B L A 



0, Logs on wliich the cheft is inverted, to preferve it from 

 the floor of the water receiver, from 12 inches to 18 of 

 fpace. 



Defcription of Plate XIV. Blnjl Furnace IVorh. 



Ground plan of an extcnfive blall furnace foiindery, con- 

 .filling of four furnaces and two blaft engines. The peculiar 

 conftruiftion of this plan h, that only one furnace may be 

 erected at a time, and afterwards the whole number ; fbll 

 preferving that regularity and uniformity of deljgn wliich 

 will at any time make the blowing machinery of one part 

 fubfervient to the whole, in cafe ol accidents, ftoppages for 

 repairs, &c. 



A, Engine houfc, with cylinder, pedellals, lever wall, 

 openings, &c. 



B B, Two boiler-feats and boilers. 



CC, Water regulators for the blall, which conveniently 

 communicates, by means of pipes, with the blowing cy- 

 linders, placed upon the pedeftals behind A, I. 



DD, &c. Centre line of the vi'liole blall pipes. This exten- 

 five column may be fo arranged, as to enable the furnaces to 

 be blown each with two tuyeres ; and the blaft of one engine 

 made to pafs through the whole. The general communica- 

 tion is cffefted by carrying the chief column either behind 

 the furnaces, or, as in the plate, through the main pillar 

 0/ the furnace, by means of an arched opening 3 feet 

 wide. 



E, Ground plan of the hearth, fquares, and pillars of four 

 blaft furnaces. 



FFFF, Bridge-houfes for materials, and filling or charg- 

 ing the furnace. 

 . GGGGG, Openings into the furnace top. 



H, Cafting-houfe. 



1, Second blaft-engine, upon the fame plan as A. Each 

 of thefe two engines ought to be calculated to blow two 

 furnaces, and occafionally, when any thing goes wrong with 

 one, the blaft of the other could be eafily diftributed for a 

 time among all the furnaces. 



BLASTED, in Antiqxul\\ fomething ftruck with a llajl. 



Among the Romans, places blafted with lightning were 

 to be confecrated to Jupiter, under the name of b'ldentalia, 

 and puteal'ia. It was alio a ceremonial of religion to burn 

 blafted bodies in the fire. 



BLASTING of J}on:s, in Jlgrirjture, the operation of 

 tearing afunder large ftones or rocks, which are in the way 

 of the plough or other inttruments employed in breaking up 

 ground, by means of gun-powder. The method of per- 

 forming this bufinefs is by boring a large hole, eight, ten, 

 twelve, or more inches deep, according to the nature and fize 

 of the ftone or rock to be blafled, by means of a chifel for the 

 purpofe, and then introducing a fufficient quantity of gun- 

 powder, and afterwards carefully ramming the hole up with 

 fmall fragments of ftone or other fohd materials, only 

 leaving a very fmall aperture, by placing a fteel pricker of 

 fufficient length and fuitable dimenflons, with a handle at 

 the top, at firft into the powder, and frequently turning it 

 round while the hole is ramming up. After the hole is quite 

 tilled, by forcing the hard materials in with a proper inftru- 

 ment, the pricker is withdrawn, and the aperture left by 

 it filled to the top with gun-powder, and then a match of 

 tow, ftraw, or other light inflammable material laid to it, 

 and fet on fire. 



It is obferved by Mr. Headrick, in the fecond volume of 

 ♦' Communications to the Board of Agriculture," that in 

 Older to perform this operation properly fome experience is 

 necclfary, and that a ik:Uul work.nan can frequently rend 

 iloiies into three equal pieces, without caufing the fragments 

 to fly about. This, he fays, depends upon the depth and 



8 



B L A 



pofition of the bore. It is alfo remarked, that n fmall por- 

 tion of qnick-lime, in fine powder, is toiind to increafe the 

 force, and confequently to diminifli t+ie cxpi-nce of Wafting 

 ftones. On thefe grounds the following is off'ered as a fub- 

 ftitute for gun-powder, which is now become very expen- 

 five, though, as is freely confcftt-d, without any experience of 

 its effctls. Suppofing_/^. I, Plate III. {/!j^rkti!ii:re)loht a 

 large ftone to be blafted or rent ; « ^, a bore ftnt dov.n into it iu 

 the ufual manner. This bore being then well cleinicd out and 

 dried, is to be .filled from ito c with the pureft quick-lime, or 

 fuch as fvv-ells moft in flaking. That it may be perfeftly quick, 

 it ftiould be taken red hot from the kiln, or the fmall furnace 

 where it has been burnt ; being then rammed in hard with 

 the jumper or punch ae, the upper part of the bore is to be 

 crammed with rotten rock in tiie ordinary way. The pricker 

 being removed leaves the aperture at b ; a b, a fmall pipe of 

 copper, of lefs diameter than the needle or pricker, having 

 an orifice about the dimenfionsof the ftraw, ufed to convey the 

 fire down to the gun-powder, with a funnel d to receive water, 

 is introduced into the aperture. Perhaps a ftraw or fmall reed 

 ftuck in the lower part of the funnel, among tallow or bees- 

 wax, might fcrve the purpofe of a copper-pipe. Things being 

 thus prepared, pour water into the funnel d ; and if the pipe 

 be not too high, fo as to prevent the air from efcapijig from 

 the aperture, left by the pricker, it will defcend and caufe 

 the lime to flake in the bore <: ^. Every one knows how 

 irrefiftibly the pureft quick-lime attrafts water, and with 

 what prodigious force it expands in flaking into three or 

 four timts its former bulk. From thefe data it is therefore 

 inferred, that the flaking of lime, in fuch circumftances, 

 would burft or rend the ftoneyin pieces ; but the fucccfs of 

 fuch an experiment, it is obferved, muft depend entirely 

 upon ufing lime of the utmoft purity, and having it very 

 ■hot, and perfeftly cauftic when it is put in. 



It is further remarked, that if the bore c i were filled with 

 water, and the aperture afterwards rammed up, the water 

 being made to freeze by cold, would rend the ftone ; for 

 when water paffes from a fluid to a folid form, it expands 

 with irrefiftible force, tliough froll cannot be depended upon 

 in this climate. 



BLASTOLOGY, from /9x«ro;, b^id, and ^M, I gather ; 

 the regular and flated pruning of vines. 



BLATNA, in Geography, a town of Bohemia in the 

 circle of Prachalitz, near which is an inland lake, which is the 

 fource of the river Uflava. 



BLATTA, in Middle Age Writers, denotes a purple in 

 the wool or filk, dyed with the liquor of the blatta. 



This was otherwife denominated blatta /erica, or blalloferl- 

 cum ; whence alio blaltiarhis, ufed in ancient writers for a 

 dyer in purple. 



Blatta, in Enlomcjlogy, a genus oi hymenopterous infefts, 

 called in England cccL-roaches, or blach beetles. The head 

 is inflected ; antenna; fetaceous; feelers unequal and filiform ; 

 wing- cafes and wings fm'ooth, the former fomewhat coria- 

 ceous ; thorax flattiih, orbicular, and margined ; legs formed 

 for running ; abdomen tenr.inating in two articulated ap- 

 pendages above the tail. 



The blatta:, confidercd in a colleftive point of view, arc a 

 very troublefome race of infefts. Certain kinds, that are hap- 

 pily for us flill peculiar only to the hotter parts of the world, 

 are fo formidable both in refpeft of number and talents for 

 doing mifcbicf, that they are really confidered as a peft to fo- 

 ciety in thole countries wliich they infcft. Thefe noxious crea- 

 tures enter houfesand commit various deprcdationson the fur- 

 niture, devour provifions of every kind, tear or gnaw holes in 

 clothe.Sj torment the inhabitants with their bite, and otherwife 

 do confiderable injury. The fort of blatta moft abundant in 



, England 



