ful than raising the sluices, because they admit of being larger, and require no attention to watch the tide; but, he says, they are also defective in not admitting masted vessels, when they are placed under the dyke, and in not retaining water to scour the channel.

3.-"The third kind of sluices, serving to pass masted vessels, are made with two pair of pointed doors, like the second, but raised as high as the dykes themselves, and comprising between them a receptacle for ships; and with two small sluices, either made in the walls, or in the doors themselves. Then he describes briefly, the mode of passing a ship through the locks.

"Besides these, others have been made which open of themselves, with the ebb falling on the bed, and rise with the flood; also gates which are drawn aside into the land, but they are not convenient.

"Stevinus also informs us, that he and several other engineers had agreed to study this subject, and communicate their inventions to each other. The following was the result:

"Adrian Janssen, a carpenter, of Rotterdam, invented the locket, for holding a turning-gate in its place. A turning gate had been made at Briel, which was retained in a groove at the bottom, out of which it was wound three inches high by a rack ere it could turn into the line of the

stream.

"Stevinus's mode was, to have rising vanes, the whole length of each abutting lock gate; Cornelius Dirricksen Muys, of Delft, to have second lock gates, holding up the first; and Adrian Dirricksen, of Delft, improved Janssen's mode, by applying them in folding gates. He got a patent for it from the States, and built two at Maeslandsluis, and two at Helvoetsluis, of that kind, and which yet exist. Stevinus's whole account of this mode of securing harbours is well worthy of attention."

"Of the Italian authors, the first who enters into the

history of this discovery is Zendrini, in his treatise Della Acque Corrente, published in Venice, 1746, who says, that being interested in ascertaining the original inventors of locks, he had taken some pains to search the Venetian annals on the subject, and found that the first lock was invented at Stra, near Viterbo, by two brothers, named Dominico, clockmakers in Viterbo, who had a patent for its construction from the Senate of Venice, in the year 1481. The patent describes, that these engineers had engaged to construct a sluice (concha) in which boats might pass without danger; and which being so contrived, that the water passing out with facility, the vessels would neither require to be discharged, nor drawn over. This account has been acquiesced in by Lalande, and other writers; but Lecchi, in his book, Dei Cannali Navigabili, alleges that, previous to this period, in 1420, the lock had already been introduced in the navigation of Milan, by Fillippo Maria Visconti, as mentioned in his life, by Decembris, one of his courtiers. And 1188, Petentino, the architect of Mantua, had thought of it in his dykes on the Mincio, at Governólo, the first attempt at overcoming the fall of rivers in all Italy: so that Lecchi claims it for Lombardy. Nevertheless, there is every reason to believe, that these cases were nothing more than the wear, and single flood-gates, already used for the navigation of rivers; for Bertazzolo, in his discourse upon the sluice of Governolo, published at Mantuà, in 1606, proposes a lock with a chamber (sostegno) to be built at the sluice of Governolo, as a new thing. This lock has since been established on the left bank of the Mincio; and connected with an opening wear, it serves to hinder the turbid waters of the Po from filling up the lake of Mantua; while, at the same time, it preserves the navigation. Indeed, in many parts of Lombardy, wears with flood-gates are yet employed for river navigation, although lock's exist of an early date, and some of them also of a singular magnitude and boldness.

To conclude, we may observe, that at all events, a very few years after the supposed invention in the Venetian State, the celebrated painter, architect, and engineer, Leonardi da Vinci, in 1497, applied locks to connect the Milanese canals, derived from the Adda and the Tesino.

"We must next consider the claims of Holland, that other great cradle of the hydraulic art of Europe. We have formerly noticed that the embankment of the different districts of Holland had chiefly taken place between the years 1000 and 1400. In 1235 a placart was granted by William, Earl of Holland, to the city of Haaerlem, for the construction of the sluices of Sparendam. Those sluices must have necessarily been a lock; for it is expressly said to be constructed for the more convenient passage of ships, and a toll is appointed to be collected on the vessels which make use of it.

"About the same time, viz. 1255, the jurisdiction of Deftland was established, and the ancient canal from thence to Leyden completed. On this canal, at the separation between Deftland and Rhineland, is the basin of Leidsendam, which, as we have already observed, becomes, to all intents and purposes, a complete lock, by means of the stop-gates belonging to the two jurisdictions at either end; and it has always been used as such.

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"At the same period the citizens of Utrecht had formed an aqueduct from the river Lech, at Vreeswyck; and in 1371, as we are informed by Hada, in the history of Utrecht, they deepened and enlarged this aqueduct, so as to make it navigable; and placed at the bank of the river Lech double flood-gates, or stop-gates of timber, by which the waters might be more easily kept out, or introduced. (Hedæ, Hist. Epist. Ultraj. Arnold ii. Episc.).

(To be continued.)

LIST OF PATENTS FOR NEW INVENTIONS

Which have passed the Great Seal since March 26, 1829.

To William Church, of Bordesley Green, in the parish of Aston, in the county of Warwick, Esquire; for certain improvements in buttons, and in the machinery or apparatus for manufacturing the same. Dated March 26, 1829.-To be specified in six months.

To William Madeley, of Yardley, in the county of Worcester, farmer; for an apparatus or machine for catching, detecting, and detaining depredators and trespassers, or any animal; and which he denominates the Humane Snare. Dated March 28, 1829.In two months.

To Josias Lambert, of Liverpool-street, in the city of London, Esquire; for an improvement in the process of making iron, applicable to the smelting of the ore, and in various subsequent stages of the process, up to the completion of the rods or bars; and also for the improvement of the quality of inferior iron. Dated March 30, 1829.-In four months.

To William Prior, of Albany Road, Camberwell, in the county of Surrey, gentleman; for certain improvements in the construction and combination of machinery for securing, supporting, and striking the top-masts and top-gallant-masts of ships, and other vessels. Dated April 11, 1829.-In six months.

To John Lihon, of Guernsey, but now residing at the Naval Club-House, Bond-street, in the county of Middlesex, a commander in our Royal Navy; for an improved method of constructing ships' pintles, for hanging the rudder. Dated April 14, 1829 -In six months.

GILL'S

TECHNOLOGICAL & MICROSCOPIC REPOSITORY.

LI.-Specification of a Patent for the Construction of a Furnace for Generating Steam by Anthracite Coal, and for the Use of various Manufactures requiring Intense Heat. Granted to BENJAMIN B. HOWELL, Philadelphia, October 14, 1828 *.

WITH FIGURES.

THE improvements claimed, consist in the form and princi ple of the interior of the furnace, and in its being in a sepa rate structure from that of the boiler, or other body to be heated; and by means of which the heat is generated without bringing the fuel into contact with the boiler or other body; and in the application of an artificial blast upon anthracite coal, and thus increasing, in a great degree, the intensity of the heat; and likewise giving it the necessary direction, through the communicating flues of the furnace, to act upon the bodies to be heated.

The drawings exhibit a front elevation, a ground plan, and a section; all made upon a scale of six feet to an inch.

The exterior shape and proportions may be varied at pleasure, provided the principles of generating and applying the heat be retained.

With a furnace of this construction, and a moderate blast, the flame and the heat may be carried to almost any required extent under the boiler of a steam-engine, or other

VOL. IV.

* From the Journal of the Franklin Institute.

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