Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/274

 POL

POL

Pcllard, in zoology, a local name for the young Cliu fmall fifh of the cofe-fifh, or rawling-pollack kind. It is ufed in Cornwall, &c. Willugbby's Hiit. Pifc. p. 169. POLLEN thurify in the materia medica, a term ufed hy the Latin writers, to exprefs the manna thuris, or manna Idanotts, of the Greeks, but that very improperly; for the word fatten thuris properly fignifies the frankincenfc reduced to a powder, but this was not what the antient Greeks called marina thuris, but the fmall fragments which were broken off from the large pieces, in the gathering or packing up.

The manna ufed in medicine by the Greeks and Arabians was not formed into large flakes, as ours is ; but was com- pofed of fmall fragments or grains, and therefore they called by the fame name the fmall granular or fragments alfo of other things : it was thus that the broken frankincenfe was called manna thuris,

Thecuftom of the times of favingall the fragments of this drug, made them collect even what was in fo fmall pieces as to refemble powder ; but tin's, tho' mixed with the reft, was not properly the manna thuris. This gave occafion to the adulterating this commodity, and Diofcorides tells us, that even in his time they had learned the trick of putting the powder of the rcfin of the pine tree among it ; and this grow- ing worfe and worfe, they at laftdifcarded it, and would pur chafe only the fragments without the powder. Thefe frag- ments they called thus minutum, to diftinguifh them from what was then called manna thuris, tho' improperly, and which was the adulterated mafs of refin and fragments of ohbanum. POLLICIPES, the toe-jhell, in natural hiftory, the name of a genus of fhelis, the characters of which are thefe: they are multivalve flat fhelis, of a triangular figure, each being com- pofed of feveral laminae, which end in a (harp point. They Hand upon pedicles, and are furnifhed with a great number of hairs. We have only one known fpecies of this genus, and this always found in large duffers See Tab. of Shells, N° 27. POLLINCTORES, among the antients, an appellation given

to thofe who warned and anointed the dead. Pitifc. "in voc. POLLINCTURA, a word ufed by fome authors to exprefs the

embalming dead bodies. POLLING, in gardening, the operation of difperfing the worm- cafts all over the walks, with long afh-poles : this, befides de- stroying worm- caffs, is very beneficial to the grafs of the walks. See Grass-wa/at. POLLUCTUM, among the Romans, a feaft kept in honour of Jupiter Dapalis, Hercules, £sfc at which facrifices were offered to the Gods. Pitifc. in voc. POLLUTION (Cycl.)— Pollutio nofiuma, in medicine, the name of a difeafe, which confifts in an involuntary emif- fion of the feed in the night, in time of fleep. This, in different perfons, is very different in degree; fome being affected with it only once in a week, a fortnight, three weeks, or even a month, and others being fubject to it almoft every night.

The perfons moft fubject: to this, are young men of a fanguine- ous temperament, and who feed high, and lead a fedentary life. When this happens to a perfon but once in a fortnight, or a month, it is of no great confcqucnce; but when it hap- pens almoft every night, it greatly injures the health; the pa- tients look pale and fickly. In fome the eyes become weak and inflamed ; fometimes they are affected with violent de- fluxions, and ufually, at laff, are circled round with a livid appearance of the fkin.

This diftemper is to be cured rather by a change of life than by medicines. When it has taken its rife from high diet and a fedentary life, a coarfer food, and the ufc of exercife, will generally cure it; but if any medicines are to be given, nitre . alone will do more than almoft all the reft. This may be taken in large dofes, a fcruple at a time, with very little li- quid with it, and muft be continued for fome time at night going to reft. The root of the water-lilly is greatly recom- mended by fome in this cafe ; and by others, the feeds of the agnus caftus ; but it is very doubtful, whether they have either of them any effect.

■Perfons fubject to tins difeafe muft never take any ftimulating purges, 2nd muft avoid, as much as poffible, all violent paffions of the mind : and tho' exercife is recommended in moderation, yet if this be too violent, it will rather increafe the diforder than do any thing towards its cure. Junck's Confp. Med. p. 486. POLPHOS, a word ufed by fome authors to exprefs a bulb or

bulbous root. POLPOCH, in zoology, a fpecies of ferpent faid to be found in Jucatan, a country bordering upon New Spain. It can bite with the mouth and fling with the tail. H r >ffm. Lex. univ. in voc. POLVERINE, the calcined afhes of a plant; a fubftancc of the nature of our pot-afhes. or pearl-afhes. It is brought from the Levant and Syria; but In the glafs trade, tho' it be of the nature of the other afhes they ufe, it is always to be preferred to any other. The barillia, or pot afhes of Spain, yield more pure fait than the polverine of the Levant, but the glafs made with it has always fome tinge of bluiflinefs : that made with the polverine is ever perfectly

white, and this is the fubftance that ought always to be ufed for the fincft cryffal.

The method of procuring the pure fait from thefe afhes, is to fift them and throw them in a proper quantity into a large copper of boiling water, continuing the boiling till all the fait of the afhes be dillblved by the water, and adding to the water, before the polverine is put in, about ten pound of tar- tar calcined to a blacknefs. The lee or water thus impreg- nated with the fait, muft ftand a confiderable time to fettle ; and when perfectly clear, muft be evaporated till it thicken, and begin to fhew a white dry fait about its edges : then the fire mult be kept very flow, and a fkimmer full of holes being funk in to the bottom of the copper, the fait will gather and harden upon it; and this muft be taken out every now and then, and the fait taken off and dried for ufe. Three hundred pound of polverine thus yield eighty or ninety pound of clear fait. When this is dried, it muft be flightly calcined in the glafs furnace, and then powdered and fitted through a coarfe fieve, and kept dry. Neri's Art of Glafs, p. 2. POLYADELPHIA, in botany, a clafs of plants, whofe ftamina are formed into three or more feparate bodies. The word is formed of the Greek ■rot.-Jc, many, and «$&$<£. communities. Among the plants of this clafs are orange- trees, St. John's wort, &c. POLYANDR1A, in botany, a clafs of plants with hermaphro- dite flowers, and a large number of ftamina, or male parts, in each. See Tab. 1. of Botany.

The word is derived from the Greek m7M& many, and «nw>, male. The hermaphrodite flowers of this clafs have a large number of ftamina on each, always more than twelve, and thofe growing to the receptacle of the future feeds. Of this clafs are the water-lilly, poppy, celandine, &c. POLYANTHEMUM, in botany, a name given by fome au- thors to the water-crowfoot, from its great number of flowers. Ger. Emac. Ind. 2. POLYCEPHALON, H.»%, many, and KepSas, a joint; and as it is ufually applicable to this, and all the other jointed plants, it is ufed by fome for the name of the feveral fpecies of equifetum, or horfetail, as the word polygo- num is.

Neophytus defcribes one fpecies of this, which he fays is called orecn, from its growing in mountainous places. This, he fays, looks like a young reed, and has feveral joints in the main ftalk, which are received into one another as fo many cups or boxes. He adds, that the leaves are like thofe of the pine-tree: what he calls the leaves, are probably the tender branches; and then this defcription will agree very well with our great marfh horfetail, which grows in wet places in moun- tainous countries, and about the fprings in our hills. This is the horfetail to which the greateft virtues are attributed by this author ; but the whole account of the hippuris, polygonum, and equifetum, is fo confufed, that there is little to be learnt from what the antients fay of them, without repeating the trials j of their virtues.

POLYCROTA, in the naval architecture of the antients, a word ufed to exprefs fuch of their gallies as bad three, four, five, or more tires of rowers, fcatcd at different heights ; they were diftinguifhed by this term from the monocrsta, or thofe which had on : y Angle rows of oars.

The number of rows of rowers in the po'ycrote gallies has gi- ven occafion to fome to fuppofe thofe veflels of fuch a height from the water as is fcarce credible; we have, however, 'no warrant for this, but the commentators have given occafion to the opinion, from their not having been able to frow the rowers in lefs room, and have meafured the height of the veflel by their own (kill in this fort of architecture, not by that of the people who built them. Meibom has found a way to take off a great deal from the imaginary height of thefe gallies. He has two inventions to anfwer this purpofe : by the firft of them, he {hews how the lateral rowers may be fo placed, that he who fits behind another may move his hands and oar under the feat of the rower who fits next before him ; by which means three lateral rowers, which, according to Scaliger's way of reckoning, would require thirteen feet and an half, will be placed in the heighth of feven feet and an half. By the fecond invention, he finds out a place in the veflel for almoft half the number of rowers ; forafmuch as on the fides of the aforefaid rowers, he places others in the middle of the fhip, upon tranftra or tranfverfe feats, which he imagines thruft out their oars under the feats of the lateral rowers; by this contrivance he has gained no lefs than nine feet in the heighth of a quinqueremis.

t he different feiies of rowers were called by different names 5 the thalamitee were thofe who fat in the loweft row ; the z\- gites were thofe who fat in the tranftra, or crofs feats; and the thramta thofe who fat uppermoft of all in the veflel. The molt furprizing account of a polycrote veflel among the 2 antients.,