plan of REVOLVING PADDLES, to avoid the defects of the fixed paddles now used.* The evidence of Charles Williams, Esq. shows that steam vessels will live on as heavy a sea as the witness ever saw in the Channel; and that the invention of the revolving paddles is exceeded in importance only by the application of steam to the propelling of vessels. These paddles, instead of being fixed as in a common wheel, revolve with a continuous motion on their own centres; the result is, that they always enter and rise out of the water with a soft easy motion, no matter what their immersions may be. The advantages of the revolving paddles are thus stated: 1st. The violent action of the paddles of common wheels in striking the water in a rough sea, which shakes and strains both the vessel and the machinery, is entirely removed by the use of revolving paddles, as they enter and rise out of the water with a peculiarly soft and easy motion. 2dly. The revolving paddles cause the engines to work as smoothly and as efficiently in rough weather as in a calm. When a vessel, with fixed paddle wheels, rolls, and the paddles become deeply and suddenly immersed in the water, the engines do not make one-half or onefourth their required number of strokes per minute; not unfrequently they are then so overloaded as to stop altogether. The paddles thus become a source of great danger, and check the vessel's way at the moment when their propelling power is most required. 3dly. When a vessel is carrying sail with a side wind, it often becomes necessary to take in the sails, and sacri fice all the advantages and speed derivable from the wind, otherwise the leeward wheel (in consequence of * See Oldham's Patent, vol. I. page 252, On Steam Navigation. 141 the vessel lying over) would be so deeply immersed as to, work to great disadvantage, and even to impede her way. This very serious inconvenience is entirely obviated by the revolving paddles, which work equally well when axle deep in the water as when the vessel is upright. 4thly. In bringing the head of the vessel about in a narrow tide-way, or when the sails are making a tack by a sudden shift of the wind, the revolving paddles afford the greatest assistance. In such cases, the paddles on one side the vessel may, instantaneously, by any ordinary seaman, and without stopping the engines, be placed edgeways to the action of the water: the entire power of the engines then acting on the other side, causes the head of the vessel instantly to come about. This is effected without the smallest violence to either the vessel or the engines. 5thly. As it is indifferent to the action of the revolving paddles how deeply they may be immersed in the water, vessels furnished with them are enabled to carry a heavier freight than if appointed with common wheels, as the latter cannot work to advantage if immersed more than twenty inches or two feet. 6thly. In case of accident to any part of the engines or boilers when at sea, the revolving paddles may be placed edgeways; and, by thus presenting no impediment in the vessel's way, she is enabled to use her sails to the greatest advantage. Should the wind be then on the beam, the paddles have an additional advantage as lee boards. 7thly. As the revolving paddles cause no loss of power in striking the water, as they enter or rise out of it, vessels appointed with them go much faster than if furnished with common wheels. 8thly. The revolving paddles do not require so large an external projection as common wheels do. When the engines are above thirty-horse power, the projection for common wheels is so great, as materially to affect the ease and safety of a vessel in a rough sea. 9thly. Vessels with revolving paddles are enabled to employ to advantage engines of a much greater power, and with commensurate speed, than if fitted with common wheels. Vessels with common fixed paddle wheels, like the post-office packet at Holyhead, when running before the wind in a gale and a heavy sea, cannot employ the full power of their engines with safety, the wheels then running two or three times round without touching the water between the trough of the sea, and then being brought up all at once, are in great danger of causing some part to give way. The use of these revolving paddles has been already adopted in the Waterloo steam vessel, plying between Dublin and Liverpool; and in the Havre de Grace, iron steam vessel, now on the Thames. We have thus given the outlines of this truly important and valuable paper. In some of our future numbers we shall most probably give some of the more mechanical details. The Tread-Mill. ALTHOUGH we are not in the number of those who think that labour itself, and more especially what has been termed hard labour, can or will effectually and completely reform the evil dispositions of the criminal (believing, as we do, that a higher and more intellectual power must be in operation before all which we desire in the refor mation of the criminal will be effected), yet as the Tread-Mill offers more humane means than have been hitherto practised in our criminal jurisprudence and management, we give place to a description of it, trusting, at the same time, that this evident amendment in prison The wood-cut exhibits a party of prisoners in the act of working one of the tread-wheels of the discipline mill invented by Mr. Cubitt, of Ipswich, and recently erected at the House of Correction for the county of Surrey, at Brixton. The view is taken from a corner of one of the ten airing yards of the prison, all of which radiate from the governor's house in the centre; so that from the window of his room he commands a complete view into all the yards. A building behind the treadwheel is the mill-house, containing the necessary machinery for grinding corn and dressing the flour; also rooms for storing it, &c. On the right side of this building a pipe passes up to the roof, on which is a large cast-iron reservoir, capable of holding some thousand gallons of water, for the use of the prison. This reservoir is filled by means of forcing pump machinery below, connected with the principal axis which works the machinery of the mill. This axis, or shaft, passes under the pavement of the several yards, and working by means of universal joints, at every turn, communicates with the tread-wheel of each class. This wheel, represented in the cut, is exactly similar to a common water-wheel; the tread-boards upon its circumference are, however, of considerable length; so as to allow sufficient standing room for a row of from ten to twenty persons upon the wheel. Their weight, the first moving power of the machine, produces the greatest effect when applied upon the circumference of the wheel at or near the level of its axle. To secure, therefore, this mechanical advantage, a screen of boards is fixed up, in an inclined position, above the wheel, in order to prevent the prisoners from climbing or stepping up higher than the level required. A hand-rail is seen fixed upon this screen, by holding which they retain 4 |