a;o n e vr 
order, contorts*. There are two erect folli- 
cles; the seeds plumy ; the tube of the co- 
rolla terminated by a lacerated crown. There 
are nine species, all of them natives of the 
warmer climates ; the most remarkable of 
which are, 1 . 1 he oleander, South Sea rose ; 
this is a beautiful shrub, cultivated in gardens 
on account ot its flowers, which are of a fine 
red, and in clusters, but of an indifferent 
smeii ; the whole plant is poisonous, and es- 
pecially the bark of the roots. The double 
variety is beautiful, but it should be kept in a 
stove. 2.1 he antidysinteriunn, a native of 
Ceylon ; the bark of which is an article of the 
matei ia medica, under the name of conessi. 
3. 1 he tinctorium, a new species, with beau- 
tiful blue flowers, discovered by Dr. Rox- 
burgh at Madras. A decoction of the leaves, 
v itn an addition of lime-water, makes an in- 
digo of fine quality. The whole plant in all 
tlie neriums is of a poisonous quality, in that 
Tespect resembling apocynum. 
hR r l ERIA, a genus of the class and or- 
der tetrandria digynia; t lie corolla is funnel- 
shaped, four cleft ; superior berry two-celled ; 
seeds solitary. There is one species, an an- 
nual ot New Zealand. 
NERVES. See Anatomy. 
NRSi ORJANS, a Christian sect, the fol- 
lowers of Nestorius, bishop and patriarch of 
Constantinople; who, about the year 429, j 
taught that there were two persons in Jesus * 
Christ, the divine and the human, which are 
united, not hypostatically or substantially, 
but in a mystical manner: whence he con- 
cluded, that Mary was the mother of Christ, 
and not the mother of God. For this opi- 
nion Nestorius was condemned and deposed 
bv the council of Ephesus; and the decree of 
this council was confirmed by the emperor 
'] heodosius, who banished the bishop to a 
monastery. 
nettings, in a ship, a sort of grates 
made ot small ropes, seized together wit h rope- 
yarn or twine, and fixed on the quarters and in 
the tops ; they are sometimes stretched upon 
the ledges from the waste-trees to the roof- 
trees, from the top of the forecastle to the 
poop-; and sometimes are laid in the waste of 
a ship to serve instead of gratings. 
N El TLE. See Uktica. 
Nettle, dead. See Lamium. 
N EU RADA, a genus of the decagynia or- 
der, in thedecandria class of plants, arid in the 
natural method ranking under the 13th or- 
der, succulent®. The calyx is quinquepar- 
tite; there are five petals ; the capsule infe- 
rior, decern locular, decaspermous, and acu- 
leated. There is only one species, the pro- 
cumbens. The whole plant is white and 
woolly; and is a native of the warm climates, 
and found on dry parched grounds. 
NEUTRAL SALTS, among chemists, a 
sort of salts neither acid nor alkaline, but 
partaking of the nature of both. See Acid, 
Alkali, Chemistry, & c. 
NEUTRALIZATION. When two or 
more substances mutually destroy each other’s 
properties, they are said to neutr.dize one an- 
other. Thus, in a proper combination of 
acid and alkaline substances, the acid and 
alkaline properties are destroyed. 
NEWEL. See Architecture. 
NEWT. See Lacerta. 
N EWTONIAN PHILOSOPHY, thedoc- 
trirce of the universe, or the properties, laws, 
affections, actions, forces, motions, &c. of 
N E W 
bodies, both celestial and terrestrial, as de- 
livered by Newton. 
I he chief parts of the Newtonian philoso- 
phy, as delivered by the author, except his 
Optical. Discoveries, &c. are contained in his 
1 1 incipia, or Mathematical Principles of Na- 1 
tuie.i Philosophy. He founds his system on 
the following definitions. 
1. Quantity of matter is (lie measure of 
the same, arising from its density and bulk 
conjointly. 1 hus, air of a double density, in 
the same space, is double in quantity; 'in a 
double space, is quadruple in quantity; in a 
triple space, is sextuple in quantity, See. 
2 . Quantity of motion is the measure of 
the same, arising from the velocity and quan- 
tify of matter conjunctly. 1 his is evident, be- 
cause the motion or the whole is the motion 
of all its parts; and therefore in a body double 
in quantity , with equal velocity, the motion 
is double, &c. 
o. 1 he vis insifa, vis inertia*, or innate force 
of matter, is a power of resisting, by which 
every body, as much as in it lies, endeavours 
to persevere in its present state, whether it 
is of rest, or moving uniformly, forward in a 
right line. I his definition ia proved to be 
just, by experience, from observing the diffi- 
cult) w ith which any body is moved out of 
its place, upwards or obliquely; or even 
downwards, when acted on bv a body endea- 
vouring to urge it quicker than the 'velocity 
given it by gravity, and any how to change 
its state of motion or rest. And therefore 
this force is the same, whether the body has 
giavity or not ; and a cannon-ball, void of 
gravity, if it could be, being discharged ho- 
rizontally, will go the same distance in that 
duection, in the same time, as if it were en- 
dued with gravity. 
4. An impressed force is an action exerted 
upon a body, in order to change its state 
whether of rest or motion. This force con- 
sists in the action only ; and remains no longer 
in the body when the action is over. Fo^ a 1 
body maintains every new state it acquires I 
by its vis inertia: only. 
5. A centripetal force is that by which bo- 
dies ai e drawn, impelled, or any way tend, 
towards a point, as to a centre. This may 
be considered of three kinds, absolute, acce- 
lerative, and motive. 
6. i lie absolute quantity of a centripetal 
force is a measure of the same, proportional 
to the efficacy of the cause that urges it to 
the centre. 
7. The accelerative quantity of a centri- 
petal force, is the measure of the same pro- 
poitional to the velocity which it generates in 
a given time. 
8. The motive quantity of a centripetal 
toice, is a measure of the same, proportional 
to the motion which it generates in a given 
time. T iiis is always known by the quantity 
°t force equal and contrary to it, that is just 
sufficient to hinder the descent of the body. 
After these definitions, follow certain sciio- 
• ia, treating of the nature and distinctions of 
fane, space, place, and motion, absolute, rela- 
tive, apparent, true, real, &c. Afterwhieh, the 
uutnor proposes to shew how we are to collect 
the true motions from their causes, effects, 
•in 1 apparent ditferences ; and vice vers'd, 
now, from the motions, either true or appa- 
rent, we may come to the knowledge of their 
causes ami effects. In order to this, he lays 
down the following axioms or laws of motion, 
8 
N E W 
| ! ?t law. Every body perseveres in its state 
j oi rest, or of uni.orm 'motion in a right fine, 
j unless it is compelled to change that state by 
toices impressed upon it. 1 hus, “ projec- 
tiles pers verein their motions, so far as they 
a: e not retarded by the resistance ot the air, 
or impelled downwards by the fo.ee of gra- 
vity- A top, whose parts, by their cohesion, 
are perpetually drawn aside from rectilinear 
motions, does not cease its rotation otherwise 
than as it is retarded by the air. The greater 
bodies ot the planets and comets, meeting 
with less resistance in more free spaces, pre- 
serve their motions, both progressive and cir- 
cular, tor a much longer time.” 
2d law. lire alteration ot motion is always 
proportional to tire motive force impressed, 
and is made in the direction of the right line 
in which that force is impressed. Thus, if any 
force generates a certain quantity of motion, 
a double force will generate a double quan- 
tity, whether that force is impressed all at 
once or in successive moments. 
3d law. J o every action there is always 
opposed an equal re-action ; or the mutual 
actions of two bodies upon each other, are al- 
ways equal, and directed to contrary parts. 
1 hus, whatever draws or presses another, is 
as much drawn or pressed by that other. If 
you press a stone with your finger, the finger 
is also pressed by the stone, &c. 
from this axiom, or law, Newton deduces 
the follow ing corollaries : 
1. A body by two forces conjoined will 
describe the diagonal of a parallelogram, in 
the same time that it would describe the sides 
by those forces apart. 
2. Hence is explained the composition of 
any one direct force out of any two oblique 
ones, viz. by making the two oblique forces 
the sides of a parallelogram, and the diagonal 
the direct one. 
3. i he quantity of motion, which is col- 
lected by taking the sum ot the motions di- 
rected towards the same parts, and the differ- 
ence of those that are directed to contrary 
parts, suffers no change from the action of bo- 
dies among themselves; because the motion 
which one body loses is communicated to 
another. 
4. 1 he common centre of gravity of two 
oi more bodies does not alter its state of mo- 
tion or rest by the actions of the bodies 
among themselves; and therefore the com- 
mon centre of gravity of all bodies, acting 
upon each other, (excluding external actions 
and impediments) is either at rest, or moves 
uniformly in a right line. 
5. i he motions of bodies included in a 
given space are the same among themselves, 
whether that space is at rest, or moves uni- 
foimly forward in a right line without any 
circular motion. The truth ot this is evident 
from the experiment of a ship ; where all mo- 
tions are just the same, whether the ship is at 
rest, or proceeds uniformly forward in a 
straight line. 
(>. If bodies, any how moved among them- 
selves, are urged in the direction of parallel 
lines bv equal accelerative forces, they will 
all continue to move among themselves, after 
the same manner as if they had not’ been 
urged by such forces. 
1 lie mathematical part of the Newtonian 
1 hilosophy depends chiefly on the following 
lemmas, especially the first, containing the 
doctrine of prime and ultimate ratios. 
