Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/893

 MOO

MOMORDICA (Suppl.) — Stinking. Momordica, a name

ufed by fome for the large fruited white bryony of Ceylon. See the article Bryonia alba, Suppl. MONBIN, in botany, the name given by Plumier to a genus of plants, called by other botanifts Spoudias. See the article

SpONDIAS, Suppl.

MONEDULA, in ornithology, a name ufed by fome writers for the Jackdaw, a fpecies of Corvus. See the articles Cor- " vus, and Jackdaw, Suppl.

MONEY-tuflrf, the Englifh name of a diftinct genus of plants, known among botanifts by that of Nummularia. See the ar- ticle NuMMULARIA, Suppl.

MONK 1 's-rbubarb, the Englifh name of the broad-leaved gar- den Lapatbum, or dock. See the article Lapathum, Suppl.

MONKEY, in zoology, a name given by way of diftinct ion to thofe apes which have tails ; the others, or thofe without tails, being more properly called apes.

The fame diftindtion holds in latin, the tailed ones being called Cercopitbeci, and thofe without tails Simla:. See the articles Cercopithecus and Si mi A, Suppl.

Monkey, in the fea-language, a block made of iron, with a catch, ufed in gins for driving piles. Blanckley's Naval Ex- pofitor, p. 107.

MONOCEROS pifcis. Befides the two kinds of unicorn-fifh defcribed in the Supplement under the article Monoceros, there is another very large one of the fame genus. Sec the article Unicorn, Suppl.

MONOCULUS, in zoology, the name of a genus of infects, of the Podaria kind. See the article Podaria, append. Its body is fhort, of a roundifh figure, and covered with a firm cruffaceous fkin ; the fore legs are ramofe, and ferve for leaping and fw'miming. It has but one eye, which is large, and compofed of three fmaller ones.

Of this genus, many of which have been reckoned among the microicopic animals, authors enumerate a great number of fpecies ; for which fee Bill, Hift. Anim. p. 22.

MONORCHIS. Befide the common iignification of this word as the name of a plant, phyficians have alfo us'd it to exprefs a man who has but one tefiicle.

MONOTRIGLYPH, in architecture; denotes the fpace of one Triglyph, between two pillafters or two cslumns. Build. Dj&.'invoc. Seethe article Triglyph, Cycl.

MOON (Cycl.) — The path of the moon is concave towards the fun throughout.

In other fecondary planets, as the fatellites of the fuperior planets, that part of the path of thefe fatellites which is near- eft the fun, is convex towards the fun, and the reft is con- cave. And we often find in elementary treatrfes of aftro- nomy,the Moon's path reprefented in the fame manner; that is, as partly convex and partly concave towards the fun ; but this is a miftake. For it is to be obferved, in general, that the force which bends the courfe of the fatellite into a curve, when the motion is referred to an immoveable plane, is, at the conjunction, the difference of its gravity towards the fun, and of its gravity towards the primary. When the former prevails over the latter, the force that bends the courfe of the fatellite tends towards the fun ; and confequent- ly the concavity of the path is towards the fun ; and this is the cafe of the Moon. When the gravity towards the pri- mary exceeds the gravity towards the fun, at the conjunction, then the force that bends the courfe of the fatellite tends to- wards the primary, and therefore towards the oppofition of the fun ; confequently the path is there convex towards the fun ; and this is the cafe of the fatellites of Jupiter. When thefe two forces are equal, the path has, at the conjunction, what mathematicians call a point of rectitude ; in which cafe, however, the path is concave towards the fun throughout. The gravity of the Moon towards the fun having been found to be greater, at her conjunction, than her gravity towards the earth, fo that the point of equal attraction, where thofe two powers would fuftain each other, falls then between the Moon and earth, fome » have apprehended that either the parallax of the fun is very different from that which is affign'd by aftronomers, or that the Moon ought neceffarily to aban- don the earth. This apprehenfion may be removed eafily, by attending to what has been fhewn by Sir Ifaac Newton, and is illiiftrated by vulgar experiments concerning the mo- tions of bodies about one another, that are all acted upon by a third force in the fame direction. Their relative motions not being in the leaft 'difturbed by this third force, if it act equally upon them in parallel lines ; as the relative motion of the fhins in a fleet, carried away by a current, are noway affected by it, if it act equally upon them ; or as the rota- tion of a bullet or bomb, about its axis, while it is projected in the air ; or the figure of a drop of falling rain, are not at all affected by the gravity of the particles of which they are made up, towards the earth. It is to the inequality of the action of the fun upon the earth and Moon ; and the want of parallelifm in the directions of thefe actions, only, that we are to afcribe the irregularities in the motion of the Moon. [ a The ingenious Mr. Baxter, author of Matbo, or cofmo- theoria pueiilis.] APPEND.

MOT

But It may contribute towards removing this difficulty to ob- ferve, that if the abfolute velocity of the Moon, at the con- junction, was lefs than that which is requifite to carry a bodv' in a circle there around the fun, fuppofing this body to be acted on by the fame force which acts there on the Moon (i. e. by the excefs of her gravity towards the fun, above her gra- vity towards the earth* then the Moon would, indeed, aban- don the earth. For, in that cafe, the Moon having lefs velo- city than would be ueceflary to prevent her from defcending within that circle, fhe would approach to the fun, and recede from the earth. But tho' the abfolute velocity of the Moen t at the conjunction, be lefs than the velocity of the earth in the annual orbit, yet her gravity towards the fun is fo much diminjfhed by her gravity towards the earth, that her abfolute velocity is ftill much fuperior to that which is requifite to carry a body in a circle, there, about the fun, that is acted on by the remaining force only. Therefore, from the mo- ment of the conjunction, the Moon is carried without fuch a circle, receding continually from the fun to greater and greater diftances, till fhe arrives at the oppofition ; where being acted on by the ftim of thofe two gravities, and her velocity being now lefs than what is requifite to carry a body in a circle, there, about the fun, that is acted on by a force equal to that fum, the Moon thence begins to approach to the fun again. Tims, fhe recedes from the fun, and approaches to ■it by turns, and in every month her path hath two apfiae$ji a perihelium at the conjunction, and an aphclium at the op- pofition ; between which fhe is always carried in a manner fimilar to that in which the primary planets revolve between their apfides. The planet recedes from the fun at the perihe^ hum, becaufe its velocity, there, is greater than that with which a circle could be defcribed about the fun at the fame diftance by the fame centripetal force ; and approaches to- wards the fun from the aphelium, becaufe its velocity, there > is lefs than is requifite to carry it in a circle, at that diftance about the fun. See Mac Latirin's, Account of Sir Ifaac Newton's Phi!. Difc. Book 4. c. 5.

Moon-«w7, the Englifh name of a diftinct genus of plants, called by botanifts Lunaria. See the article Lunaria, Suppl.

NLoon -trefoil, a name by which the Meditago of botanifts 15 fometimes called. See the article Medicago, Suppl.

M.00K-feed, in botany, the Englifh name of a genus of plants, called by botanifts Menifpermum, See the article Menis- permum, Append.

MOOR-iaEaa^. See the article Buzzard, Suppl.

MOOTER, in the dock-yards, the perfon who forms ant! fmooths the tree-nails for ufe. Blanckky's Nav. Expofitor, p. 108.

MORBUS Hungarian, See the article Hungaricus morhus 9 Append.

MORDELLA, a name given by fome writers to the Ear^wig, See the article EaR-w^, Append.

Mordella, in zoology, the name of a genus of four-winged flies, diftinguifhed by having the laft joint of the antennae globofe ; moft of the fpecies have alfo legs for leaping. See the article Fly, Suppl.

Of this genus there are a great many fpecies, for which fee Hill, Rift. Anim. p. 49.

MORILLES, a kind of mufhroom, about the bignefs of a wallnut, pierced with holes like a honey- comb, and faid to be good for creating an appetite. They are alfo accounted reftorative, and frequently ufed in fauces and ragouts.

MORMYLU-S, in ichthyology, the name of a fpecies ot'Sparus* with the upper jaw longeft, and with twelve parallel, tranf- verfe black lines on each fide. See the article Sparus, Suppl.

MORTAR (Cycl.) — It is faid, that the fpherical figure is beft for the chamber of a mortar. Hift. Acad, Scienc. 1740.

But this propofition fcems doubtful. By fome experiments made before the Royal Society in 1742, it appeared, that the longeft cylindrical chambers of the fame capacity threw the ball fartheft ; which may give ground to fufpect that a long cylinder might be a better figure for the chamber of a Mortar than a fphere of equal capacity. See the article Gunnery,

Coeborn Mortar, a fmall kind of Mortar, invented by the fa- mous engineer baron Coehorn, to throw fmall fhells or granades. ThefeMortars are commonly fixed, to the number of a dozen, to a block of oak, at an elevation of 45 °.

MORTIFICATION, in medicine. Seethe articleSpHACE- lus, Cycl. and Suppl.

MOSCHUS, the mujk animal. See the articles'MoscHiFE- rum animal, and Musk, Suppl.

MOTH, in zoology, the Englifh name of a large clafs of but- terflies, comprehending all the nocturnal ones, or thofe which fly by night, and called PhaUnes by authors. See the article

I HALEN-ffi, Suppl. Mom-mullein, in botany, the Englifh name of a diftinct genus of plants, known among botanical writers by thatof.fi/etftf- ria. See the article Blattaria, Suppl.

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