GRANITE. 



, Sereral of the mountains are, as it were, ftrewed with 



blocks of n-ranite, which, at a diltance, appear as numerous 

 herds of cattle ; and it is this circumilance which is faid to 

 have procured this ridge the naire of _ A(k<n-(holo, a 

 Mon"-ole word, denoting herd-like mountains. All thefe 

 detached rocks are fragments of the vail itrata of granite 

 that compofe the greatell part of the Dauric mountains. 

 The fummits of the Goattield and other mountains of 

 Arran have the appearance of huge walls compofid of large 

 granitic maffes. At Huclgouet, in Lower Brittany, we arc 

 informed bv Monnet, as alfo in the Vofges, enormous maiTio 

 of o-ranite are fcen piled on one another, and forming moll 

 e>ct°aordinarv groups. The granite being here divided 

 into maffes by hlTures, which are filled up iMth granite pof- 

 fefling lefs folidity, this latter is fooner acted upon by at- 

 mofpheric agencv, whence, by its difmtegration, the maffes 

 become perfeftly detaclied, and adopt various pofitions. 

 But befides the accidental groups formed by the rolling 

 down of the rocks, there are other groups of granitic rocks 

 at Huelgouet, that appear to be in their natural poiition, 

 and many of them form an alTemblage of rock mafles, which 

 have a pcrfeClly rhomboidal form, and are regularly joined 

 to each other by means of their correfponding planes. One 

 of the infulated rocks in a group at Huelgouet, is called 

 Pierre branlanle, or the rocking ftone : it is 21 feet long, 

 feven feet high, and eight feet wide, and its cubical content 

 is 1 160 feet: it is fo accurately poifed on the edge of an- 

 other rock, which ferves for its bafe, that the ihvngth of a 

 few men fuffices to change its centre of gravity, and to 

 communicate an ofcillatory motion to it. The phenomenon 

 of the rod'ing Jloiies is not unknown m this country; the 

 largeft is that ieen at the Land's End in Cornwall, where 

 they are called Logan-ltones; it weighs upwards of fixty 

 tons reftiii'^ on another rock of granite of conliderable 

 heiffht dole on the fea-ftiore. " The two ftones," fays 

 Mr Play fair, who avails himfelf of this phenomenon among 

 others to explain the migration of llony maffes, " touch 

 but in a fmall fpot, their furfaccs being confiderably convex 

 towards one another. The uppermotl is fo nearly m an 

 equilibrium, that it can be made to vibrate by the ilrength 

 of a man, thou.^h to overfet it entirely would require a vali 

 force This ariies from the centre of gravity ot the ftone 

 beine fomewhat lower than the centre of curvature of tliat 

 part of it on which it has a tendency to roll ; the conle- 

 fluence of which is, that any motion impreffed on the ftone 

 forces its centre of gravity to rile, (though not very conli- 

 derably,) bv which means it returns whenever the torce 13 

 removed, and vibrates backward and forward, til it is re- 

 duced to reft. Were it required to remove the Konc trom 

 its place, it might be moft ealily done, by cutting off a 

 part or blowing it away by gun-powderj the ftone would 

 then lofe its balance, wonld tumble from its pedcltal, and 

 mi<Tht roll to a conliderable diftance. Now, what art is 

 her°e fuppofed to perform, nature herfelt in time will pro- 

 bablv effecl. If the wafte on one fide of this groat mals 

 (hall 'exceed that on the oppofite in more than a certain pro- 

 portion, and it is not likely that that proportion will be 

 alwavs maintained, the equilibrium of the Logan-ftone will 

 be fubverted, never to return. Thus w: perceive hmv 

 motion may be produced by the combined aAion of^the 

 decompolllion ur.d gravitation of lar-e maffes of rock 



I-^ was probablv from feeing the tantaftical and imitatne 

 forms produced b^- granitic cliffs, and by the dif.ntegration 

 of eranite, that M. Vitte framed his unfortunate hypothelis 

 refpeaing the pyramids of Egypt, and the ruins "* P'--^^^'- 

 poUs, Palmvra, and Balbcc. all which together ylh the 

 temple of .Tupiter at Girg.ntum, the palaces of the Ii.cas m 

 Vol. XVL 



Peru, &c. Sec. were confidered by that antiquary a* produc- 

 tions of nature. 



Granite is much lefs mrtaUifcrous than gncifs and other 

 primitive mountain.' ; but tin and iron abound in it. Be- 

 lides thefe, feveral oth-r metals occur in it in fmall proper- 

 tion, liz. gold, tho-.igh very rarely, in Peru; native filvcr, 

 ahuoft equally feldom, at ^\'ittichen and Alt Wolfach, in 

 tlic Black Eoreft, near veins of filvcr and cobalt; copper; 

 galena, for inllance, at Schreiberlhaufcn, at the foot of the 

 Schncekuppe, in Silefia; bifmuth, zinc, cobalt, manganefe, 

 molybdena, arfeiiic, tungllcin, and wolfram, all ■vhich occur 

 generally in fm.all veins; but tin, galena, and blende, are 

 found ill beds at Zinnwald in Saxony, and in Bjheiaia. 



As to the extent of granite over the world, it may be faid 

 that Icarccly any country we are acquainted with v entirclv 

 deftitute of that rock. In Afia we have the Uralian and 

 Altaic mountains, with the Caucafus; in Africa, the Atlas, 

 feveral mountains of Egypt, thofe of the Cape of Good 

 Hope; in North America, fomc mountains of New York, 

 Penrfylvania, and Virginia; in South America, great part 

 of the Andes, the mountains de los Mariches in the Carracai, 

 the Cordilleras of Pariina, Sierra Nevada de Merida, &c.; 

 in Europe, the Seewoga mountains of Scandinavia, thofe 

 of Finnland, the Carpathes, the Hart?, the Riefcn-gebirge, 

 the mountair.s of Upper Lufatia, a part of the Saxon 

 metalliferous mountari;., (efpecially Eibenllock, Johan- 

 gcorgcntladt, Schwartzenberg, Schneeberg, Ehrenfriederf- 

 dorf, Geier, Naiiendorf, Altenberg, and Zinnwald,) tlie 

 Fichtel-gebirge, the Odcnwald and Schwartzwald, the Alps 

 of Swillerland and S.ivoy, the Apennines, P\renees, tlie 

 mountains of Cornwall, &c. all wlach have granite for their 

 principal conftituent rock. 



The ufe made of granite is n;anifold; it is employed for 

 building, paving, Heps, for troughs in ilaraping mills, for 

 millftones, &c. 



The ufe of granite for architcAural and economical pur- 

 pofes is perhaps no where more amply difplayed than at 

 Petcrfburg, wliere not only the imperial and other palaccji, 

 but even ordinary dwelling houfcs, have their lower parti 

 hned with (labs of granite. The left bank of the great 

 Neva, from the foundery to the gulf of Crouftadt, and 

 both banks of the F<intanka and of the Catharine canal, 

 are lined by high walls conftrucled of fuch (lab.- of granite; 

 as are many bridges over the Neva, balullrades, &c. The 

 pillars, llairs, balconies, S:c. in the palace of Cronrtadt, 

 are almoft all of the fineft kindi of granite. Thofe cm.p!oy» 

 cd for ornamental architecture are cut and polilhed by lapi. 

 daries; but thofe intended for lefs delicate purpofes, fuch 

 as common flabs, fteps, cvhnders, troughs, &c. are worked 

 by peafants, particularly bj thofe of Olonelk. The govern. 

 ment tcwn.o, however, Mofcow not excepted, are too dif- 

 tant from the chief granite mountains, t.; be eni;bkd to 

 make frequent ufe of that rock for tiie above purjofes. 



Granite has been mo:v particularly applied, together 

 with lienite, for the purpofes of arc'iitetture and llatuary. 



by the ancients, e(pccially by t!ie Eg)-ptiaiis ; and many 

 very inteivlling monuments of their Iki'l and 

 Hill exifting in the collections of antiquities. 



patunce arc 



M. Brand has divided the different granites iifed in tLe 

 arts after their predominant colours; the f< I!owi:.g arc the 

 principal Narieties, in which, how.'vtr, the black and while 

 kind is not included, one of its ingredients being horn- 

 blende, which afligns it a place among the fieuitcs. Sec 



SjENlfE. 



6av Gnmu'f of Cl:r£;, in the department of the Rhine ; 



it confilts of white quartz and bLick mica, with large cr\ u 



tals of rofc-colomvd feldfpar. Tlie columns of the Egl;fe 



4 K d Eiice 



