T 1 L 



T I L 



it to bcud or i"p)in,<r every time tlio tail (/of the hammer 

 llrik.L-s upon it, aiid this aids the rccoihng adlion very 

 much. 



The axis on which the hammer moves is formed by a 

 niK^ of call-iron, through which the helve of the hammer 

 is put, and held fall by wedging round it. The ring has 

 a proicfting trunnion on each fide, ending in an obtufe 

 conical point, which is received in a focket firmly fixed in 

 the hirll -frame ^/; by fcrews and wedges, one of vi'hich is 

 fecn at ;•. Thefe two fockets arc thus capable of adjnft- 

 mcnt, fo as to make the hammer face fall flat upon the 

 anvil. The three wheels K, I, H, are of different fizes and 

 numbers of cogs to produce that velocity in each hammer 

 which is beft adapted for the work it is to perform : thus, 

 the wheel K for the great hammer has eight cogs, and there- 

 fore produces eight blows of the hammer for each revolu- 

 tion of the fly-wheel ; the wheel I for the middle hammer 

 has twelve cogs ; and the wheel H for the finall hammer 

 fixteen ; the latter will therefore make two llrokes for every 

 one of the great hammer. In fixing the three wheels upon 

 the great {liaft G H, care is taken that they fliall produce 

 the blows of the different hammers in a regular fuccefTion, 

 and equalize as much as poffible the force which the water- 

 wheel mufl exert. The wheels are fixed upon the {haft 

 by means of a wedging of hard wood, driven in all round ; 

 the wood, being capable of yielding a little to the fhocks 

 occafioned by the cogs meeting the tails of the hammers, 

 renders the concuffions lefe violent. 



The following are the principal dimenfions : 

 The head of the great hammer, P, weighs 35cwt., and it 

 is intended to make 150 blows /tv minute: it is lifted 17 

 inches from the anvil at every blow. 



The middle hammer, M, is 2cwt., and makes 225 blows 

 per minute: it is lifted 14 inches each time. 



The fmall hammer, N, weighs ijcwt., and makes 300 

 tlows per minute : it is lifted only 1 2 inches. 



To produce thefe velocities, the great axis G mtift make 

 l8|- turns ^fr minute ; and the cog-wheels E and D, being 

 in the proportion of one to three, the water-wheel mufl 

 make 65 revolutions fer minute ; the water-wheel being 

 18 feet diameter, its circumference will be 18 x 3.1416 = 

 56.54, or 56^ feet : this multiplied by 6.25 is about 353 feet 

 motion per minute, or divided by 60 = 5.9 feet motion ^cr 

 fecond for the circumference of the water-wheel. 



The tilt-mills employed in the manufatlure of fleel, do 

 not have the great hammer P, but the largefl they ufe is 

 about the fize of that at M, and is adapted for welding 

 faggots of fleel to make fhear fleel : the other two hammers 

 are about the fize of N, and are made to work much 

 quicker, viz. from 350 to 400 blows j!ii?r minute. This is 

 very eafily iiccomplifhed by making the wheels E and F as 

 I to 4, inflead of i to 3, as fhewn in the drawing. 



TILTH, in Agriculture, a term ufed to fignify the con- 

 dition of the earth or foil after the land has been ploughed 

 and broken down by the harrow or other tool of the fame 

 kind ; or the ftate and circumilances of the ground in regard 

 to tillage, or heart, as relating to manure. Thus we have a 

 good and iml tilth, as well as land in and out of tilth, in 

 works on agriculture. 



TILTIL, in Geography, a town of Chili ; 30 miles S.E. 

 of Valparayfo. 



TILTING 0/ Steel, the procefs by which bliflcred fleel, 

 or fleel in the raw flate, rs rendered duftilc and fit for the 

 purpofes of various manufaftures. Tilting confifls in ham- 

 mering or forging the fleel by a large hammer called a tilt. 

 See TlLT-Nanimer. 



Steel is formed by two proceffes : one in which it is 

 made at once from pig or erude iron in the finery, nearly in 



10 



the fame manner as making bar-iioa : this is called natural 

 fleel. In the fecond procefs, malleable iron, in bars, is im- 

 bedded in charcoal or other carbonaceous matter, and ex- 

 pofed to a confidcrable heat, till the carbon is thought to 

 have penetrated fufficiently into the iron to have changed it 

 into fleel. This is called converting the iron by cement- 

 ation with charcoal ; and the furnace in which the operation 

 is performed is called a converting furnace. 



The objeiil of this procefs of cementation, is to impreg- 

 nate the iron with a certain quantity of carbon, to be derived 

 from the charcoal : like many other fimple opcratioiis, iL 

 requires great care and nicety to perform it properly, when 

 put in pradtice on a large fcale. The iron mufl be expofed 

 to the aftion of an intenfe heat in contadl with carbon (but 

 defended from the accefs of oxygen), until the iron imbibes 

 a portion of carbon and becomes fleel. 



The quantity of carbon which mufl be combined with 

 iron to produce fleel, admits of confiderable latitude, and 

 tlie qualities of the fleel vary in the fame proportion : with 

 too little carbon, fleel will be foft ; and not fufficiently hard 

 when it has been fuddenly cooled by plunging in water. It 

 has a rough and fomewhat fibrous frafturc, and in general 

 may be faid to pofFefs many of the qualities of malleable 

 iron. On the other hand, in proportion as the quantity of 

 carbon is diminifhed, an over-cemented fleel, containing an 

 excefs of carbon, is brittle, eafily fufible, exceffively hard 

 after being fuddenly cooled, and is hable to crack on the 

 fudden change of temperature from hot to cold. All thefe 

 properties are an approach to crude iron. 



The received opinion refpedting fleel and the beft caft- 

 iron is, that they have the fame conftitiient parts, but in dif- 

 ferent proportions ; the former containing a fmaller propor- 

 tion of carbon than the latter. All the crude or cafl-iron of 

 commerce contains oxygen in greater or lefs proportion, but 

 the beft fleel is fuppofed- to be nearly free from this. Mr. 

 David Mufhet, whofe great praftical and theoretical know- 

 ledge entitles his opinion to the greatcft refpeft, fuppofes 

 that the carbon contained in caft-iron and in fteel, exifls in 

 very different ftates ; and that fteel is a combination of iron 

 with pure carbon, fimilar to the diamond, but that crude 

 iron, is iron containing the oxyd of carbon, which is char- 

 coal. This opinion he founded upon the refult of a very 

 numerous feries of experiments, many of which he com- 

 municated to the Philofophical Magazine, vol. xiii. He 

 found that a piece of Swedifh bar-iron, weighing 885 

 grains, introduced into a Stourbridge clay crucible, and half 

 its weight (442 grains) of charcoal well prepared; a clay 

 cover, fitting exaftly, being placed on, and the whole ex- 

 pofed to a moderate heat for half an hour ; that the refult was, 

 a perfeft button of fuper-carbonated crude iron, weighing 

 928 grains, which therefore had gained -r'.ith on its original 

 weight ; while the charcoal, which remained in the crucible 

 in an intenfely black ftate, weighed 290 grains, having lofl 

 34.4 />fr cent, of its original weight. 



In a fecond experiment, made in a fimilar manner, but with 



onlya quarter of the charcoal, the iron gained of its ori- 



ginal weight, and the lofs in charcoal was 45 per cent. : the 

 metal was richly carbonated. When one-fixth of charcoalwas 

 ufed, the iron produced, refembled the produce of No. 1 . and 

 2. of the crude iron of commerce ; its weight was increafed 



■ ; and 57 per cent, of the charcoal difappeared in the 



pjrocefs. 



With one-fciehth of charcoal, the iron gamed of its 



origiual 



