Copy 1, Volume 4

An historical miscellany of the curiosities and rarities in nature and art. Comprising new and entertaining descriptions of the most surprising volcanos, caverns, cataracts, whirlpools, waterfalls, earthquakes, thunder, lightning, and other wonderful and stupendous phenomena of nature.

Date:: [1794-1800]

Credit: An historical miscellany of the curiosities and rarities in nature and art. Comprising new and entertaining descriptions of the most surprising volcanos, caverns, cataracts, whirlpools, waterfalls, earthquakes, thunder, lightning, and other wonderful and stupendous phenomena of nature. Source: Wellcome Collection.

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$ACCOUNT OF THE ROCK-SALT at NORTHWICII, ano THE BRINE-PITS at DROITWICH. ROCK-falt is I'oimd fi'om twenty-eight to forty-i^ight yards be- neath the (urlace of the earth. The firfl ftratuin Or mine met ■with is from fifteen to twenty-one yards iii thickncfs, perfectly folid, and fo liard as to be cut with great difficiilV]^ with iron picks and wedges. Of iate th& workmen Iiave bladed it vvitli giinpOwder, by which they loofen and remove many tons together. The appearance of the fait is extremely refembling that Of brown fugar-candy. heneuth this ffraumi is a bed of hard done, confiding of large veins of flag, intermixed with feme rock-falt, the whole from twenty-five to ihirty-ifive yaros >n thicknefs. Under this bed is a fOebnd dratnm, or mine, of fair, from five to fix. yards thick, many parts of it per- feOly vvhite, and clear as crydal, others browner, blit all purer thah tlie. upper dratnm, yet reckoned not fd droiig. Above the whole mufs of fait lies a bed of whitidi clay, which has been iifed in the Liverpool eartjien >vare ; and in the fame place is found a good deal of gypfiim, or plalider-.done. Rock-lalt pit.s arefiink at great expence, and are very uncertain Tn their duration, being frequently dedroyed by the brine fprings binding into them, and difiolving the pillars, by which the whole work tails in, leaving vad chafms on the furface of the earth.' In forming a pit,,.a diaft or eye is funk, firailar to that of a coal-pit, blit more exteiidve. After the workmen have got down to the fait- rock, and made a proper cavity, they leave a fufficieiu fubdance of tlie rock, about feven yards in tliicknefs, to form a folid roof, and, as they proceed, they hew pillars out of the rock for the filpport of that roof, and then employ gunpowder to feparate wliat thev mean to raife. When well illiiniinated, the crydalline I'urfaceof the roof, pillars, and fides, of a large pit, make a glittering and magnificent appearance. I-redi air is conveyed from tlie month of the pit by means ot a tube, to whicli is fixed a pair of forge bellows, forming a continual current between the oufer air and that in the pit. Tire pits at the greated depth are dry, and of a comfortable temperature. 1 he larged rock-lalt pit now worked, is jn the towndiip of Witton, .and in the lands ot Nicholas .‘\lhton, Efq. It is worked in a circular form, 108 yards in diameter, its root fiipported by twenty-five pil- lars, each three yards wide at the front, four at the back, and it.u fides extending fix yards. The pit is fourteen yards holiow j con- feqiiently each pillar contains 294 (olid yards of rock-fah ; and the whole areaof the jiit contains 9160 fuperfjcial yards, little Icfs tliari two acres of land. . ^ average quantity of rock-falt unniiallv delivered from the pits in tlie neighbourhood of Nortliw idi for the lad feven years is 50,48.4 tons. Another account dates tlie annual average (no period men- tioned) ut about 65,000 toms. Upon this lad calculation, tjie mode in which the rock-falt is difpoied of is dated to be, exported to Dunkirk, Odend, Riga, Bruges, Niciiport, Pillati, Eifineur, &c- from 45 to 50,000 tons ; ditto to Ireland, from 3^00 to 4000 tons : refined in England, at Nortfiwich, 5000 tons; Liverpool, 3000 tons; iToddiatn, 3000 tons ; Dmigcoii works, 2500 tons. , VoL. IV. No. 50. E The$