of railroads; but from the want of strength in its construction, it seems at present suitable only to an alluvial soil. A force of steam of from two to three horse power is required to work it; it clears a space eight feet (2m. 50) wide, and 2 ft. 3 in. (0m. 70) deep, and advances 1 ft. 3 in. (0m. 38) a minute. Thus, in twenty-four hours it completes 1800 feet (547m. 20) in length; having cleared out 3250 feet (1000 cubic metres) of earth, which is levelled as regularly on each bank as it could be done by the hands of man. The expense in twenty-four hours cannot exceed 40 francs. The clearing of a cubic metre of earth, therefore, costs abouts 4 centimes. If we compare this with the price usually paid, the advantage of the invention is evident; but this is nothing in comparison with the advantages which we may expect to derive from the great saving of manual labour, and from the rapid increase of works so beneficial to the industry of the country. The inventor's first idea was to employ men in levelling all occasional elevations beyond fifteen inches (0m. 40), but it was found less expensive to employ the machine used in cutting railrods. His plan proceeds on the same principle. The same frame which carries the locomotive, is arranged so that tools, attached to it, can work upwards from the surface of the earth, instead of downwards, and thus remove these elevations. A space is levelled equal in width to the working of the locomotive excavator, and then rails are laid down to preserve the direction and the level. The locomotive follows, excavating and throwing out the earth either on one or both of the banks, and forming an inclined plane, on each side, of forty-five degrees. If a canal is required to be sixteen feet (five metres) deep, or deeper, and cannot be excavated at once, there is attached to the machine behind, an axletree, and cast-iron wheels with large felloes, by which means, as fast as the first cutting is finished, lines are traced on which to place the rails for the second, and so as to preserve the original level. A machine capable of working twenty feet wide, and eight feet deep, excavates sixteen cubic feet of earth in a minute. In railroads, the process would be nearly the same as in canals, except that the inclined plane on the sides need be only of fifteen degrees, and the earth might be carried away by carts wherever is was wanted. This machine is calculated for light and sandy soils; and is so constructed, that, should it encounter any obstacle, it may be stopped in a moment to prevent accidents. Thus, any rocky substance, if small, can be lifted up; it large, can be broken to pieces by the workmen, and carried away on the frame of the machine, after removing the tools, which can then be replaced, and the work continued. It would be difficult to give a more particular detail without the aid of the plan, which the inventor has transmitted to the academy for the use of the committee, who, as well as ourselves, have seen the machine at work. Whatever their decision may be, it seems to us that the only question now, is the application of steam to the excavation of canals and railroads. The employment of this machine on a large scale, must be attended with great advantages, whether we consider the difficulty of collecting a considerable number of workmen on one spot, the increased rapidity of the work, or the improved salubrity of low grounds by the draining of marshes, and the removal of miasma and its consequent diseases. And these great advantages, if the machine of M. Gervais can really be employed on a large scale, are to be obtained at a remarkably small expense. Taking the model, which we have seen at work, as our data, if we calculate on a three horse power steam-engine, and a consumption of 15 kilogrammes (30 lbs.) of coal per hour, we shall find, after deducting 30 per cent. interest for the outlay, and making every allowance for repairs, and loss of time when the machine is not at work, that it can excavate 957 cubic metres of earth at a cost of 48 francs 50 cents; whereas we now pay for excavating the same quantity, 478 francs 50 cents. In short, the invention of M. Gervais bids fair to make a great revolution in the mode of excavation, and we look forward with a degree of impatience for the decision of the committee of the academy.-Inventors' Advocate. Mining Rev. Description of a Machine called a Floating Clough. By GEORGE ELLIS, Grad. Inst. C. E. The machine here described is used for scouring a channel which leads from the Winestead Drainage and Haven of Pattrington, into the river Humber. It is constructed in the following manner:-The frame is made of timbers six inches by four, twelve feet long, nine wide, and six deep. This frame is covered with planking two inches thick, and through the middle of it a culvert is formed with planks, two feet six inches in width, with a small lifting door at one end. Connected with the bottom and projecting in front are two long beams called feelers, which keep the machine in its course, and in the front are frames of wood shod with rough iron like the teeth of a saw, and these are connected with racks which can be raised by a lever. At each side of the machine there is a wing which is made to fit the slope of the banks, to dress the mud from the sides, and to keep up the water behind the machine. At high tide the machine is moored in the middle of the channel, the wings are extended and kept so by ropes, and when the tide is at half ebb the plugs are taken out, and the water rises about two feet in the machine, which causes it to sink; the plugs are replaced, and thus it remains till full ebb, when the iron-shod frames are let down in front, and the tide forces the whole machine, which is like a great dam, gently down the stream, scraping with it all the mud down to the river, where it is emptied, and floated back with the return tide. The whole distance, about three miles, is performed in two hours. A machine of the same kind is used with great advantage at Great Grimsby. Proceed. Inst. Civil Eng. Description of a Sawing Machine for cutting off Railway Bars. By JOSEPH GLYNN, M. Inst. C. E. The advantage of having the ends of the railway bars cut as nearly square as possible, that they may truly abut against each other, is so great, that many attempts have been made to effect it. The author in this communication describes the method which is adopted at the Butterly Works in the manufacture of the rails for the Midland Counties Railway. In general the ends, rough and ragged as they come from the rolls, are separately reheated and cut off by the circular saw, but the accuracy in this case depends on the workmen presenting the bar at right angles to the plane of the saw. As this cannot be insured, the difficulty may be obviated as follows. The axis of the saws and the bed of the machine, which is exactly like that of a slide lathe, are placed at right angles with the line of the rolls in which the rails are made; the saws are fixed in headstocks and slide upon the bed, so as to adjust them for cutting the rails to the exact length, and are three feet in diameter and one-eighth of an inch thick, with teeth of the usual size in circular saws for wood, and make one thousand revolutions per minute; the teeth are in contact with the hot iron too short a period to receive any damage, but to prevent all risk the lower edge of the saw dips in a cup of water. The saw plate is secured between two discs of cast iron faced with copper and exposed only at the part necessary for cutting through the rail. The rail on leaving the rolls is hastily straightened with wooden mallets on a cast-iron plate, on which it lies right for sawing and sufficiently hot; thus a considerable saving of time, labour, and heat, is effected. The rail is brought into contact at the same time with the two saws, and both ends are cut off by one operation. If the saws be sharp and the iron hot, the seventy eight pound rails are cut through in twelve seconds. The rail on leaving the saws is placed in a groove planed in a thick cast-iron plate; thus all warping is prevented. The author then describes certain mechanical arrangements, which are exhibited in detail in the drawing accompanying the communication. Ibid. On Framing Lock Gates without Iron Work. By S. BALLARD, A. Inst. C. E. The ledges, or horizontal pieces, are held to the back and mitre post by dovetail tenons and wedges; thus avoiding the use of iron T pieces and screw pins, which occasion the wood in immediate contact with them to decay, while the parts not pierced with iron are perfectly sound. This method was adopted in some gates on the Herefordshire and Gloucestershire canal, and after some years' experience, is found completely successful. Tar and white lead are put into the mortices, and the wedge driven down upon it, so that every crevice is filled, and the joints rendered water-tight; the planks, also, are fastened on with oak pins instead of nails. Some discussion took place on the general opinion, that when dissimilar substances are in contact, as when a gate of one kind of wood is fastened with pins of another wood, some action tending to loosen the pins prematurely takes place betwixt them. Ibid. |