1819.1 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



290 



1,128 cubic feet; and the greatest leakage that can arise from an 

 injury of the cylinder cannot let it down so rapidly as to cause any 

 damage. The load is supported by an air cushion during the 

 whole time of its ascent, instead of depending on chains or racks, 

 which prevents any risk of its falling. The complete control over 

 the motion of the platform that is given by the air-valve which 

 regulates the entrance and exit of the air, gives the means of 

 checking, stopping, or reversing the motion at any part of the 

 stroke; and it prevents any concussion at the ends of the stroke, 

 although the lift has a quick action, and is stopped dead at each 

 end of the stroke at the exact leveUrequired. The friction of the 

 lift is very small, as the cylinder works through a water joint; and 

 in consequence of the low pressure at which it is worked the loss 

 at any leak is very small, and the strain upon the joints is much 

 diminished. 



This pneumatic lift is of course applied most economically and 

 conveniently in the case of blast-furnaces, where the compressed 

 air can be obtained very economically and without additional ma- 

 chinery; but it is pi-obable that its application may be extended 

 advantageously to several other cases, such as raising railway 

 wagons, or even railway trains, discharging vessels at quays, and 

 various other purposes, and it possesses several advantages which 

 make it deserving of consideration. The low pressure at which it 

 is worked causes great simplicity and economy in the construction 

 and working, the loss at leaks being reduced, and the joints easier 

 kept in order; and the friction is very small as the cylinder works 

 through a water-joint. Where the lift is not required to be always 

 working, but only to be worked at intervals, a further economy 

 could probably be eifected by employing a reservoir for the com- 

 pressed-air, to accumulate power during the time that the lift is 

 not required to work, and thus reduce the size of engine requisite 

 for the work; a large capacity of reservoir could be constructed 

 at a moderate expense, on account of the low pressure upon it. 

 It may be mentioned that at the Corbyn's Hall New Furnaces the 

 reservoir of compressed-air contains 5,000 cubic feet, at the pres- 

 sure of the blast 2^ lb. per square inch, and consists of four 

 wrought-iron cylinders from 6 to 8 feet diameter, constructed of 

 riveted plates from § to ^inch thick; and the cost would be 

 about 3/. per 100 cubic feet for air reservoii-s of this construction. 



Semarhs made at the Meeting after the reading of the foregoing Paper, 



Mr. Buckle observed that he had frequently seen this lift at the works of 

 Mr. Gibbons, and could bear testimony to its smooth and exact working 

 and its uniform motion. He was of opinion it might be usefully applied to 

 a variety of purposes, as it was undoubtedly the best description of lift that 

 he was acquainted with for its present purpose. 



Mr. Beyer said it appeared to him to be a very simple and efficient 

 mode of raising the materials. 



Mr. Cochrane observed that a similar lift was employed at his iron 

 works, for which he had been indebted to Mr. Gibbons; it had proved en- 

 tirely satisfactory, and there had never been any accident with it. 



Mr. Gibbons remarked that his object in bringing the lift before the In- 

 stitution, was to render it more generally useful j for in his opinion it might 

 be advantageously applied to a great variety of purposes, more especially at 

 railway stations and in the docks. It would be a great convenience for 

 raising and lowering trucks, and for loading or discharging vessels ; as the 

 platform could be quickly raised or lowered to any exact level, and could be 

 stopped at any point at pleasure without concussion, and held quite firm in 

 the position without any danger of falling, as long as might be required. 



Mr. Slatb thought it was applicable to lifting railway wagons; and con- 

 sidered that a small blowing engine might be advantageously employed for 

 the purpose, working at a much quicker rate than usual, even 700 feet per 

 minute, like the pistons of locomotive engines; the leakage of the pistou 

 would then be of much less consequence. 



M. CowPER suggested that steam might be available for the purpose of 

 raising the lift where there was not a blowing engine at work ; for although 

 there would be a loss of steam by condensation on the surface of the water, 

 that loss would be very small compared to the whole quantity of steam em- 

 ployed, as the surface of the water would become quickly heated by the 

 steam, but the heat would only extend very slowly downwards in the water. 



Mr. Gibbons remarked that he considered there would be a difficulty in 

 applying steam, from the difficulty of keeping the joints steam-tight. 



M. McCoNNELL referred to the use of hydraulic cranes which had been 

 introduced at some railway stations and other places ; and observed that it 

 appeared to involve the question of the relative cost and advantage of air 

 and water as the means for communicating the power. 



Mr. Gibbons observed that the pistons necessarily used in hydraulic 

 cranes were liable to get out of order, and were a source of expense and 

 trouble, and there was also considerable loss of power from friction, which 

 was not the ease in the pneumatic lift. He thought that by the latter plan 

 a whole railway train might be raised a considerable height, without the 

 motion being felt by the passengers. 



REGISTER OF NSVT FAT2NTS. 



SAWING AND CUTTING WOOD. 



Henry Francis, of Chelsea, Middlesex, engineer, for " improve- 

 ments in sau-inq and cutting wood." — Granted January 4; En- 

 rolled July 4, 18 i9. 



The improvements relate, firstly, to the construction and use of 

 saws so as to improve and facilitate their cutting wood. Saws have 

 hitherto usually consisted each of a series of teeth, and the teetli 

 of a saw have each been alike, and they have been bent in alternate 

 directions. Tlie consequence of this construction has been, that 

 the wood cut thereby has had larger or smaller saw-cuts on the 

 surfaces, according to the teeth used ; these observations apply to 

 saws generally, both straight and circular. Now according to this 

 part of the invention, the teeth are combined with cutters, and the 

 cutters are made to alternate with the teeth, so tliat a tooth follows 

 a cutter in regular succession, though this arrangement may be 

 varied. The teeth are to be of any of the ordinary constructions, 

 according to the class of saw which is to be made, and the cutters 

 preferred are " fleur teeth," that is, they are not hooked or under- 

 cut, but incline both ways, and are bent alternately on either sides, 

 as the teeth of saws have lut!)erto been bent ; but the teeth are left 

 unbent, by whicli means the cutters make a cut on eitlier side, and 

 the teeth remove the wood between the cuts. It is of great import- 

 ance that the cutters on either side should follow one another with 

 accuracy, in order that the cut made on either side may be smooth 

 and true, and that the two cuts should be parallel, — for which pur- 

 pose a file is iixed in a flat block, the tile being at one edge, and at 

 a distance below the surface of the block equal to that to wliich 

 the cutters of a saw are bent, sucli block being eight or ten inches 

 long and three or four inches wide ; by which means the projecting 

 cutters on either side are made correct, so as to follow each other 

 in the same line. The flat block when used rests on the surface of 

 the saw, and is to be moved to and fro so that the file will come 

 against the cutters, and thus the cutters be filed away at the outer 

 sides of the points till they are all sharp, and range correctly one 

 after the other. This block will also be found useful when sharp- 

 ening saws of the ordinary construction, and forms part of the 

 invention. In using these saws in saw-mills, in place of causing 

 them to move up and down vertically, or at right angles to the sur- 

 face of the wood as heretofore, a better cut may be made and with 

 less power by having the saw-gate so arranged as to move in an 

 inclined position, generally at an inclination of about 67° to the 

 surface of the wood. In cutting off thin slices of wood with the 

 impro\ed saws, it is preferred to employ a smooth metal plate or 

 table, with a transverse slit or opening, the metal on the sides of 

 the opening being formed to an inclination. The wood is moved 

 longitudinally on this plate, and the saw used (which is to be 

 straight) is inclined, so as to be parallel with tlie opening through 

 the plate, and the edge of the saw protrudes a distance (in a direc- 

 tion to meet the moving wood), according to the thickness of wood 

 to be cut off; a quick reciprocating motion is given to the saw as 

 the wood moves forward on the bed-plate, and the portion cut off 

 descends through the plate as a shaving in a plane. 



The second part of the invention relates to improvements in 

 mounting saw-gates, which are preferred to be inclined in place of 

 vertical, and consists of employing springs ; and the springs are 

 formed of such strength, tliat they will lift the saw-gate, by which 

 means the working is improved. 



The third part of the invention is applicable to the sawing of 

 wood into planks and boards from timber of irregular sides, to avoid 

 shaping the timber first before it is fixed in a mill, — and consists of 

 guiding each saw, so as to ensure the several saws stretched in a 

 saw-gate to cut parallel boards or planks, in place of depending on 

 the great tension now resorted to for preventing the saws being led 

 away by knots or inequalities of the wood. In carrying out this 

 part of the invention, a plate of wood is fixed to the irregular sur- 

 face of a log of wood, the outer surface of the fixed piece being 

 true, and moved against a guide-piece in the mill, so as to cause 

 the log to pass through the mill truly, notwithstanding the irregu- 

 larity of its sides ; and thus the boards or planks cut off will be 

 parallel, in order to ensure which a bar of hard wood is fixed across 

 the saw-mill, having slits cut in it at tlie intervals apart at wliich 

 the boards are to be cut, and this bar is so fixed that the backs of 

 the several saws shall enter the cuts and move up and down in 

 them, and are guided truly by them. 



39* 



