Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/614

 DOC

D O D

dtnd, diftinguifhed by a point, in working by the rule of divifion.

DIVING (Cycl.)—DiviKG Bladder, a term ufed by Borelli for a machine, which he contrived for Diving under the water to great depths, with great facility, and prefers to the com- mon diving bell. The vefica, or bladder, as it is ufually called, is to be of brafs or copper, and about two foot in dia- meter. This is to contain the Diver's head, and is to be fixed to a goat's skin habit, exactly fitted to the fhape of the body of the perfon. Within this vefica there are pipes, by means of which a circulation of air is contrived ; and the per- fon carries an air pump by his fide, by means of which he may make bimfelf heavier or lighter, as the fifties do, by con- tracting or dilating their air bladder : by this means, the ob- jections all other diving machines are liable to are obviated, and particularly that of the air; the moifture by which it is clogged in refpiration, and by which it is rendered unfit for the fame Life again, being here taken from it by its circula- tion through the pipes, to the fides of which it adheres, and leaves the air as free as before. Borelli Opera Pufthuma.

DIUIOHU, in Botany, a name given by the people of Guinea to a fpecies of plant, with which they ufe to ripen and break boils, beating the leaves and laying them on.

DIVISIBILITY (C;- t 7.)--Di visibility a/magnitude.— All that is fuppofed, in ftrict geometry, concerning the Divifibility of magnitude, amounts to no more, than that a given magnitude may be conceived to be divided into a number of parts, equal to any given or propoled number. It is true, that the num- ber of parts, into which a given magnitude may be conceived to be divided, is not to be fixed or limited, becaufe no given number is fo great but a greater may be conceived and af- figned : but there is nor, therefore, any neceifity of fuppoimg the number of parts actually infinite ; and if fome have drawn very abflrufe confequences from fuch a fuppofkion, yet geo- metry ought not to be loaded with them. Mac Laurin's Fluxions, art. 290. See Extension.

DIVISION (Cycl.) — The fign of Divifien made ufe of in algebra, is fometimes a line drawn between the dividend or divifor,

thu. : —r ; fometimes the fign — - is placed between the two

quantities thus, a -=- b. Others, particularly the Germans, after Leibnitz, make ufe of two points only; thus, a ; b. All which equally fignify a divided by b.

Division, in rhetoric, the arrangement of a difcourfe under fe- veral heads, to be fpoken to feparately. Vojf. Rhet. 1. 3. p. 366. See Disposition, Cycl.

Division es, in antiquity, certain prefents of money, oil, bread, wine, or the like, appointed by will to be diftributed annually among certain perfons or companies, and fometimes to the people in general. Pitifc. Lex. Ant. in voc.

DIUTURNITY, the long continuance or duration of any being.

DIZOSTOS, in Botany, a name given by fome of the old Greek writers to the apios or knobby rooted fpurge: it is fo called, becaufe of its having ufually two or three flender, and rufh like ftalks, growing up from the roots, which feem as if they were fit to be ufed as cords or bandages. See the article Apios.

DO, In the Italian mufic, is a fy liable ufed inftead of a/, being fuppofed more refonant and mufical than ut. Brejjl Diet. Muf. in voc.

Do Law. To do law, facere legem-, is the fame as to make law, anno 23 Hen. 6. c. 14. Sec Make.

DOBCH1CK, in zoology, the common Englifh name of a fmall water fowl, the leaii of all the Diver kind, and known a- mong authors by the name of Colymbus minor. It feldom ex- ceeds fix ounces in weight, and has a fhort beak not more than a finger's breadth long, large at the bale, but taper- ing to a point at the end ; its eyes are large, and it is covered with a very thick downy plumage ; it is of a very deep black- ifh brown on the back, and very white on the belly ; its wings are very fmall, and it has no tail.

DOBULA, in ichthyology, a name given by Gefner, and other writers to the chubb. It has been called capita and cepha- lus by the moderns, andfqualus by the antients ; but it requires no generical name, being properly only a fpecies of the cypri- nus. See the articles Cephalus and Cyprinus.

Dobula is alfo ufed for a frefti water fifh, of the leucif- cus, or dace kind, but is of a larger and thinner fhape, and a much better tailed fifh. It is caught in the frefli waters of Germany about Hamburgh, and in many other places. Scbo- nefeldt Hift. pifc

POCIMASIA, Ao/,//x«<r/a, in antiquity, a cuftom among the Athenians, by which every man, before he was admitted to a public employment, was obliged to give an account of bim- felf, and his pad life, before certain judges in the forum ; for if any man had lived a vicious and fcandalous life, he was thought unworthy of the mcaneft office. Nor was this thought enough : for the fir ft ordinary allembly after their election, they

t were a ftgond time brought to the teft ; when, if any thing

fcandalous was found againfl them, they were deprived of thai honours. Pott. Archaeol. Grrec. 1. 1. c. 11. T. 1 p, 77

DOCIMASTICAL Experiments. See Assaying.

DOCIMENUM marmor, a name given by the antients to a fne- cies of marble, of a bright and clear white, much ufed in the large fumptuous buildings, as temples and the like. It bad it- name from Docimcnos, a city of Phrygia, afterwards called Synaia, near which it was dug, and from whence it was fent to Rome. It was accounted little inferior to the Parian in colour, but not capable of fo eleg.mt a polifh ; whence it was lefs ufed by the ftatuaries, or in other fmaller works. The Emperor Adrian is faid to have ufed this marble in building the temple of Jupiter, and many other of the great works of the Romans are of it.

DOCK {Cycl.) — DocK-rwr, in the materia medica. See the article Lapathi radix.

Dock, in the manege, is ufed for a large cafe of leather, as long as the Dock of a horfe's tail, which ferves it for a cover. The French call the Bosk, troujfequeue. It is made faft by ft raps to the crupper ; and has leathern thongs that pafs between his thighs, and along the flanks to the faddle ftraps, in order to keep the tail tight, and to hinder it to whisk about.

DoCK-Tardsy in {hip-building, are magazines of all forts of na- val ftores ; the principal ones in England, are thofe at Chat- ham, Portfmouth, Plymouth, Woolwich, Deptford, and Sheernefs. In time of peace, {hips of war are laid up in thefe Docks, thofe of the firft rates moftly at Chatham, where, and at other yards, tbey receive, from time to time, fuch repairs as are neceflary.

Thefe yards are generally fupplied from the northern crowns, with hemp, pitch, tar, rofin, and feveral other fpecies. But as for mails, particularly thole of the largeft fize, they are brought from New England.

How much it imports the good of the public, to keep thofe magazines confiantly replenished, everyone is able to judge: and it were much to be wifhed, the improving the fore-men- tioned commodities in our Englifh plantations, might meet with all poifible encouragement; left onetime or other, it may prove difficult to get them ellewhere. It is reafonable to think fuch an undertaking will put the nation to fome con- fiderable charge, ere it be brought to perfection ; but when fo, many are the advantages that will arife from it.

DOCTOR {Cycl) — A Doctor of the civil law may exercife ec- clefiaftical jurifdiction, though a layman. Stat. 37 Hen. 8. c. 17. Sect. 4.

DODDER, Cufcuia and Epitbymum, in medicine, is an atte- nuant and aperient ; and as fuch prefcribed in obftrudtions of the vifcera, in dropfies, jaundies, and other chronic dif- eafes. See Cuscuta and Epithymum.

DODECACTIS, in natural hiftory, a name by which Linkius, and fome other authors, have called a kind of aftrophyte, or branched ftar-fifh, which has twelve rays, firft parting from the body, and each of thefe finally divided into many others.

DODECADACTYLON, in anatomy, a name given by fome of the old authors, to the gut called the duodenum, from its be- ing ufually about twelve fingers breadth long. It is the firft part of the fmall guts, beginning from the pylo- rus of the ftomach, and ending where the gut jejunum begins : it is fo called, as if it were the length of twelve fingers, which yet is never obferved in any men amongft us; perhaps the antients miftook, from inspecting the guts of fome brutes. It is molt ufually called Duodenum. Blancard.

DODECANDRIA, in Botany, a clafs of plants which have hermaphrodite flowers, with twelve ftamina or male parts in each. See Tab. r. of Botany, Clafs 1. The word is formed of the Greek JWefta twelve, and ev«? male. Of this clafs of plants are the afarabacca, agri- mony, &c.

DODO, in zoology, the name of a bird, called alfo by fome cygnus cucullatus, by others gallus gallinaceus pcrigrinus, and by Bontius drcnte. It is a very lingular bird, fomewhat larger than a fwan, but wholly different from the fwan in fhape, though by fome efteemed a kind of that bird. Its head is large, and is covered with a membrane refembling a hood ; its beak is of an oblong figure, and is yellow at its origin and black at the point, and is fomewhat crooked : it is very naked, having only a kw feathers fcattered over its body, and the rudiments of wings made up of a few naked quills ; the hin- der part of its body is very bulky and fat, and has a tail made of four or five curled greyifh feathers, refembling thofe of the oftrich. Its legs very thick and ftrong. See Tab. of Birds, N° 22. Ray's Oniithol. p. 107.

DODON^EA, in botany, the name of a genus of plants about which authors were very unladed in their opinions, till Lin- nasus characterized it under this name. Burman has made it a fpecies of the carpinus, and Plumier of the ftapbylodendron. The characters are thefe: The perianthium is divided into three oval, erect, and equal (egments. There are no petals. The ftamina are eight in number, and are extremely fhort. The anthers are ot an oblong figure, they fraud very low,

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