixing with the atmosphere in the slate 
of vapour, a precise determination of the rate 
of evaporation must be of very great impor- 
. tance in meteorology. Accordingly, many 
experiments have been made to. determine 
the point by different philosophers. No per- 
son has succeeded so completely as Mr. JDal- 
40 
ton : but many curious particulars had been 
previously ascertained by the labours of 
Richman, Lambert, Wallerius, Leidenfrost, 
Watson, Saussure, Deluc, Kirwan, and 
others. 
1. The evaporation is confined entirely' to 
the surface of the water: hence it is in all 
cases proportional to the surface of the water 
exposed to the atmosphere. Much mor • 
vapour of cOurse rises in maritime countries, 
or those interspersed with lakes, than in in- 
land countries. 
2. Much more vapour rises during hot: 
weather than during cold: hence the quan- 
tity evaporated depends in some measure 
upon temperature. The precise law has 
been happily discovered by Mr. Dalton. 
This philosopher took a cylindrical vessel of 
tin, whose diameter was 3l inches, and its 
depth 2 k inches, filled it with water, and kept 
it just boiling for some time. The. loss of 
weight in the minute was 30 grains, when the 
experiment was made in a close room with- 
out any draught of air ; 35 grains when the 
vessel was placed over lire in the usual fire- 
place, there being a moderate draught of 
air, and the room close ; 40 with a brisker 
fire and a stronger draught ; and when the 
draught was very strong, he supposes the 
evaporation might amount to 60 grains in the 
minute. At the temperature of 180°, the 
quantity evaporated was one half of what was 
lost at 2 12°. 
At 164° it was l of that at 212*. 
152 | 
144 \ 
138 <. 
And in general the quantity evaporated - from 
a given surface of water per minute at any 
temperature is to the quantity evaporated, 
from the same surface at 212°, as the force of 
vapour at the first temperature is to the force 
of vapour at 212'’. Hence, in order to discover 
the quantity which will be lost by evapora- 
tion from water of a given temperature, we 
have only to ascertain the force of vapour at 
that temperature. Hence we see that the 
presence of atmospheric air obstructs the 
evaporation of water; but this evaporation 
is overcome in proportion to the force of the 
vapour. Mr. Dalton ascribes this obstruc- 
tion to the vis inertial of air. 
3. The quantity of vapour which rises from 
water, even when the temperature is the 
same, varies according to circumstances. It 
is least of all in calm weather, greater when a 
breeze blows, and greatest of all with a strong 
wind. The following table, drawn up by Mr. 
Dalton, shews the quantity of vapour raised 
from a circular surface of six inches in dia- 
meter in atmospheric temperatures. The 
first column expresses the temperature ; the 
second the corresponding force of vapour; 
the other three columns give the number of 
grains of water that would be evaporated 
from a surface of six inches in diameter in 
the respective temperatures, on the suppo-i 
sition of there being previously -no aqueous 
vapour in the atmosphere. These column's 
present the extremes and the mean of evapo- 
ration likely to be noticed, or nearly such ; 
for the lirst is calculated upon the supposition 
of 35 grains loss per minute from the vessel 
of 3k inches in diameter; the second 45, and 
the third 55 grains per minute. 
