N E R 
N E P 
spaces on the top are not divided, AFo there 
is a rod of digits, not divided, which is called 
the index- rod ; and of this we need but one 
single rod. See the figure of all the different 
rods, and the index, separate from one an- 
other, in plate Misccl. fig. 174. 
Neper’s rod, multiplication by. hirst lav 
down the index-rod; then on the right of it 
set the rod whose top is the figure in the 
highest place of the multiplicand ; next to this 
again set the rod whose top is next the figure 
of the, multiplicand ; and so on in order to the 
first figure. Then is your multiplicand tabu- 
lated for all the nine digits ; for in the same 
line of squares standing against every figure 
of the index-rod, you have the product of 
that figure, and therefore you have no more 
to do than to transfer the products and sum 
them. But in taking out these products from 
the rods, the order in which the figures stand 
obliges you to a very easy and small addition ; 
thus, begin to take out the figure in the lower 
part, or unit’s place, of the square of the first 
rod on the right; add the figure in the upper 
part of this rod to that in the lower part of 
the next, and so on, which may be done as 
fast as you can look on tnem. lo make this 
practice as clear as possible, take the follow- 
ing example. 
Example: To multiply 4768 by 385. Ilav 
ing set the rods together for the number 4768, 
against 5 in the index I find this numbei, by 
■ adding according to the rule - 23840 
Against 8 this number - - 38144 
Against 3 this number - - 14304 
Total product 
N E R 
2 GO 
1835680 
To make the use of the rods yet more regular 
and easy, they are kept in a flat square box, 
whose breadth is that of ten rods, and the 
length that of one rod, as thick as to hold six 
(or as many as you please) ; the capacity of 
the box being divided into ten cells, foi the 
different species of rods. M hen the rods aie 
put up in the box (each species in its own cell 
distinguished by the first figure of the rod set 
before it on the face of the box near the top), 
as much of every rop stands without the box 
as shews the first figure of that rod : also upon 
one of the flat sides without and near the 
edge, upon the left hand the index-rod is fix- 
ed'; and along the foot there is a small ledge, 
so that tiie rods when applied are laid upon 
this side, and supported by the ledge, .which 
makes the practice very easy ; but in case the 
multiplicand should have more than 9 places, 
the upper face of the box may be made 
broader. Some make the rods with four dif- 
ferent faces and figures on each for different 
purposes. _ 
Neper’s rods, division by. F irst tabulate 
your divisor ; then you have it multiplied by 
all the digits, out of which you may choose 
such convenient divisors as will be next less to 
the figures in the dividend, and wiite the in- 
dex answering in the quotient, and so conti- 
nually till the work is done. I bus 21/9/ 
divided by 6123, gives in the quotient 356 
11 a v frig tabulated the divisor, 6123, you 
see that 6 123 cannot be had in 2179; there- 
fore take five places, and on the rods find a 
number that is equal, or next less, to 21/97, 
which is 18369; that is 3 times the divisor, 
wherefore set 3 in the quotient, and subtiact 
18369 from the figures above, and there will 
remain 3428 ; to which add 8, the next figure 
of the dividend, and seek again on the rods 
lor it, or the next less, which you will find to 
be five times; therefore set 5 in the quotient, 
and subtract 30615 from 34288, and there 
will remain 3673 ; to which add 8, the last 
figure in the dividend, and finding it to be just 
6 times the divisor, set 6 in the quotient. 
NEl’ETA, Catmint, or Nep, a genus of 
the gymnospermia order, in the didynamia 
class of plants; and in the natural method 
ranking under the 42 d order, verticiliatax 
1 he under lip of the corolla has a small mid- 
dle segment crenated; the margin of the 
throat is reilexed ; the stamina approach one 
another. There are 20 species; the most 
remarkable is the cataria, common nep, or 
catmint. This is a native of many parts of 
Britain, growing about hedges and in waste 
places. The plant has a bitter taste, arid 
strong smell, not unlike pennyroyal. An in- 
fusion of this plant is reckoned a good ce- 
phalic and emmcnagogue ; being found very 
efficacious in chlorotic cases, i wo ounces of 
the expressed juice may be given lor a dose. 
It is called catmint, because cats are very fond 
of it, especially when it is withered ; tor then 
they will roll themselves on it, and tear it to 
pieces, chewing it in their mouths with great 
pleasure. 
NEPHELIUM, a genus of the pentandria 
order, in the monoecia class of plants. The 
male calyx is quinquedentate ; there is no co- 
rolla : the female calyx is quadrifid; there is 
no corolla. There are two germens and two 
styles on each: the fruit are two dry plumbs, 
muricated, and monospermous. 1 here is one 
species, a herb of the East Indies. 
NEPHRITIC WOOD, lignum nephriti- 
cum, a wood of a very dense and compact 
texture, and of a fine grain, brought us from 
New Spain, in small blocks, in ils natural 
state, and covered with its bark. It is to be 
chosen of a pale colour, sound and firm, and 
such as has not lost its acrid taste; but the 
surest test of it is the infusing it in water ; lor a 
piece of it infused only hall an hour in cold 
water, gives it a changeable colour, which is 
blue or yellow, as variously held to the light. 
If the phial it is in is held between the eye and 
the light, the tincture appears yellow; but if 
the eye is placed between the light and the 
phial, it appears blue. 
'Phis wood is a very good diuretic, and is 
said to be of great use with the Indians in all 
diseases of the kidneys and bladder, and in 
suppressions of urine irom whatever cause. 
It is also commended in fevers and obstruc- 
tions of the viscera. The way of taking it, 
among the Indians, is only an infusion in cold 
water. 
NEPHRITIS. See Medicine. 
NEREIS, in zoology, a genus of animals 
belonging to the order ot vermes moll use a. 
The body is oblong, linear, and fitted for 
creeping ; it is furnished with lateial pencilled 
tentacula. There are 11 species, ot which 
the most remarkable are the five following: 
1. The noctiluca, or noctilucous nereis, which 
inhabits almost every sea, and is one of the 
causes of the luminousness ot the water. 
These creatures shine like glow-worms, but 
with a brighter splendour, so as at night to 
make the element appear as if on fire all 
around. Their bodies are so minute as to 
elude examination by the naked eye. 
It is sometimes called nereis phosphorans ; 
and is thus described by Griseline. i he head 
is roundish and flat, and the mouth acumi- 
nated. The two horns or feelers are short 
and subulated. The eyes are prominent, and 
placed on each side of the head. The body 
is composed ot about twenty-three segments 
or joints, w hich are much less nearer the tail 
than at the head, dbese segments' on both 
sides the animal all end in a short conical 
apex, out of which proceeds a little bundle 
of hairs ; from under these 'bundles the iect 
grow in the form of small flexile subulated 
figments destitute of any thing like claws. 
It is scarcely two lines long, and is quite 
pellucid, and its colour is that of wafer, 
green. They are found upon all kinds of 
marine plants; but they often leave them, and 
are found upon the surface of the water : they 
are frequent at all seasons, but especially in 
summer before stormy weather, when they 
are more agitated and more luminous. r l heir 
numbers, and wonderful agility, added to 
their pellucid and shining quality, do not a 
little contribute to their illuminating the sea, 
for myriads of those animalcule may be con- 
tained in the portion of a small c up of sea- 
water. Innumerable quantities of them lodge 
in the cavities of the scales of fishes, and to 
them probably do the fishes owe their nocti- 
lucous qualitity. 
2. Nereis lacustris, or bog nereis (fig. 2.) 
The body of the size of a hog’s short bristle, 
transparent, articulated, and on either side at 
every articulation provided with a short seta- 
ceous foot; interiorly it seems to consist in a 
manner of oval-shaped articulations, and a 
back formed by two lines bent backwards. 
It inhabits marshes abounding in clay, where 
it remains under ground, pushing out its 
other extremity by reason ot its continual 
motion. When taken out it twists itself up. 
Is frequent in Sweden. 
3. Nereis cirrosa, or waving nereis. The 
body is red, lumbriciform, with sixty-five 
notches, furnished on both sides with two rows 
of bristles. At each side of the head ten fila- 
ments, at the sides of the mouth many, twice 
as long as the former. It dwells in Norway, 
on rocks at the bottom of the sea. It vomits 
a red liquor, with which it tinges the water. 
See Plate Nat. Hist. fig. 294. 
4. Nereis cairulea, or blue nereis. It in- 
habits the ocean, w here it destroys the ser- 
pulaa and teredines, fig. 295. 
5. Nereis giganuea, or giant nereis, is a 
peculiar species of those large worms that 
make their way into decayed piles driven 
down into the sea, which they bore through 
and feed upon, whence they are called sea- 
worms, or nereis. From head to tail they 
are beset on either side with small tufts ter- 
minating in three points, which are like the 
fine hair-pencils used by painters, and com- 
posed of shining bristles of various colours. 
The upper part of the body in this worm js 
all over covered with small hairs. The rings 
of which it is formed are closely pressed to- 
gether, and yield to the touch. The three 
rows of small tufts we have been describing, 
serve this nereis instead of feet, which it uses 
to go forwards as fishes do their fins. Fig. 296. 
N ERITA, a genus of vermes testacea : the 
generic character is; animal a Umax; shell 
univalve, spiral, gibbous, tiattish at bottom; 
aperture semiorbicular or semilunar; pillar- 
lip transversely truncate, flatfish. There are 
about 80 species of this genus. 
NERIUM, a genus of the monogynia 
order, in the pentandria class of plants, and in 
the natural method ranking under the 30th 
