Page:Cyclopaedia, Chambers - Supplement, Volume 1.djvu/600

 D I A

D I A

Cornijh Diamonds, in natural hiftory, a name given in England to all the fpecies of cryftals, which are computed of a column, terminated at each end by a pyramid. The name takes in two genera of cry Aral, of each of which there are feveral fpecies. Dr. Hill lias determined this to be the true figure of per faSt cryftal, and accounts all thofe which are af- fixed by one end to fome folid body, and terminated at the other by a pyramid, to be mutilated or imperfect cryftals. The fame author, according to the length or thicknefs of the intermediate column, has divided thefe bodies into two genera, the fir ft the mac rote lofty la, the other the brachyteloftyla. Hill's hift. of fof. p. 160 to 165. See the articles Macro- telostyla and Brachytelostyla. Diamond Powder is of great ufe for grinding hard fubftances. And Mr. Boyle obferves, that though it be much dearer than emery, yet it makes fo great difpatch, and the tools employed laft fo much longer, as greatly to over-balance the cheapnefs of the emery. Boyle, Phil. Works abr. vol. r. p. 135. DIAN^E Arbor. — - Lewenhoeck, in one of his papers of the Phi- lofophical Tranfactions, defcribes a microfcop'ic kind of Arbor Diana ; which muft afford the curious in thofe obfer- vations, a very pleafmg fpectacle. Having diflblved fome pure filver in aqua fortis, and weakened this lolution, by adding fome common water to it ; after this, putting this diluted fo- lution into a glafs, and dropping into it a few filings of copper, one particle at a time ; there will be found on fome of thefe, ex- tempore filver trees; the filver leaving the liquor,and affixing it- felf in very ("mall particles to the copper, which, as they grow more and more numerous, link themlelves to one another, and form the fame ramofe mafles that are called the filver trees. A Item, or main trunk, is, in this cafefirft form'd, and after this a number of fine and elegant branches growing from it every way, till at laft there is a whole tree refembling thofe low and headed oaks, which are common on heaths and in other barren places. This is fo fudden an effect of" the putting to the copper, that a few feconds are fufficient to form feveral trees. If a few more particles of copper are thrown into this liquor, the whole quantity of filver that was held in a ftate of folution in it will be precipitated from it, and fixed in the form of thefe fmall trees and fhrubs on the feveral pieces of copper. The formation and arrangement of thefe fmall parti- cles of filver into trees, is not more natural in this ftate of their feparation from the particles of a fluid, in which they were fufpended, than in their natural concretions within the bowels of the earth, where they fix themlelves to the furfaces, and within the cracks and crevices of hard ftones, in the fame arborefcent forms ; and the mod common filver ores afford us an infinite number of what may be called natural Arbores Diana,, or trees of native filver. On comparing thefe natural filver trees in the ores, with thofe formed upon the particles of copper, from a water in which they were fufpended in a ftate of folution, it appears, highly probable, that in the time of the origin of thefe ores, the ftone which makes the bed, or matrix, in which the rich metal now lies in branches and flakes, was foft and fluid ; and that, at that time, the particles of filver were as clofely combined among, and as per- fectly fufpended in its matter as thofe of the folution in this experiment are in the liquor; and that when the matter of the ftone came to coalefce, and harden its particles, uniting toge- ther, formed hard concretions ; from which the fluid was ex- cluded, or driven out, and with it the filver ftill fufpended in it : hut, as this fluid, fa much altered, by the feparation of the ftony matter from it, was now no longer equal to the office of holding the filver fufpended in folution, it became jutt like this diluted folution of filver in the acid, ready to part with, and depofite it in the form of trees and fhrubs, on any fub- ftance proper to receive it; and that the ftony particles, now feparated, and coagulated into hard mafles, were fuch proper fubftances ; and did exactly, in this natural precipitation, what the filings of copper do in the artificial one. There is yet the more analogy in this cafe, becaufe, both the filver and the copper added afterwards, are fubftances foluble in the fame menftruum that is employed ; and fo it appears evident, that the ftony matter of the matrix, or bed of the filver ore, and the filver itfelf were both equally foluble in that menftruum, whatever it was, which before held them both fufpended : and that as foon as the one of thefe two foluble fubftances was added to the liquor in its folid ftate, the other was precipitated upon it in this branched form. Philof. Tranf. N^ 286. p. 1496. See Arbor Diana, Cyd. DIANDRIA, in botany, a clafs of plants, which have herma- phrodite flowers, with two ftamina or male parts in each. The word is formed of the Greek A/s twice, and Av«p male Of this clafs of plants are the jeiTa mine, philierea, olive, rofe- mary, &c. See Tab. 1. of botany, Clafs 1. DIAPASON (Cyd.) — The antients had {even variations, fchemes, figures, or (pedes of the Diapafon, arifing from the various pofitions of the tones and femi -tones in the fcale. The firft fpecies of the Diapafon was from the hypate hypaton to the paramefe ; or from B fy to b £ of our notation. It was called Myxolydian.

The fecond, called Lydian, from the parypate hypaton, to the
 * rite diezeugmenon, or from C to c.

The third, called Phrygian, from the Lichanos Hypaton to

the Paranete Diezeugmenon ; or from D to d.

The fourth, called Dorian, from the Hypate rnefon to the

Nete Diezeugmenon ; or from E to e.

The fifth, named Hypolydian, from the parypate rnefon to the

trite Hyperbolaron ; or from F to f.

The fixth, called Hypophrygian, from the lichanos rnefon to

the paranate Hyperbolason ; or from G to g.

The feventh, named Hypodorian, Common and Locrian, from

the mefe to the nete Hyperbolason, or from the Proflambanome-

nos to the mefe, that is, from our a to a a, or from A to a.

Eudid. Introd. Harm. p. I5,feq, Bacchus, p. 18. Edit. Mei-

bom. See Diagram.

Diapason Diatejfarcn. The Pythagoreans did not admit this interval as a confonance or concord ; for this reafon, that its ratio 8 : 3 was neither multiple nor fuper-particular. But Ptolemy contends for its being a good concord for this reafon, that the Diapafon added to any concord, produces a concord. Ariftoxenus herein agrees with him. Vid. fPaM/s Append, ad Ptolem. Harm. p. 155.

DIAPERD, in Heraldry, feeDiAPRE, Cyd.

DIAPHRAGM (Cyr/.)— The Diaphragm is looked upon as a double digaftrick mufcie, made up of two different portions, one large and fuperior, the other fmall and inferior; the firft is called the great mufcie of the Diaphragm; the fecond, the fmall one.

The great or principal mufcie is flefliy in its circumference, and tendinous or aponeurotic in the middle. This centre is of confiderable breadth, and reprefents in fome degree a trefoil leaf. The flefhy circumference is radiated, the fibres of which it is compofed being fixed by one extremity to the edge of the middle aponeurofis, and by the other to all the bafis of the ca- vity of the thorax, being inferred by digitations in the lower parts of the appendix to the fternum, of the Weft true rib?, of all the falfe ribs, and in the neighbouring vertebrae. There are therefore twelve coftal infertions, two vertebral, and one fternal. The fibres inferted in the appendix enfiformis run from behind dire&ly forward, and from a fmall parallel plane ; The firft coftal infertion runs a little obliquely toward the car- tilage of the feventh true rib ; the fecond is into the whole car- tilage of the firft falfe rib ; the third partly in the bone, and partly in the cartilage of the fecond falfe rib ; the fourth in the bone, and fometimes a little in the cartilage of the third falfe rib; the fifth in the bone, and a little in the cartilage of the fourth falfe rib, being broader than the reft ; the fixth is in the cartilage of the laft falfe rib, and alrooft through the whole length of the bone. At the head of this rib it joins the verte- bral infertion, which runs from the lateral part of the laft ver- tebra of the back to the firft vertebra of the loins. The late- ral infertions of the great mufcie of the Diaphragm on the right fide appear to be lower than thofe on the left, and the right lateral portion appears to be larger than the left, as being more arched. The fmall mufcie of the Diaphragm is thicker than the other, but of much lefs extent; it is fituatcd along the forelide of the bodies of" the laft vertebra of the back and feveral of thofe of the loins, being turned a little to the left hand ; it is of an oblong form, reprefenting in fome meafure a flefliy collar, the two lateral portions of which crofs each other, and afterwards become tendinous towards the lower part. The upper part of the body of this mufcie is fixed in the Hope of the middle aponeurofis of the great mufcie. The outer edges of the ala?, or lateral portions, join the pofterior plane of the great mufcie, and adhere to the body of the laft vertebra of the back. The extremities, called alfo pillars or crura, are inferted by feveral tendinous digitations in the ver- tebras of the loins ; the upper part of the flefhy body is formed by a particular intertexture of fibres belonging to the abe ; the fibres that come from the left, crofs over thofe from the right ; and this again fends a fmall fafciculus of fibres over thofe of the left. The right crofs is larger and longer, the left fmaller and fhorter. An oval opening in this mufcie gives paftage to the cefophagus, and the aorta lies in the interftice between the two crura. There are in all three openings in the Diaphragm, one round and tendinous for the paffage of the vena cava ; one oval and flefhy for the extremity of the cefophagus; and one forked, partly flefhy and partly tendinous, for the aorta. WinjlovJs anatomy, p. 226.

The Diaphragm is the chief organ of refpiration. Dr. Mar- tin thinks the enlargement of the cavity of the breaft in infpi- ration more owing to the depreffion of the Diaphragm, than to any remarkable change in the pofture of the fternum and ribs. See Respiration.

Mr. Senac has given us a new defcription of the ftru&ure of the Diaphragm, with remarks on the action of this mufcie. See Mem, Acad. Scienc. 1729.

DIAPORESIS, AmT.ipHOTf, in rhetoric, is ufed to exprefs the hefitation or uncertainty of the fpeaker. We "nave an example in Homer, where UlyfTes going to re- late his fufferings to Alcinous, begins thus :

^uiifrimum, quid delude, quid poftrem ebauar ?

This