Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/668

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foot or bottom of the hill, and is an opening of about fix foot long, and four foot broad, made in the fearch of a vein as deep as the fhelf ; this is a caution that muft be always carefully obferved, for if they are made lefs deep than this, they may mifs of the vein tho there is one. And the finking thus deep is always attended with certainty, for if no fhoad is found on this, it may be concluded there is none there ; except that fometimes it is found that the fhoad has been wafhed clean away, within two or three foot from the land : and then the load or vein is two foot farther or thereabouts up in the hill. If any fhoad is found in the eflay-hatch, there is a certainty of a vein of ore ; neither doth it add a little toward the making a conjecture how high up the hill, or how far off the vein firings or bonny is, carefully to mark how deep from the furface of the earth the fhoad lies, for this is held an infallible rule, that the nearer the fhoad lies to the fhelf or faft ground, the nearer the vein itfelf is, and vice verfa.

When there is no fhoad or appearance of a mine found in the firft eftay-hatch, if the conjecture of a mine being in the hill has any tolerable foundation, the tracing it does not end here; but they go ten or twelve fathom up the hill and there open a fecond efTay-hatch, and if no ore or fhoad-ftone is found in this, they go as many fathom on each hand at the fame height with the fecond hatch ; and there open a third and a fourth hatch, of the fame depth and dimenfions with the firft; if in neither of thefe there is found any fhoad- ftone, they afcend proportionably with three more hatches, if the fpace of ground require, at every ten or twelve fathom, and in this manner open them three abreaft, at twelve- fathom diftance up to the top of the hill. If no fhoad is found in any of thefe, it is concluded then that there is no tracing a mine there, and the hill is left. If any fhoad is found in any of thefe hatches or openings, the afcending hatches from this are kept on in a direct line, and the deeper the fhoad lies the nearer the vein is. The fhoad grows gradually deeper from the furface, but nigher the fhelf as they approach the mine ; as fuppofe it be but half a foot from the fhelf and (even foot deep from the furface, the vein is then concluded to be within a fathom or two ; and on this the firft proportion of twelve fathom between every hatch is leflened, to fix, four, two, one, or even lefs than that, as the vein is conjectured to be more and more near. It often happens, for want of a good guefs in this matter, that the diggers over-fhoot the load ; that is, they open their next hatch too high up the hill, or above the load or vein : this is a miftake eafily difcovercd and eafily rectified. If a fhoad is found lying near the fhelf in one hatch, and in the hatch above there is no fhoad at all, it is a proof that the hatch is too high, and the remedy is only to fink a hatch at a middle diftance between the laft two, which will probably fall upon the very point of the load, and finifh the work of tracing. Sometimes it happens, that in continuing the tracing of the firft fhoad, a fecond or new one is found ; it is not uncom- mon for two fhoads to be thus found in one hatch, and this is eafily difcovercd without any danger of miftake ; for fup- pofe in the laft hatch the fhoad which they trace lay at eight foot deep, and in this it lies at ten foot, and befide this there is a fhoad found at two foot depth ; it is very certain that the fhoad at ten foot deep is the fame they were before tracing, and this is a new one pointing to another vein or load, which is now firft difcovered fo near the furface of the earth. This has generally gravel or earth mixed with it, and is to be carefully examined ; when the higher hatches are opened, this is continually found as well as the old load ; and when the firft is traced to the point of the vein, this fecond is to be continued in the fame manner, by other hatches opened at the fame diitanccs above : it often happens that in tracing this fecond fhoad, the hatches dug for it difcover another new one or a third fhoad ; all thefe are to be traced one over the other by the fame hatches, and will all be found worth the feeking after. The old writers on mineralogy agree with us in this obfervation, and tell us, it is not uncommon in fome places to find as far as feven loads lying parallel to one another in the fame hill. In thefe cafes, however there is ufually one mafter-load, or grand vein; the other fix, that is three on each fide, being the leflcr or concomitant veins. Five in the fame manner, fometimes lie in this order, the grand load in the middle and two on each fide, but the more com- mon method is three, a large one, and two fmaller. Every load has a peculiar coloured earth or grewt about it, which is found alfo with the fhoad, and this always in a greater quantity the nearer the fhoad lies to the load, and be- comes leflened by degrees to the diftance of about a quarter of a mile, further than which that peculiar grewt is never found in any quantity with the fhoad ; fo that this is a proof that the load or vein is near when it is found in quantity. A valley may chance to lie at the foot of three feveral hills, in fuch a manner, as to contain three feveral grewts, or that earth which was moved with the fhoad in the concuffion of the ftrata at the deluge, with as many different fhoads or Trains of fhoad-ftones in the midft of each: in this cafe it will be very ncceflary to know the caft of the country, and ef each hill in refpeft to its grewt, for the furer training oi~

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tliem one after another as they lie in order: according to the foregoing rules of dray-hatching, the uppermdft in tffis cafe always directs which hill to begin with firft. It fometimes happens, that after having trained the fhoad found in a valley up to the upper parts of a hill, there is only a fquatt, or bonny found inftead of a right vein of ore, for thefe detached parcels of ore have their fhoads as well as the right veins. Thefe are ufually about two or three fathom long, and a fathom broad ; few of them are larger, moft lefs and they never communicate with any other lead or vein) nor ever fend forth any of their own. The extremities of thefe beds of ore terminate without fending out any ftrongs not lying within walls as the loads ; but tho' they are in the fhelf or fait ground, not moved by the flood, their furface is equal every where with that of the imaginary flielfy one, and they go down five or fix fathoms deep and there terminate at once. The ore contained in thefe are rich, and they are al- ways wrought out to the confiderable advantage of the owners.

Thefe are the general rules of tracing mines, and tho' fome- what tedious and expenfive, they are certain, and never lia- ble to the error and disappointment the other fliorter ways as they are called, are liable to. Thefe ftort ways are by the virgnla divmatorm or the hazel-wand, whofe bending in cer- tain places without any external vilible force, is to point out the place where the vein of ore lies : the waters thought to lffue from the particular loads are alfo ufed by fome as afhort means of finding the veins; other of thefe ways are alfo by mineral fleams and effluvia, by the barrenness of the foil, and the pitching of noflurnal lights on the fiippofed orifices of mines. But thefe methods are too extravagant or too uncertain to be ufed in cafes of fo much confequence. When the mine is found by the more certain rules of tracing, the digging it is a matter of lefs difficulty. Phil. Tranf. N\ 60. See the ar- ticle Digging.

TR AMELLED, in the manege. A horfe is faid to be tramelkd, that has blazes or white marks upon the fore and hind foot of one fide ; as the far foot before and behind. He is fo called from the refemblancc tire white foot bears to a half traincl.

G'o/j-Tramfi.led Horfe, is one that has white marks in two of his feet that (land crofs-ways. like St. Andrews crofs ; as in the far-fore-foot, and the near hind foot, or in the near foot before, and the far-foot behind.

TRAMMELS, a kind of net ufed in fowling, the defcription of which fee under the article Lark.

ERAMIS, a word ufed by fome medical writers, to exprefs the line running along the middle of the fcrotum, from the penis to the anus,

TRANCHEFILE, in the manege, the crofs chain of a bridle that runs along the bit-mouth, from one branch to the other

TRANSCENDENTAL (Cj*/.)— Transcendental dfi mslogy. SeethearttcIeCoSMOLoGY.

TRANSFORMATION {Cycl.)— Transform ation ,f In- put. It is well known that (lies are not produced in that form, from the eggs of their parent fly, but undergo a change like that of the butterfly, and the like winged in- fers ; the egg hatching into a worm ; and this afterdating, and performing all tire operations of animal life for a certain time, enters into a ftate of reft, and thence is changed into a fly. D

Though the general courfe of nature is the fame in this re- fpea in flies and butterflies, yet the means and manner of it are different; the butterfly makes ils coat for this trans- formation ; the fly-worms of many kinds have only a {hell of their own proper ikin to undergo this change in All the fly-worms of the firft and fecond, and many of thofe of the third clafs, have their cafe thus made only of their own (km; the different fpecies afford indeed fome varieties in the manner of this, but a general idea of the work may be had from obferving the worm or maggot of the common flefh-fly in its feveral itages.

When this creature has arrived at its full growth, It finds it not convenient any longer to remain among the food it has till then lived upon; it quits it and now goes in fearch of a place where it may wait for its metamorphofis. To this pur- pofe it creeps into the earth, where it remains two or three days without any change ; at the end of this time, inflead of its pointed figure, its white colour, and foft Hefty fubftance, it acquires the figure of an egg, and becomes of a chefnut colour, or fomewhat redift, and looks opake and cruftaceous ; • it is in this ftate perfeaiy ftiff, and drftitute of motion, and' the creature (eems not only to have loft its form, but wholly to have loft its life alfo. Reaumur's Hift. Inf. Vol. 4. p. 288. This however is not the cafe, all that is done, is that the creature has abfolutely quitted its (kin, which is now become hard and of a determinate fieure, and is within it compleat- mg all its changes. Ibid. p. 289.

The manner in which this change of feure is given to the fkin, is by the creature's drawing its head, and the two or three firft rings of its body, within the reft, and by that means making itfelf of this fhape, (holt and equally thick at each end. It does this within a few hours after it creeps into the earth, and if taken out after that time is always found of this fhape, and feems to be transformed, only that its ikin has not yet ac- ° quired