Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/285

 POR

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ricardium, and has two ventricles ; and this part, as well as the lungs, agree in all refpedts with thofe of quadrupeds. The fifh. having no neck, the larynx is confequently very fliort. The pipe in the head, thro' which thefe fort of fifties draw in their breath, and fpout cutwater, lies before the brain ; it terminates outwardly in one hole, but it is within divided in- to two parts by a bony feptum, fo as to reprefent two nof- trils ; but at its lower end it again becomes one hole, and opens into the mouth by a common orifice furnifhed with a Very ftrong fphincler mufcle, by means of which it may be fhut and opened at pleafure. Above this fphindter, the fides of the pipe are lined with a g!andulous flefti ; from which when pre/Ted, a glutinous liquor is forced out of certain little holes in it into the infide of the pipe : above the noftrils is a ftrong valve or membrane, which ferves to ftop the pipe at pleafure, and prevent any water from getting into it, but when the fifh requires it within. The fiftula are fix blind holes, having no outlet, four tending toward the fnout, and two placed above the valve, which flops the noftrils, and two beneath it ; and two tending toward the brain, having a long and narrow ca- vity which feems intended for the ufe of fmelling, tho', on opening the brain, no fuch olfactory nerves or procefTus ma- millaris, as other animals are furnifhed with for this purpofe, are to be found. The eyes are fmall, and the fnout is verv long, and furnifhed with ftrong mufcles ; the ufe of thefe is to enable it to root up the fand and dirt at the bottom of the fea, and feed on the fand-eels and other creatures it finds bu- ried in it. The brain is large, and refembles that of man, and probably it has been an obfervation of this that has given occafion to the opinion of this animal having fo great a fhare of will and understanding, and has given rife to the ftory of Herodotus, that Arion was carried to fhore on the back of one ; and that of Pliny the elder, of one of thefe fifh fo fond of a certain boy, that he ufed to carry him daily from Baize to Puteoli, acrofs the fea to fchool, and wait to carry him back again at a certain time. Pliny the younger gives us alfo a ilory of this kind in bis epiftlcs.

The teeth of the porpefs are in each jaw forty-eight in. num- ber; they are fhort and blunt, and refemble fo many pegs. The antients, particularly A riftotle, have faid that the tongue of the porpefs or dolphin is tied down fall to the lower jaw, all along the middle. Rondeletius has difputed and contra- dicted this obfervation ; but Mr. Ray proves it to be true, and that the modern author is in an error. Ariflotle denies this fifh ear-holes, and experience fhews that he is in the right ; nor has it any noftrils, except thofe within the fiftula. The breaft bone is remarkably fmall. The name porpefs is given it becaufe of its refembling a hog ; which it does in the fnout, the fat, the vifcera, and many other particulars. Phil, Tranf. N° 74. PORPHYRIO, in zoology, the name of a bird figured and de- scribed by all the natural hiftorians from one another, but which, it feems, none of them ever faw ; and there is fome room to doubt whether there be in nature any fuch bird. Ac- cording to the accounts we have of it, it appears to be of the gallinula or moor-hen kind, and is all over of a fine deep blue, only the middle of the tail is at the extremity of a grcyiOi white, its legs and feet are of a fine fhining purple. There have been fome fabulous things related of it, as its hav- ing five toes on each foot, and the like ; but if there be any fuch creature, it feems to be a moorhen of thefe remarkable colours. Gefner de Avib. Ray's Ornithol. p. 238. Porphyiuo Americanus, in zoology, a name by which fome have called the quach'dto, a very beautiful fpecies of Brafilian moor-hen. See the article Quachjlto, PORPHYRY, (Ccyl.) porphyria, in natural hiftory, the name of a genus of foffils generally, but improperly, added to the marbles, and called by us porphyry. They are flones of a plain uniform mafs, fpotted or veined, with feparate concretions of great hardnefs, giving fire with fteel, not fermenting with acids, and very flowly and difficultly calcining in a ftrong fire. Hill's. Hift. of FofT. p. 494.

Of this genus there are only three known fpecies : 1. The purple kind, commonly known by the name of porphyry, among the workmen. 2. The hard red-lead-coloured kind, variegated with black, white, and green. And 3. The very hard flefh-coloured one, variegated with white, green, and black. The purple porphyry is a fubftance which has been well known, and highly efteemed in all ages of the world. It has its name from the Greek wofftifo?, purple, as that re- markable colour always afforded a very obvious diftinction for it, from the other kinds. It is of an extreme firm and compact ftruclure, remarkably heavy, and of a fine ftrong purple, variegated more or lefs with pale red, and white, and with a fmall number of little, and generally difregarded black flaky fpecks. Its purple is of all degrees, from the deep tinge of the violet to a pure claret colour; and its variegations are ufually difpofed in fmall fpots, ufually fmall and difunited, but fometimes running into one another, and making large blotches. It is very difficultly cut, becaufe of its very great hardnefs ; but is capable of a very fine polifh. It is found in great quantities in Egypt ; and we find was had thence alfo in very early times. It ferves us for flones for the apotheca- ries and colourmen, to grind or levigate their powders on,

and on any other occafion where great hardnefs is required The red-coloured porphyry is alfo an extremely beautiful and valuable fubftance, but is hitherto unknown among our lapida- ries. It has the hardnefs, and all the other characters^ thepurple phorphiry, and greatly exceeds it in the variety of its colours. Its ground is exactly of the bright fine red of our minium or red lead, but is fomewhat deeper or paler in the different parts of the mafs : this is beautifully veined with green, in broad and regular lines ; there are alfo fome confidently narrow, and among thefe feveral perfectly white flreaks, and a mul- titude of fmall black fpecks. It is of extreme hardnefs, and capable of a polifh equal to that of the femi-pellucid gems. It is found in great plenty in the ifiand of Minorca, but has never yet been regarded as a ftone worth importing into Eng- land.

' The fejh-celoured porphyry. This is another very little known, but extremely beautiful ftone : it is of an irregular, but very compact and firm texture, and of a pale flefh colour, often approaching to white, and variegated with black, green, and white in large blotches, from half an inch to an inch broad ; and fometimes, tho* very feldom, difpofed in regular veins. It appears very livid and glofTy where freih broken, and is ca- pable of an extremely elegant polifh ; and is fo very tranfpa- rent, efpecially in its green parts, that when polifhed one may fee deep into its fubftance. It is found in immenfe ftrata, in Arabia Petraea, and in upper Egypt, and in detached nodules is common to almoft all parts of the world : Germany abounds with them; and we have of them in many parts of England and Ireland. They are found in many places on our fhores, and in fome parts of Devonfhire far from the fea. Hill's Hift. of Foil' p. 494 to 498.

Mr. Boyle tells us, that he caufed porphyry to be cut by means of emery, fteel faws, and water. He obferves, that in his time, the workmen in England were ignorant of the manner of working upon porphyry, and that none of them would undertake to cut or polifh it. See Works abr. Vol. I. p. lit.

Porphyry-^//, in natural hiftory, a name given by authors to a fpecies of fea-fhell of the purpura kind, with a fliort cla- vicle and beak. See Purpura.

PORPITES, the hair button -Jione, in natural hiftory, a name given by authors to a fmall fpecies of foffile coral ; which is ufually of a rounded figure confiderably flatted, and ftriated from the center every way to the circumference. Thefe are of different fizes, and of different colours, as greyifli, whi- tifh, brownifh, or bluifti, and are ufually found immerfed in ftone. See Tab. of FofT Clafs 7. and Hill's Hift. of Fori p. 641.

PORRUM, the leek> in botany, the name of a genus of plants, the characters of which are thefe : The flower is of the lilfia- ceous kind, being compofed of fix petals, and of a bell-like fhape. The piftil which ftands in the middle of this flower, finally becomes a roundifh fruit divided into three cells, and containing roundifh feeds. To this it may be added, that the ftamina are broad, and are terminated by three filaments, the middle one having an apex. The flowers alfo are ufually col- lected into round heads, and the roots are long, cylindric, and tunicated, the feveral crufts often running up into flat or hollowed leaves.

The fpecies of hek, enumerated by Mr. Tournefort, are thefe: r. The common headed hift. 2 The leek with variegated Ifl&vcs, elegantly ftreaked like thofe of the painted grafs. 3. The broad-leaved fectile leek, 4. T'he wild vineyard leek. 5. The double-headed wild leek. And 6. The vitigineous wild leek of Gerrard. 7ew».Inft. p. 382.

PORT (Cyd.) — PoRT-la/l, in a fhip, the fame as the gun- wale ; therefore they fay a yard is down a port-lajf, when it lies down on the deck.

PoRT-ro&fij", in a fhip. See Ropes.

PORTABLE laboratory. See Laboratory.

PORTE- c/nVr, in the manege. See Stirrup.

PORTEGLO, in the glafs trade, the inftrument with which the founder, or conciator, fcums the glafs while melting. Ne- ri's Art of Glafs, p. 241.

PORTER (CycL)— Porter, in the manege, fignifies to di- rect or pufh on a horfe at pleafure ; whether forewards or up- on turns, &c.

PORTERAGE, a kind of duty paid at the cuftom- houfe, to thofe who attend the water fide, and belong to the package- office. Thefe porters have tables fet up, afcertaining their dues for landing of ftranger's goods, and for fhipping out the fame. Merch. Diet

PORTISCULUS, among the Romans, an officer who had the direction of the rowers in a galley. He was otherwife called paufarius and hortator remigum. Pit'tfc. Lex. Ant. in voc. See Pausarius and Hortator.

PORTIUS pifchi in zoology, a name given by fome to a fifh called by others the mugHater, or black mullet. It is a very fcarce fifh, much refembling the common mullet in fliape, but all over of a fine black, and having feveral lines of a. deeper black than the reft, running longitudinally from the gills to the tail. It has a very wide mouth, and has feven or eight prickles on the back, feparate from one another, and joined into a fin by a membrane in the ufual way ; thefe are placed immediately before the back fin. JVilhghby'% Hift. Pifc. p.276.

POR-