PYR

347

PYR

I

PU:

*Z0l;

ana.

0 p The surface of this substance is rough, uneven,f^e s ; a kaked appearance. It comes to us in pieces, fromJlter n£ ^ a nut t0 t* iat °f an egg. It is wholly destitute off ra 'tstre and transparency. It is easily frangible, and' v jth Ur . e 's uneven or earthy, and porous; commonly filled'tty P‘des 0 f putnice, quartz, scoriae, &c. Hardness, 3.

bin Specific gravity from 2.570, which is that of

j'^aaibl - t0 rare iy 2.8. Its smell is earthy. It is not

3o s it s e 111 cold-water; but in boiling-water it graduallya ^ ne earth. It does not effervesce with acids.assum es a darker colour, and easily melts intov is a S> or ! with borax, into a yellowish-green glass. Beforeeate< I> it is magnetic, hut not afterwards.

%

ts magnetic,analysis, it contains

By Mr.from 55 to 60 per cent, of

e°Us eai 'th, 19 to 20 of argillaceous earth, 5 or 6 of cal-

earth,

When mixed with

( and from 15 to 20 of iron. _ _

Proportion of lime, it quickly hardens; and this indu-^° ee eds 68 P^ ace even under water. This singular property■ >ron ’- aS - Ki*’ wan supposes, from the magnetic state of1 v div'a 1 Contains ; f° r this iron, being unoxygenated, sub-°%in„ l e( i> an< I dispersed through the whole mass, and thusHid, ^ a large surface, quickly decomposes the water withls m 'xed, when made into mortar, and forms a hardp lab ,anal °g° ua t0 sp ecu l ar iron-ore, as it does in theIt. | n _ which water is decomposed, in the experimentsN in e aVo ' 8 ' ei ’ an< l Dr. Priestley; for in these the iron swells' ll o m 0r f aSes ' n bulk; and so does puzzolana, when formedI'Pal n Se ;u '> as we learn from Higgins on Cements . One prin-'?1| it li® 6 seems to be to heat tlie water, as, while it is

?'ai

K,

°annot

Oit s ' M '( uc pervade the caked argil that invests the ferru-an<l ‘ ltlc les; yet, in time, even cold water may pervadek SerVe d l^ UCe lar< l ness > an< l bence, as M. Dolomieu hasp be l 0 ^J lVas become harder when moistened. If the mor-^air x °. ex P°sed to the atmosphere, fixed air, as well aswni Unite t0 the iron, rust will be produced, and thej, *?, o Ver not then harden, as Dr. Higgins has noticed,tl'i^lana' ', V ' I ‘ < ^ 1 l ava bas flowed, is frequently converted intoa a re ’ out volcanic scori* never afford it; either becausep^Hts ^, Uc ^ calcined, or retain sulphur, or its acid. TheEij°P e fti es . ere well acquainted with this substance and itsts* 0 ’a j n< ^’ among them, its principal use, as it has beenbleats f ern times, ‘

;.° r buildings s

was that of mixing it with theirsunk into the sea. As it hardens and

'.''tlier l . ter » b >s of particular service in making moles,' n mal 'iii me places.

iij -i and ^1 TLE, (from ttvkvovuXoj, formed from tukvos;,

flj® Mi er 9 ^ °s> co ^ urnn ,) in the ancient architecture, a build-

iii? tl1e h;r , columns stand very close to each other; one'•err • and „ i._i^ „ J . . -. . o .

.‘o*,

a ®. ( l a half of the column being allowed for the

111

is the smallest of all the intercolumniationsdistil Vitruvius - Some make it the same with systyle ;'a tlJ'?, U ' s j l *1*8 latter by its allowing half a module'Vr PVe ^ 0l l nt bian intercolumniation.

°a ) pos' OSt ^ e ’ ^ r ‘ Eve] Y n observes, chiefly belonged to^l? 1 ^aild' Ue 0l ' der > and was used before the most magni-\| 0r ae, C( | n ». 3 ■ / ls , at present, in the peristyle of St. Peter’s)’et r ns,s ! in g of nearly three hundred columns; and°f Ki 6lna ' n °f the ancients among the lately-discovered

bq 8 j 14 8oi i( j U ’ (b'om the Greek, nvpayis —derived from irvp,V^ 1 . and te on a square, triangular, or polygonal

8 »«?'**** at to P ' n a P°' nt ’ 01 a body whose

.‘ 1 rectilinear figure, and whose sides are plain' several verticals meeting together in one

a solid figure, consisting of several

triangles, whose bases are all in the same plane, and haveone common vertex.

The pyramid is said to be triangular, quadrangularquinquangular, &c., according as the base is triangular,quadrangular, &c., The pyramid may be called a square,triangular, &c. cone; or the cone may be denominated around pyramid. When very narrow at bottom, i. e. tlieiibase very small, they are called obelisks and needles.

Some derive the word from nvpoc, wheat, and agaw,colligo; pretending that the first pyramids were built by thepatriarch Joseph, for granaries. But Villalpandus andBryant, with much better reason, derive the word from irvp,fire ; because of their ending in a point like flame; whencethe latter writer conceives them to have been originallyaltars dedicated to the sun.

Wilkins, conversant with the Coptic tongue, suggestsanother derivation from that language, in which pouro signi-fies a king, and miri, a race or generation ; and he says, thepyramids were thus called, because they were erected topreserve the memories of the Egyptian kings and theirfamilies; and that those who descended from them hadrecourse to these pillars in order to prove their pedigree :but this supposition can have very little weight, when it isrecollected,that the memory of tlie founder of the largest ofthe Egyptian pyramids was lost long before the daysof Herodotus . And as to their having been erected forgranaries, their internal capacity is so limited, that the nationcould have derived no just benefit from them. We thereforeprefer the idea of Villalpandus and Bryant as to the deriva-tion of the term.

Pyramids are now, sometimes, erected to preserve thememory of singular events, or to transmit to posterity theglory and magnificence of princes; but, as they are the sym-bols of immortality, they are more commonly used as funeralmonuments. Such is that of Cestius at Rome, the mausoleum of that distinguished Roman, who was one of the seven officerscalled Epulones, and is said to have lived under Augustus :it was repaired in 1673 by Pope Alexander VII .

The pyramids of Egypt , comprehending the great andsmall, are very numerous ; of these there are about twentyof the largest size. The most remarkable are the threepyramids of Memphis , or, as they are now called, of Glieisa,Geeza, or Gize. The dimensions of the greatest of thesehave been differently stated both by ancient and modernwriters. Herodotus (lib. ii.) makes the base of it to be 800Grecian feet long; Diodorus (lib. i.) 700 ; Strabo (lib. xvii.)less than 600; and Pliny (lib. xxvi. c. 12.) 883 feet. Amongthe moderns, Sandys found it to be 300 paces ; Bellonius, 324;Greaves, 693 English feet ; Le Bruyn, 704 French feet, or750 English feet; Prosper Alpinus, 750 French feet ;Thevenot, 682 ; Niebuhr, 710; Chazelles, 704.80 English feet. In order to reconcile these differences, Dr. Shawobserves, that none of the sides of this pyramid are exactlyupon a level; so that it is difficult to find a true horizontalbase ; besides, it is impossible to say how much the drifts ofsand, to which it is exposed, may have been accumulatedabove the foundation of it; and, therefore, all calculationsdepending upon the time and circumstances of the situation,when they were made, must be exceedingly precarious. Theperpendicular altitude of it, according to Greaves, is 499 feet;but its oblique height is equal to the breadth of the base,or 693 feet. The whole area of the base contains 480,249square feet, or 11 rVWff Knglish acres. The height, accord-ing to Herodotus, is 800 French feet; according to Strabo ,625; according to Diodorus Siculus , 600 and a fraction ; asstated by Le Bruyn, 616; by Prosper Alpinus , 625 ; byThevenot, 520 ; by Niebuhr, 440. The ascent to the top of

i