lines of rails. He employs a truck with wheels, without flanges, and perfectly cylindrical, and on which a platform is placed. An iron tube crosses this, terminating at each end at right angles, into which is introduced mercury; so that it is, in fact, a mercurial level. On placing this along the lines of railway, the mercury in the columns is found to go up and down; and into each is introduced a float and a piston, to the top of the rod of which a pencil is attached, which, on the occurrence of any incorrectness of the line, describes a curve on a sheet of paper, the ordinate of which gives the variation of the rail. Dr. Lardner has tried it on several parts of a line where the variation is perceptible. The instrument was checked so as to show that this curve was doubtlessly the real representation of the line; and being simple and easily applied, it would, no doubt, be found useful to contractors on new lines of rails.-Literary Gazette.

IMPROVED MACHINE FOR CUTTING RAILWAY BARS.

MR. J. GLYNN has communicated to the Institution of Civil Engineers the following means of Cutting the ends of Railway Bars square, so that they may truly abut against each other. In general, the ends, rough and ragged as they come from the rolls, are separately re-heated and cut off by the circular saw; but the accuracy in this case depends on the workman presenting the bar at right angles to the plane of the saw. As this cannot be insured, the difficulty is thus obviated: 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; they are three feet in diameter and one-eighth of an inch in thickness, with teeth of the usual size in circular saws, and make 1,000 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 being 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 78 lbs. 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.

PNEUMATIC RAILWAY.

On May 14, was made a second series of experiments with models, of Clegg's Atmospheric Principle of propelling carriages by means of exhausting a tube laid down the line of road, of the air contained in it, and creating a vacuum. The tube being exhausted by means of an air-pump, the models, the leading one having a piston which forced open the valve of the tube, proceeded at a rate of extreme velocity along the line, a distance of thirty or forty yards, the ascent being one foot in thirty; the models were heavily laden, each carrying a couple of persons, and upwards of 15 cwt. of ballast being disposed over the whole. The machinery performed to perfection and gave general satisfaction. The advantages that this system proposes, both for the public and the railroad proprietors, are very obvious - cheapness, security, speed, and no danger of explosion.- Examiner.

ADAMS'S BOW-SPRING RAILWAY CARRIAGES.

MR. ADAMS's application of Bow-springs to Railway Carriages will

be attended with the following very prominent advantages;

1. A great diminution of friction.

2. Diminution also of weight - because the elasticity of the springs, and the equable motion they produce, will admit of considerable reduction in the weight of almost any part of railway vehicles, and also in the fitting up of the locomotive engines.

3. Security of position on the rails. It has hitherto been deemed necessary to keep the axles in their positions by means of side guides; which, however, prevent them from accommodating themselves to any of the unavoidable inequalities of the railway.

4. Adaptation to all changes of circumstances. It has been found by exact measurements, that the axles of many railway carriages are not placed accurately parallel, and cannot run true on the same line; the consequences of which are, increased friction, - increased wear and tear of the rails, the wheels, and carriages, -great additional weight in every part of the carriages, to enable them to withstand the violent oscillations and concussions which even a small deviation, (at high velocities,) from true parallelism in the axles must occasion, while the power given by the Bow-springs to each wheel to accommodate itself to every ordinary inequality and impediment, is a remedy for all, or nearly all, of the evils to which reference has been made. Railway Times.

GALVANIC TELEGRAPH AT THE GREAT WESTERN RAILWAY.

THE space occupied by the case containing the machinery, (which simply stands upon a table, and can be removed at pleasure to any part of the room,) is little more than that required for a hat-box. The Telegraph is worked by merely pressing small brass keys, (similar to those on a keyed bugle,) which, acting (by means of galvanic power) upon various hands placed upon a dial-plate at the other end of the telegraphic line, point not only to each letter of the alphabet, (as each key may be struck or pressed,) but the numericals are indicated by the same means, as well as the various points, from a comma to a colon, with notes of admiration and interjection. There is likewise a cross (X) upon the dial, which indicates that when this key is struck, a mistake has been made in some part of the sentence telegraphed, and that an "erasure" is intended. There are wires communicating with each end, as far as completed, passing through a hollow iron tube, not more than an inch and a half in diameter; which is fixed about six inches above the ground, running parallel with the railway, and about two or three feet distant from it. The machinery and the mode of working it are so simple that a child who could read would (after an hour or two's instruction,) be enabled efficiently to transmit and receive information.

This telegraph is the invention of Mr. Cook and Prof. Wheatstone, of King's College. Between Drayton, Hanwell, and Paddington, it has been in operation for a year, and not the least obstruction to its working, by any of the wires failing, has yet taken place. Should this accident occur, especially when the whole line is open to Bristol, (from the wires being enclosed in a tube about an inch in diameter,) it might be expected to be difficult of repair, or to ascertain the precise point of injury throughout the 117 miles; but this apparent difficulty has been met by Mr. Cook's invention of a piece of mechanism, in a mahogany case, not more than eight inches square, by which means the precise point of injury would be indicated in an almost incredibly short space of time.

PNEUMATIC TELEGRAPH.

THE following is the description of the Pneumatic Telegraph, invented by Mr. S. Crossley; a model of which may be seen at the Polytechnic Institution.

"Atmospheric air is the conducting agent employed in the operation of the Pneumatic Telegraph.

"The air is isolated by a tube extending from one station to another; one extremity of the tube is connected with the gas-holder or other collapsing vessel, as a reservoir, to compensate for any diminution or increase of volume arising from compression or from changes in the temperature of the air in the tube, and for supplying any casual loss by leakage; the other extremity of the tube terminates with a pressure index.

" It will be evident to every one acquainted with the physical properties of atmospheric air, that if any certain degree of compression be produced and maintained in the reservoir, at one station, the same degree of compression will speedily extend to the opposite station, where it will become visible to an observer by the index.

"Thus, with ten weights, producing ten different degrees of compression, distinguished from each other numerically, and having the index, at the opposite station, marked by corresponding figures, any telegraphic numbers may be transmitted, referring in the usual way to a code of signals, which may be adapted to various purposes and to any language. The only manipulation is that of placing a weight of the required figure upon the collapsing vessel at one station, and the same figure will be represented by the index at the opposite station.

" In establishments where the telegraphic communications do not require the constant attendance of a person to observe them, and where periodical attendance is sufficient, the signals may be correctly registered on paper, by connecting with the air tube an instrument called a pressure register, invented by the projector of the Pneumatic Telegraph, which has been successfully employed in large gas-light establishments upwards of fourteen years, for registering the variations of the pressure of gas in street mains. The same instrument produces also an increased range of the index scale, by which means the chance of errors from minute divisions is obviated.

"The introduction of railways has not only created an additional use for telegraphic communications, but the important difficulty which previously existed in the expense of providing a proper line and safe foundation, is at once removed by the site of the railway itself, possessing as it does, by its police, the most ample security against injury, either to the tubes or electric wires.

"The time occupied in transmitting intelligence by the Pneumatic Telegraph will depend on the capacity of the air-tube, the degree of compression given, and the distance between the stations: but should greater despatch be required than is afforded by one air-tube, and the cost be of minor importance, several tubes may be employed, each fitted in the manner above described, so that all the figures contained in one telegraphic number may be communicated at once; and, with four tubes, 9999 different signal numbers may be communicated, referring to so many words or sentences, and these numbers may be multiplied four-fold by letters A, B, C, &c., as indices to distinguish

each series.

"There has been upwards of twenty years' experience in the transmission of gas for illumination through ugh conduit pipes of various dimensions. In several instances, the gas has been supplied at the distances of five to eight miles by low degrees of pressure. As one proof of great rapidity of motion, it has been observed, that when any sudden interruption in the supply has occurred at the works, the extinction of all the lights, over large districts, has been nearly simultaneous. Another instance of the great susceptibility of motion which frequently happens, is the flickering motion of the lights at great distances when water has accumulated in the pipes.

"The only experience in the transmission of atmospheric air through conduit tubes, which applies more particularly to this subject, may be referred to at three railway establishments; viz., Edinburgh, Liverpool, and Euston-square, London. In these establishments, air-tubes, from 14 to 2 miles in length, have been employed for the purpose of giving notice when a train of carriages is ready to be drawn up the inclined plane by the stationary engine at the summit, so that it may without delay be put in motion. This notice is communicated by blowing a current of air through the tube at the foot of the inclined plane, and sounding an organ-pipe, a whistle, or an alarm-bell, at the stationary engine. It will be satisfactory to know, that this operation has been regularly performed from two to four years without one single failure or disappointment.

"It may be farther noticed, that a trial was made with a tube of one inch in diameter, very nearly two miles in length, returning upon itself, so that both ends of the tube were brought to one place: the compression applied to one end was equal to a column of seven inches of water; and the effect on the index at the other end appeared in fifteen seconds of time.

IMPROVEMENTS IN LOCOMOTIVES.

THE following new invention, applicable to Locomotive Engines, is considered by a number of scientific men well calculated to reduce the expense, and increase the safety, of internal intercourse: -The advantages of it are: 1st, the condensing the steam after it escapes from the cylinders, and the water produced thereby returned to the boiler to be wrought over again and again; by which means the boiler is rendered more durable, being kept perfectly free of incrustation or deposit of any kind; and no stoppage is required to take in water; of course freeing the engine of the burden of carrying a supply along with it. 2nd. The air that supports the combustion of the fuel is considerably heated previous to entering the ash-pit; by which the smoke is completely consumed, although fresh coal be used in the furnace. Consequently, a great saving in the consumption of fuel is effected. A successful experiment has been made with the apparatus. The inventors are William and Andrew Symington, sons of the late William Symington, the introducer of practical steam navigation. - Edinburgh Chronicle.

SIR JAMES ANDERSON'S STEAM CARRIAGE.

A STEAM Passenger Carriage, upon Sir James Anderson's plan, has been built for "the Steam-carriage and Wagon Company," by Mr. Dawson, of Dublin. The front body, which is entered at the side in the usual way, contains more than ample space for six passengers, each having an arm-chair, and as convenient, if not better and more comfortable accommodation, than the first-class railway carriages. The back body, which is entered at the rear, is intended for ten passengers, although affording sufficient room for twelve. It is so ample in its dimensions that one may walk perfectly erect, from end to end, without incommoding the passengers at either side; it is admirably ventilated and lighted, and is to be furnished with a peculiarly constructed table. The outside passengers sit round the roof, fourteen in number; the carriage altogether containing 30 passengers. The front boot contains a cistern for water, and a space for coke or fuel for a stage of from ten to twenty miles; and there is room at different parts of the carriage for stowage of about 11⁄2 tons of luggage, if necessary.Abridged from Saunders's News Letter.

NEW PENTOGRAΡΗ.

PROF. WALLACE has exhibited to the Institution of Civil Engineers a Pentograph of a novel construction, by which drawings may be copied or reduced and etched with great facility. Mr. Macneill bore testimony to the advantages of this construction over every other which he had seen; and stated that he had been enabled to finish a plan in 3 hours, which could not have been done by an ordinary Pentograph in less than 12 hours.-Athenæum.

LARGE SHEET OF PAPER.

THERE has been lately sent from the manufactory at Colinton, a single sheet of paper, weighing 533 lbs., and measuring upwards of a mile and a half in length; the breadth being only 50 inches. Were a