593 
P L A 
and Jide-r dating plane. The plough is a narrow plane, 
provided with apparatus to guide ir, in moving ltraight, 
to plough a groove or trench at any required diftance from 
the edge of a board or other piece of wood, and to any 
depth or width. The dado grooving - plane is alfo for 
forming grooves. 
Planes for producing flat furfaces in metals have been 
brought into ufe within thefe few years paft, to the great 
improvement of the work of thofe artills who employ 
them. Thefe are chiefly the mathematical inftrument- 
makers, who are in the conftant habit of having to make 
ltraight rulers in brafs, and prepare work requiring very 
flat furfaces, fuch as the limbs of fextants, &c. but all 
trades which work in brafs and iron would find their 
advantage in employing the plane. The flock of this 
plane is ufually made of cafl-iron, in form of a hollow 
box, the bottom, fides, and ends, being all call in one 
piece; it is ufually is inches in length, if in height, 
and i| in breadth acrofs the face ; the iron is fituated at 
about four inches from the fore end, not inclined, as in 
other planes, but held in a perpendicular direction, with 
its lower or cutting edge palling through the mouth, and 
prcjeffing the lealt poflible quantity beneath the furface 
of the face, but leaving only fo fmall a fpace before the 
edge for a mouth, as will jufl admit a piece of thick 
paper; the iron is held againfl a brafs frame fixed acrofs 
in the hollow of the box or plane, and containing within 
it a fcrew, on which a nut or Aider is fitted, to rife and 
fall when the fcrew is turned round by a milled head 
upon the upper end of it; the nut or Aider has a pro¬ 
pping pin, which enters into a round hole made through 
vhe iron ; and in this cafe, by turning the fcrew, the iron 
is raifed or deprefied, to caufe the edge to protrude more 
or lefs beyond the face; to fupport this frame behind, a 
block of wood is fitted into the hollow of the flock, to 
fill up all the cavity, and it projects fo much above as to 
form the handle for the plane. In the front end of the 
flock, a fcrew is tapped through its thicknefs, and a6ts 
againfl a piece of wood, which it prefies up againfl the 
iron, and thus holds it fall: againfl the brafs frame, in the 
fame manner as the wedge of a common plane; this piece 
cf wood is formed forked and hollowed where it applies 
to the iron, to allow room for the chips to come up from 
the mouth. The woikmen who ufe this plane call it 
firiping, inflead of planing, brafs or other metal. 
The metal-plane is uled in the fame manner as a car¬ 
penter’s jack-plane; but, as the (having it cuts or rather 
fcrapes off muft be exceedingly thin, the greateft nicety is 
necefiary in adjufling the projection of the iron beyond 
the face ; and for this reafon the fcrew is eflential. The 
work is to be fupported upon a firm bench, which is beft 
made of cafl-iron, and the furface of it made perfectly 
fiat, which is done by grinding the face of the plane 
againfl it with emery, till both are true. The front face 
of the iron is quite flat, and perpendicular to the face ; 
the edge is formed at the bottom of tins furface by grind¬ 
ing a bevel from the back at an angle of about 45 degrees ; 
the edge is then made fine by a Turkey (tone. The 
•iron mull be exceedingly hard, and of the very beft fteel; 
and then the plane will cut loft flee], bell-metal, or caji- 
iron, as well as brafs, to very good purpole. When the 
work is rough, it is difficult fora man to work the plane, 
if let coarfe for expedition; they therefore ufe, in fuch 
cafe, an iron which is cut with flutes on the front fide, 
and then the edge will be divided into l'eparate teeth, 
which fcrape and cut away with lefs reiiftance than a com¬ 
plete edge. Meffrs. Holtzapfell and Deyedien, of Welt- 
minfter, make thefe planes for metal of exceedingly 
hard cafl-iron, and very true faces, which do not there¬ 
fore become fcratched or injured by wear. It fliould 
have, been mentioned before, that joiners, cabinet-makers, 
&c. in planing thin or valuable woods for veneering, See. 
fometimes ufe fluted irons, having teeth in their edge; 
and a plane thus mounted is called a toothing-plane 
ihefe irons apply to the flocks of different planes, 
PLANE, adj. Plain, even. 
VOL. XX. No. 1393. 
P L A 
To PLANE, v. a. To level; to fmooth; to free from 
inequalities.-r-The foundation of the Roman caufeway 
was made of rough ftone, joined with a moft firm cement; 
upon this was laid another layer of fmall (tones and 
cement, to plane the inequalities of rough ftone, in 
which the (tones of the upper pavement were fixt. Ar- 
buthnot on Coins. —To fmooth with a plane.—Thefe hard 
woods are more properly feraped than planed. Moxon .— 
To fly or hover, as a kite or other bird does, without 
moving its wings. 
PLANE, or Plane-tree, /. See Platanus. —The 
beech, the fvvimming alder, and the plane. Dryden .— 
The plane-tree hath an amentaceous flower, confilting of 
feveral (lender (tamina, which are all collected into fphe- 
rical little balls, and are barren; but the embryos of the 
fruit, which are produced on feparate parts of the fame 
trees, are turgid, and afterwards become large fpherical 
balls, containing many oblong feeds intermixed with 
down. It is generally fuppofed that the introduction of 
this tree into England is owing to the great lord-chan¬ 
cellor Bacon. Miller. 
PLA'NE-TREE, baftard or falfe, is a-name given to 
the maple. See Acer. 
PLA'NER, f. One who fmooths with a plane. A prin¬ 
ter’s inftrument, to level the types. 
PLANE'RA, f in botany. See Ulmus nemoralis. 
PLAN'ET, f. [planeta, Lat. from 7 rXcaiocu, Gr. to 
wander.]— Planets are the erratic or wandering ftars, and 
which are not like the fixt ones always in the fame pofi- 
tion to one another : we now number the Earth among 
the primary planets, becaufe we know it moves round the 
Sun, as Saturn, Jupiter, Mars, Venus, and Mercury, do, 
and that in a path or circle between Mars and Venus: 
and the Moon is accounted among the fecondary planets, 
or fatellites cf the primary, (ince (he moves round the 
Earth. All the planets have, befides their motion round 
the Sun, which makes their year, alfo a motion round 
their own axes, which makes their day; as the Earth 
revolving fo makes our day and night. It is more than 
probable that the diameters of ail the planets are longer 
than their axes : we know ’tis fo in our Earth; and 
Flamfteed and Caflini found it to be fo in Jupiter. Harris. 
—The Chaldeans were much devoted to aftrological devi¬ 
ces, and had an opinion that every hour of the day was go¬ 
verned by a particular planet, reckoning them according 
to their ufual order, Saturn, Jupiter, Mars, Venus, Mer¬ 
cury, Luna. Wilkins. 
And planets, planet-ftruck, real eclipfe 
Then fuffer’d.. t Milton’s P.L. 
Planets are ufually diftinguiflied into primary and 
fecondary. The primary, called alfo (imply, and by way 
of eminence, planets, are thofe which move round the 
Sun as their proper centre : fuch are the Georgium Sidus 
of Herfchel, Saturn, Jupiter, Vefta, Juno, Pallas, Ceres, 
Mars, the Earth, Venus, and Mercury. The fecondary 
are fuch as move round fome primary planet as their 
refpeCtive centre, in the fame manner as the primary 
planets do round the Sun. The Georgium Sidus, Saturn, 
Jupiter, and the Earth, are each attended with fecondary 
planets; the Georgian with 6, Jupiter with 4, and Sa¬ 
turn with 7, called the fatellites of thofe planets ; the 
Earth has one fecondary planet, called the Moon. 
The number of planets know n to the Chinele is five, 
which correfponds to that of the elementary lubftances 
they fuppofe to enter into the compofition of all bodies; 
namely, fire, water, earth, wood, and metal, over each 
of which a planet is fuppofed to prelide. Few of the 
Chinefeleem to have any idea of the earth’s motion; but 
imagine that the fun moves through the fixed ftars. 
Four points in his courfe along the yellow road (fo they 
call the ecliptic) are particularly diftinguiflied, as mark¬ 
ing the four feafons of the year. The day is divided by 
them, as by the ancient Egyptians, into twelve parts only, 
confuting each cf two European hours; the firft begin¬ 
ning at eleven at night. 
7 M 
We 
