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Mr. C. Wye "Williams was one of the earliest, as he has been the most pertinacious and consistent, advocate of the introduction of a large additional volume of air into the furnace, and we have to thank him for the labour he has expended in proving the necessity for air as one of the prime conditions of economy of fuel and success in the prevention of smoke. Mr. Wye Williams contends for a uniform admission of cold air to the furnace, relying upon frequent thin feeding to equalise the needs of the furnace. The peculiar principle of his plan is the mechanical division of the air by causing it to enter the furnace through what he terms a diffusion plate, or partition perforated with numerous small apertures. This is usually placed behind the bridge where the gases needing combustion pass into the flues. There is no doubt this is a convenient method for the introduction of air, and has in many instances effectually prevented the formation of smoke.

Mr. Syme Prideaux contends for a variable admission of air, greatest when the fuel is first thrown on, and decreasing to the ordinary supply through the grate-bars as the fire burns clear. For this purpose he constructs his furnace doors with metal Venetians, which open by a self-acting apparatus when the fuel is supplied. They then gradually close at a regulated speed, altogether independent of the care of the fireman. The air entering through the door is, by an arrangement of plates, warmed as it enters the furnace, and carries back the heat radiating from the door.

All these systems are more or less effective, but I am inclined to think that a judicious engineer, with a careful stoker or fireman, will effect all the objects to be attained with the means placed at his disposal, in a well constructed boiler of sufficient capacity, and with a simple furnace such as has been described in the foregoing chapter, as completely as can be done by any one of the numerous nostrums held forth as the only antidotes for smoke, and promising great economy of fuel.

CHAPTER IX.

On WInDMILLS.

Atmospheric Disturbances causing wind have from a high antiquity been employed as a motive power, and probably the earliest application of this force was the propulsion of ships by sails. Amongst the most primitive races, long before we made much progress, this power was applied in the navigation of small vessels; and the ancient Phoenicians, Greeks, and Romans were all of them well acquainted with this mode of employing the force of the wind for purposes of human industry. It is to be regretted that we have no records of the time when it was applied as a motive power in mills; this event is lost in the oblivion of the past, and it was not till early in the thirteenth century that we find the Dutch and French employed in the construction of windmills adapted to the wants of an energetic and industrious population. These times were marked by a growing intelligence that encouraged and fostered inventive talent, and the Dutch millwrights and engineers were long celebrated for their skill and knowledge in every art that had for its object the improvement of the industrial resources of the people.

The following account of their ancient history as far as our knowledge extends, may not be uninteresting to the general reader.

'When were windmills introduced into England? The Romans had hand, and cattle, and water mills; but "it is very improbable, or much rather false," says Beckmann, " that they had windmills;" nor does there seem to be any sufficient ground for the common notion that Europe derived its windmills from the Saracens through the Crusaders.

'It is after or about the date of the Norman Conquest that we begin to hear mention of mills moved by wind in this quarter of the world. "They were first known in Spain, France, and Germany," says one of the authorities quoted by Haydn, "in 1299." When were they first known in England? The " Boldon Book" of 1183 has frequent mention of mills—as, for example, .when it speaks of our sister-borough at the other end of Tyne Bridge: "Gatesheued, cum burgo et molendinis, et piscariis et furnis, et cum tribus partibus terrse arabilis de eadem villa, reddit lx. marcas." (" Gateshead, with its borough and mills, and fisheries and bakehouses, and with three parts of the arable land of the said town, renders 60 marcs." But there is no direct description of the kind of mills which were in use. We are not left, however, without some clue. "William," we are told, "holds Oxenhall: to wit, one ploughland and two cultures of the territory of Darlington, which Osbert de Selby used to hold to farm, in exchange for two ploughlands of land at Ketton," &c. &c.: "debet etiam habere molendinum equorum." (" He ought also to have the horse mill.") And, again, "Guydo de Redwortha * * * operatur ad stagnum molendini, et vadit in legationibus Episcopi." (" Guy of Redworth works at the mill-dam, and goes on the bishop's errands.") So that there were horse and water-mills in the time of Bishop Pudsey; but the "Boldon Book" affords us no glimpse of a windmill, with its revolving wands, lending a picturesque air to the scenery of the bishopric. In the volume, however, before us, containing Hugh Pudsey's survey of the county palatine (edited for the Surtees Society by the Rev. William Greenwell), there is also a roll of receipts and expenditure of the 25th year of Bishop Bee (1307), wherein, among repeated mentions of mills, there is specified distinctly, not only a water, but a windmill : — " Refectio Molendvriorum. — In refectione molend' de Heighinton', 71s. 8$d. In ref. molend'de Northaukland, 24s. In ref. moln' fullon' ibidem, 19s. 7d. In refn. moln' de Wolsingham, 100s. 2d. In refn. moln' de Cestr', 12s. 7\d. In ref. moln' de Gatesheued, 13s. 6d. In refn. moln' de By ton', 10s. In uno novo molendino aquatico facto apud Brunhop', 119s. lOd. * * In refn. moln' de Norton' ad tascam, 318. 8d. In solutione facta Roberto de Tevydale carpentario pro meremio colpando ad j. molendinum ventriticwm faciendum apud Norton', 20s." Have we not here a Scotch carpenter (we may not call him a millwright) cutting wood to make a windmill at Norton, and receiving twenty shillings for his job? It is evident, then, that one windmill, at least, came into existence in the bishopric so early as 1307 ; and we must not rashly draw any larger conclusions. We must not conclude that there was only one. The sites of some of the other mills mentioned in Bishop Bee's roll, it has been suggested to us, would seem to point to wind as the moving power. There is, for example, the mill at "Clivedon" (Cleadon). (" Firmce Molendinorum. — De moln' de Boldon', Clivedon', et Wyteburne, £8 16s.") And there can be little doubt that in other parts of England (and not improbably in our own) windmills had for a considerable time been enlivening our landscapes. Long before 1299 (the date assigned for their simultaneous introduction into France, Spain, and Germany), Don Quixote might have tilted with the four-armed giants of France and Britain. "Mabillon," says Beckmann, " mentions a diploma of 1105 " (when the Crusades were in their early infancy), "in which a convent in France is allowed to erect water and wind mills (rnolendina ad ventum);" and " in the year 1143, there was in Northamptonshire an abbey (Pipewell), situated in a wood which, in the course of 180 years, was entirely destroyed ;" one cause of its destruction being said to be, " that in the whole neighbourhood there was no house, wind or water mill built, for which timber was not taken from the wood. (Dugdale, Mon. i. p. 816.) The letter of donation, which appears also to be of the twelfth century, may be found in the same collection (ii. p. 459). In it occurs the expression molendinum ventriticum. In a charter also, in vol. iii. p. 107, we read of molendinum ventorium. (See Dugdale's Monasticon, ed. nov. vol. v. p. 431, 442.)"

'From this it appears that we did not get our windmills from the Saracens; and the probability is that we had them on this side of Europe before they came into use on the other. It was not till 1332 that Bartolomeo Verde proposed to the Venetians to erect a mill to go by wind; and a site was only granted to him on condition of its surrender if his experiment should fail. Windmills were probably scant at the close of the eleventh century, when the Crusades broke out; but in the twelfth they began to be more common, and "a dispute arose whether the tithes of them belonged to the clergy "—a question which Pope Celestine III. very naturally, and not unreasonably, determined in favour of the Church.'

An ingenious writer in the Practical Mechanics' Magazine states that'About seventy years ago, a master mariner, residing at Dunbar, in Haddingtonshire, devised a novel windmill on the horizontal construction. It consisted essentially of an upright shaft, which carried four arms, at the extremities of which were four masts, rigged with trysails, and the sheets were adjusted so that the sails might take their proper positions, according as they were acted on by a beam wind, "booming out," or coming up in the " wind's eye." A mill so constructed would not possess the important element of durability, as the violent jerks imparted to the sheets would very soon snap them. Several mills on the horizontal construction were in use at the town of Eli, in the litigious kingdom of Fife, at the end of the last century, and were employed in grinding indigo; but they have long since been removed.

'In the twelfth century, when windmills began to be more common, a dispute arose whether the tithes of them belonged to the clergy, and Pope Celestine III. very considerately decided the question in favour of the Church.

'About three or four centuries ago, the avaricious landholders, favoured by the meanness and injustice of Government and the weakness of the people, extended their regality or kingship not only over all streams, but also over the very air, and mills which it impelled, so that small proprietors, before erecting a windmill upon their own property, had first to obtain permission from the superior of the province before doing so.

'The early mills were immovable, and could only work when the wind was in one quarter; they were afterwards placed, not on the ground, but on a float which could be moved round in such a manner that the mill should catch every wind. This method gave rise, perhaps, to the invention of movable mills.

'To turn the mill to the wind, two methods have been invented, and are in common use: in the one the whole structure is arranged so as to turn on a post below; and in the other the roof alone, together with the axle arid the wings, is movable. Mills of the former kind are called German mills, those of the latter, Dutch mills. They were both moved round either by a

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