ACT 
driacal and radiated. There are five fpecies, fome of 
which make a beautiful appearance, and are called animal 
flowers, fea anemonies, and urtica marina. 
Progreflive motion in thefe creatures is fo flow, that it is 
difficult to perceive any, as they fcarce advance the length 
of one inch in an hour. It would feem they do not all pro¬ 
duce, when handled, the painful fenfation which had ac¬ 
quired them the name of fea-nettles.—They are vivipa¬ 
rous, feed on fhell-fiih, open their mouth more or lefs ac¬ 
cording to the fize of the prey they have to deal with, and 
then reject the (hell through the fame aperture. When 
the mouth is open, all the tentacula of the aftinia may be 
feen, refemblingin that fituation a full-blown flower, which 
has given it the denomination of the flower fifh. 
ACTIO, in Roman antiquities, an aftion at law in a 
court of juftice. The formalities ufed by the Romans, in 
judicial actions, werethefe: If the difference failed to be 
made up by friends, the injured perfon proceeded in jus 
reum vocare, to fummon the offending party to the court, 
who was obliged to go, or give bond for his appearance. 
The offending party might be fummoned into court viva 
voce, by the pdaintiff himfelf meeting the defendant, de¬ 
claring his intention to him, and commanding him to go 
before the magiftrate and make his defence. If he would 
not go willingly, he might drag and force him along, un- 
lefs he gave fecurity for his appearance on fome appointed 
day. Both parties being met before the praetor, or other 
fupreme magifirate prefiding in the court, the plaintiff 
propofed the action to the defendant; in which he de- 
figned to profecute him. This they termed edere aElionem ; 
and was commonly performed by writing it in a tablet, and 
offering it to the defendant, that he might fee whether he 
had better fiand the fuit or compound. In the next place 
came the pojlulatio aElionis, or the plaintiff’s petition to the 
praetor, for leave to profecute the defendant in fuch an 
aftion. And, the petition being granted, the plaintiff'obli¬ 
ged him to give fureties for his appearance on fuch a day 
in the court; when, upon the non-appearance of either 
party, the defaulter loff his caufe ;—if they both appear¬ 
ed, they were faid fe fetiffe-, and then the plaintiff pro¬ 
ceeded litem five aEhonon intendere, i. e. to prefer his fuit, 
which was done in a fet form of words, varying according 
to the difference of the aftions. After this the plaintiff 
defired judgment of the praetor, that is, to be allowed a 
judex or arbiter , or elfe the recuperatores or centumviri. 
Thefe he requefted for the hearing and deciding the buii- 
nefs ; but none of them could be defired but by the con- 
fent of both parties. 
The praetor having affigned them their judges, defined 
and determined the number of witneffes to be admitted, 
to hinder the protrad'ting of the fuit; and then the parties 
proceeded to give their caution, that the judgment, what¬ 
ever it was, fhould ftand and be performed on both fides. 
The judges took a foletnn oath to be impartial; and the 
parties took the juramentum calumnice. Then the trial be¬ 
gan with the afliftance of witneffes, writings, &c. which 
was called dfeeptatio caufx. 
ACTION,/! \_aElion, Fr. aElio, Lat.] The quality or 
ffate of afting, oppofite to ref; 
O noble Englifh ! that could entertain 
With half their forces the full power of France; 
And let another half fiand laughing by, 
All out of work, and cold for aEiion. Shakefpeare. 
An aft or thing done; a deed. Agency, operation. The 
feries of events reprefented in a fable. Gefficulation, the 
accordance of the motions of the body with the words 
fpoken; a part of oratory.—Our orators are obferved to 
make ufe of lefs gefture or atlion than thole of other 
countries. Addifon. 
Action, in mechanics, implies either the effort which 
a body or power makes againft another body or pow er, or 
the effect itfelf of that effort. As it is neceffary in works 
of this kind to have a particular regard to the common 
language of mechanics and philofophers, we have given 
Vol. I. No. 7. 
ACT roi 
this double definition: but the proper fignification of the 
term is the motion which a body really produces, or tends 
to produce, in another ; that is, fuch is the motion it wouid 
have produced, had nothing hindered its effeft. 
All power is nothing more than a body aftually in mo¬ 
tion, or which tends to move itfelf; that is, a body which 
would move itfelf if nothing oppofed it. The-ad'tion 
therefore of a body is rendered evident to us by its motion 
only; and confequently we muff; not fix any other idea to 
the word aftion, than that of aftual motion, or a Am¬ 
ple tendency to motion. The famous queltion relating to 
vis viva, and vis mortua , owes, in all probability, itsexiff- 
ence to an adequate idea of the word action; for, had 
Leibnitz and his followers obferved, that the only precife 
and diffinft idea we can give to the word force or aftion, 
reduces it to its effeft, that is, to the motion it aftually 
produces or tends to produce, they would never have made 
that curious diftinftion. 
Quantity of Action, a name given by M. de Mauper- 
tuis, in the Memoires of the Parifian Academy of Scien¬ 
ces for 1744, and thofe of Berlin for 1746, to theproduft 
of the mafs of a body by the fpace which it runs through 
and by its celerity. He lays it down as a general law,, 
“ that, in the changes made in the ffate of a body, the 
quantity of aftion neceffary to produce fuch change is the 
lead polfible.” This principle he applies to the invefti- 
gation of the laws of refraftion, of equilibrium, &c. and 
even to the ways of acting employed by the Supreme Be¬ 
ing. In this manner M. de Maupertuis attempts to con- 
neft the metaphyfics of final caufes with the fundamental 
truths of mechanics, to ffiew the dependence of the col- 
lifion of both elaftic and hard bodies upon one and the 
fame law, which before had always been referred to fepa- 
ratelaws; and to reduce the laws of motion, and thofe 
of equilibrium, to one and the fame principle. 
Action, in ethics, denotes the external ligns or ex- 
preflions of the fentiments of a moral agent. 
Action, in painting and fculpture, is the attitude or 
pofition of the feveral parts of the face, body, and limbs, 
of fuch figures as are reprefented^ and whereby they feem 
to be really aftuated bypaffions. Thus we fay, the aftion 
of fuch a figure finely expreffes the paflions with which it 
is agitated: we alfo ufe the fame expreflion with regard 
to animals. 
Action, in phyfiology, is applied to the funftions of 
the body, whether vital, animal, or natural.—The vital 
funftions, or aftions, are thofe which aie abfolutely ne¬ 
ceffary to life, and without which there is no life, as the 
aftion of the heart, lungs, and arteries. On the afttion 
and reaftion of the folids and fluids on each other, depend 
the vital funftions. The pulfe and refpiration are the ex¬ 
ternal figns of life. Vital difeafes are all thofe which hin¬ 
der the influx of the venous blood into the cavities of the 
heart, and the expulfion of the arterial blood from the 
fame.—The natural funftions are thofe which are inffru- 
mental in repairing the feveral Ioffes which the body fuf- 
tains ; for life is deffruftive of itfelf, its very offices occa- 
fioning a perpetual wafte. The manducation of food, the 
deglutition and digefiion thereof, alfo the feparation and 
diffribution of the chyle and excrementitious parts, &c. 
are under the head of natural funftions, as by thefe our 
aliment is converted into our nature. They aremeceffary 
to the continuance of our bodies.—The animal funftions 
are thofe which we perform at will, as mufcular motion, 
and all the voluntary aftions of the body: they are - thofe 
which conftitute the fenies of touch, taffe, Jmetl, fight, 
hearing; perception, reafoning, imagination, memory, 
judgment, affections of the mind. Without any or all 
of them, a man may live, but not fo comfortably as with 
them.—The aftions peculiar to thefexes are thofeof the or¬ 
gans of generation of either lex.— Private aftions are fuch 
as regard particular parts.— Public aftions are thofe which 
are performed for the fake of the whole body ; fuch is the 
aftion of the ftomach in digefting the aliment, &.c. Thefe 
are called funftions. But each part hath an action pecu- 
D d liar 
