T I L 



the- (licltf riug of paffengers. Sucli arc fome of tliofe wliicli 

 tarry paflciigers botwct-u London and Gravcfend. 



TiLt-I/ammrr, is a large and heavy hammer, adapted to 

 ho pnt Ml rapid motion by the power of a water-wheel or 

 lU'amH-ngiiie. 



TIk- lilt-hammer is diftinguiflied from the lift-hammer, 

 or fiirge-hammer, by the manner in which it is lifted up 

 by the cogs of a wlieel which is turned by the mill. 



The forjre-hammer is mounted on a centre of motion at 

 the extremity of the haft or helve of the liammer oppofite 

 to the head of the hammer, and the cogs of the wheel ope- 

 rate beneath the helve near the head, to lift or tofs up the 

 liammer againfl; a ftrong wooden fpriiig called ttie rabbit, 

 which is firmly fixed over the head of the liammer. This 

 fpring refleds the hammer down upon the anvil with greater 

 force and fmartnefs than the hammer would defcend by the 

 aftion of gravity alone. A lift forge-hammer is defcribed 

 under the ai-ticle Iron. See P/ale IV. Iron Manufadure. 



The tilt-hammer is poifed on pivots or a centre of motion, 

 which is about the middle of the length of the helve, or 

 fometimes at two-thirds from the head. The cogs of the 

 wheel are made to aft on the tail of the helve beyond the 

 centre of motion, and they prefs down the end of the tail, 

 and thus caufe a correfpondent elevation of the head of the 

 hammer. Sometimes the fpring is placed over the head of 

 the hammer, the fame as a lift -hammer ; but more commonly, 

 the tail of the hammer is made to flrike againll a fixed floor ; 

 and when the head of the hammer is thrown up fuddenly, 

 the momentum given to it caufes the head to rife up after 

 the tail ftrikes the floor, and thus bends the helve, which by 

 its elafticity caufes the head of the hammer to defcend 

 fmartly upon the anvil. 



The till-mills in the neighbourhood of Sheffield are very 

 fimple : they are worked by a fmall water-wheel, upon the 

 axis of which is a wheel with a great number of cogs, fixed 

 m its circumference. Thefa fuccefiively deprefs the tail of 

 the hammer, and raife its head : the hammer falls by its own 

 weight, aided by the fpring of the helve, upon the hot 

 metal. The fizc ot the water-wheel, and the number of 

 cogs in the wheel, are adapted to produce from three hundred 

 to four hundred ftrokes per minute. 



This great number requires the water-wheel to move with 

 a velocity which is inconfiftent with the beft mode of apply- 

 ing the fall of water, becaufe it is well known that water, 

 as well as any other heavy body, can only defcend with a 

 certain fpecd. If, therefore, the floats of the wheel are re- 

 quired to tiu-n with a great rapidity, it is evident the pro- 

 portion of work the wheel will perform, will be but fmall in 

 proportion to the quantity of water expended. For this 

 reafoQ, it is found to be a great improvement in till-mills to 

 add cog-wheels which will give the hammers a fufficient 

 velocity, while the water-wheel turns at fuch a rate as is found 

 to produce the greateft power from a given quantity of 

 water. 



A capital mill of this kind is delineated in PlateVlll. 

 Iron Manufaciure. It was made at the Carron iron-works 

 in Scotland, after defigns of the celebrated Mr. Smeaton. 

 It is adapted for forging iron into bars, and has three tilt- 

 hammers of different powers for different kinds of work. 

 Thefe hammers arc not made to ftrike fo quick as is ufual 

 in the Sheffield mills for the tilting and drawing out fteel 

 bars ; but by giving a greater number of cogs to the wheels, 

 the rcquifite rapidity may be obtained without increafing the 

 fpecd of the water-wheel. A capital mill was built at Shcf- 

 hcld about fix years ago, which is on Mr. Smcaton's plan, 

 except in the proportions of the wheels, and its performance 

 IS luperior to any of the other tilt mills. 



T I L 



A A, in the plan ^^. i. are the walls of the building; 

 B B the great water-wheel, which is of the kind called a 

 breaft-wheel. [Sec W ATER-lVheel.) It is 1 8 feet diameter 

 and 5 feet broad. The total defcent of the water which ac- 

 tuates it is 7 feet 2 inches, and it falls upon the float -boards 

 rather below the centre of the wheel, being retained againil 

 the floats by what is called the brcafting, that is, a fweep or 

 curved wall of mafonry, which is accurately adapted to the 

 float -boards of the wheel, and as clofe to them as is poffible, 

 to avoid touching. 



The axis C of the water-wheel is carried through the 

 wall A, and on the extreme end of it is a large iron wheel 

 D, of 90 wooden teeth, 9 feet 6 inches diameter. This 

 turns a pinion E of 30 teeth, and 3 feet 2 inches diame- 

 ter. The pinion is fixed on one end of a cafl-iron axis 

 G G, whicli is made very large, for ftrength, and hollow 

 within, like a pipe. The gudgeons b and G are fixed into it 

 at each end, and upon theie gudgeons it revolves. F F is a 

 cafl:-iron fly-wheel, fixed on the axis clofe to the pinion ; it 

 is 12 feet diameter, and the rim 6 inches by 5. The 

 weight is very confiderable, and gives it a momentum to 

 regulate the motion of the whole mill, and equalize all irre- 

 gularities which arife from the facceffive aftions of the mill 

 to raife the three hammers, L, M, and N. 



Each hammer has a feparate cog-wheel, K, I, and H, to 

 give it motion, which is eff^efted by the cogs of thefe wheels 

 atling upon the tail; of the hammers and preffing them down. 

 This is explained by the elevation^^. 2. where e is the iron 

 head of the hammer, / its centre of motion, and d the tail 

 or extreme end, upon which the cogs of the wheel aft, and 

 which is plated with iron on the upper fide, to prevent it 

 from wearing. 



P is the anvil-block, which muft. be placed on a very firm 

 foundation, to refifl the inceflant fhocks to which it is fub- 

 jefted : the centre, f, or axis of the hammer, is fupported 

 in a call-iron frame, gh, called the hirft. When the cogs 

 of the wheel ftrike the toil of the hammer fuddenly down, 

 and raife the head, the lower fide of the tail of the hammer 

 ftrikes upon a fupport n, which afts to ftop the afcent of 

 the head of the hammer e, when it arrives at the defired 

 height ; but as the hammer is thrown up with a confiderable 

 velocity as well as force, the effort of the head e to con- 

 tinue its motion, after the tail ftrikes the ftop n, afts to 

 bend the helve L of the hammer, and the elafticity of the 

 helve recoils the hammer down upon the anvil with a re- 

 doubled force and velocity to that which it would acquire 

 from the aftion of gravity alone. 



To obtain this aftion of recoil, the hirft gh muft be 

 held down as firmly as poffible ; and for this purpofe, four 

 ftrong iron bolts are carried down from the four angles of 

 the bottom plate h, and made faft to the folid bafis of ftone 

 R R, upon which the whole refts : upon this bafis are 

 placed four layers of timbers, i, h, /, m, which are laid one 

 upon another, and the timbers of each layer are laid crofs- 

 ways over the others. Each layer confifts of ievcral pieces 

 laid fide by fide, and they are flightly treenailed together, 

 to form a platform. Each platform is rather lefs than that 

 upon which it refts, fo as to form a pillar of folid timber ; 

 on the top of which the hirft-frame ^ ^ is placed, and 

 firmly held down by the four bolts, which defcend through 

 all the platforms, and have fecure faftenings in the folid 

 mafonry beneath. 



The ftop n is fupported by a fimilar pillar, but fmaller, 

 and compofed of three layers : the upper piece n, which is 

 feen crolTways m Jig. 2, is about tliree feet long, and the 

 under fide is hollowed, fo that the piece bears only upon 

 the two ends, leaving a vacancy beneath it, which occafions 



it 



