the flat chambers-I mentioned, among several others, Furnival and Smith's patent in 1823, Dr. Alban's in 1825, James's in 1832, Hebert's 1833, not excepting Mr. Hancock's in 1827. All these were discussed without any true resemblance being found; and, as respects Mr. Hancock's, that was soon dismissed-from the notion, then entertained, that it was the kind of boiler which he used, and not that which he abandoned, as useless. By the one "used" I mean, of course, that which Mr. Hancock described himself as using in your 534th Number, pages 67 and 69; and that boiler, I am sure, every mechanic will acknowledge to be the very antipodes of Sir James Anderson's in its entire construction, arrangement, and action. Sir James's water-chambers are flat, like Salisbury Plains,-Mr. Hancock's (in proportion) more mountainous than the Alps; Sir James's are independent of each other,Mr. Hancock's dependent; Sir James's are individually so strong that they are proof against the highest pressure of steam that it is possible to generate in them,-Mr. Hancock's individually so weak as to be useless, unless combined together for mutual support, and even then are very unsafe, as experience, indeed, has most lamentably proved—while Sir James's, were they to burst, could, obviously, do no harm whatever. could pursue the comparison to a dozen other material points, and show much greater differences; but, as those already instanced show the impossibility of identity, either in construction or arrangement, I shall for the present quit this part of the subject.

I

I have now to entreat the attention of the reader to a few remarks on the subject of the patent taken out in the year 1827, which gave to Mr. Hancock the exclusive right, according to his assertion, of using flat chambers for the generation of steam. The specification of the patent referred to is enrolled in the Petty-bag Office, Chancery-lane,-I have just been there to read it, and found, that the real claim therein made was not to every kind of flat chambers, but to the particular construction of those described. Could Mr. Hancock be ignorant of this fact? Did he make the unqualified assertion to impose upon your readers that he was the first person to use flat chambers of any kind? Has

Mr. Hancock calmly reflected upon all the consequences of making such unfounded statements in the widely-circulated pages of the Mechanics' Magazine, for the obvious purpose of injuring an honourable competitor? Is not this conduct exactly in keeping with placarding his steam " gig" with the words "No connection with the Steam Carriage and Waggon Company?" thus servilely copying the miserable expedient of the lowest tradesman, "no connection with the next shop," in order to throw odium upon his respectable neighbour. Does this practice of Mr. Hancock's accord with his preaching, when he deprecates in moving terms, applied to another, the very conduct he is pursuing himself? "Let every one, (says he,) in so noble a race, bring for himself the resources of his own talent only, and make it a point scrupulously and honourably to stand clear of the discoveries and combinations wrought out by his competitors," &c.; and, in the same breath, Mr. Hancock accuses others of pirating from him the very thing which he virtually acknowledges, in his specification, never belonged to him! It is evident, that Mr. Hancock knew of prior patents to his own, wherein flat chambers were used, without even being claimed as new at the time, (which they were not, as I saw them in use eighteen years ago,) and therefore prudently kept the broad claim out of his specification-wherein unfounded pretensions would be fatal.

Mr. Hancock likewise endeavours to depreciate the labours of Sir James Anderson, by pretending that the Baronet had not had a twentieth part of his experience. On this point I think it fair to observe, that the experience of these gentlemen commenced within a year of each other, and that the boast, on the part of Mr. Hancock, is rather ill-timed when he makes allusion to his patent of 1827-the contrivances in which are of such a character, as to render the new construction almost impracticable, and, when made, incompetent to remain steamtight for an hour, in actual practice.

In stating these and other facts, in defence of an absent person, it is far from my wish to detract from the real merits of Mr. Hancock, who, apart from these untoward proceedings, to which he has been instigated, I regard as a man of genuine talent and respectability.

It has been a rule with me never to answer an anonymous letter, but the classic pen of the reverend gentleman who signs himself "An Amateur Mechanic," is as well known to me as if he had appeared in his proper person. He states, that Sir James Anderson's boiler "differs from Mr. Hancock's only in two points-the steam chest or separator, and the direction given to the heat." Well, though that is obviously incorrect, it is quite enough; for I am quite ready to leave the question to the readers of the Mechanics' Magazine, whether the situation of the steam-chest, and the manner of producing the steam, are trifling matters or not, in the construction of steam generators?

I am, Mr. Editor,
Yours respectfully,
L. HEBERT.

Camden Town, 11th August, 1838.

MR. HANCOCK'S AND SIR JAMES ANDERSON'S FLAT-CHAMBERED BOILER.

Sir, I am exceedingly sorry to see the mistake which has been made in copying the name of the patentee mentioned in my letter of the 31st of July-which should have been J. C. C. Raddatz, who, in his patent method of generating steam, uses flat chambers placed vertically, side by side, over the fire-place, with spaces between each chamber, as described in my letter to you-in which letter, I do assure you, I had no wish to do any more than to show, that Mr. Hancock had no exclusive legal right to flat-chamber boilers, nor to the mode of strengthening or arranging them. I only cited Mr. Smith's patent to show, that flat chambers, strengthened by bolts, had been used and patented before the date of Mr. Hancock's patent-Mr. Smith's previous patent being for one chamber so strengthened; and I cited Mr. Raddatz's patent to show, that he not only used flat chambers for his steam-boiler, but had arranged them side by side vertically, with spaces between, and fireplace underneath-which said arrangements Mr. Hancock claims in his patent two years afterwards. Besides, Mr. Hancock not having used his patent for eleven years it would be invalidated on account of non-utility, and non-fulfil

ment of the stipulations,* even though its principles had not been previously patented or used by others. Nor can his subsequent patent give him any such privileges, it being specified, I believe, as improvements on his former patent, which is nil. This latter important fact, and part of my letter to you has been omitted I trust in mistake; but, after such an open uncalled-for attack on Sir James Anderson's claims to his patent boiler, I trust you will omit nothing that may be necessary for his complete justifica

tion.

*Our correspondent is in error in stating that a patent becomes forfeited by not being put in operation. There is no "stipulation" to work the invention in a patent-grant; and, in fact, it is not an unfrequent circumstance for a manufacturer to patent an invention which might interfere with an established business, for the sole purpose of preventing its being worked, and to keep it out of the market. In all foreign countries there is a proviso in the grant, that the invention is to become public property if not put into operation within a certain time, usually two years, but not so in Great Britain. The remark, however, is not at all applicable in the present instance. Has "A Shareholder" been asleep these twelve years past? or did his steamcarriage experience commence with taking shares in the Steam Carriage and Waggon Company? Mr. Hancock has been constantly, from a considerable time previous to the date of his patent to the present day, (as appears from a "Narrative" of his steam carriage labours we have just received) using, both experimentally and practically, privately and publicly, his flat-chambered boiler, modified in various ways, but always preserving its principal distinctive features. The question of the sufficiency of Mr. Hancock's, or any specification, is one which could not be discussed in our pages, except at a great sacrifice of space, which the mechanical character of the age will enable us to occupy to better purpose. The remarks in this note apply equally to some parts of Mr. Hebert's letter.-Ed. M. M.

although only printed on one side. This curious people use a thin smooth paper, which being printed on one side, is doubled together to form a leaf, the fold forming the fore-edge of the book, which is knocked up very true, and after being stitched through, is cut at the back. In the extract from Mr. Medhurst's work, given at page 292, it is stated that “after the copies are struck off, the next business is to fold the pages exactly in the middle; to collate, adjust, stitch, cut and sew

them. I have seen a considerable number of Chinese books at different times, but never met with one yet that did not contain two pages per leaf by means of the doubled form; some thin paper writing books are put up with doubled leaves in the same manner, but when a thick paper is employed they are made up singly like our own.

The extreme care which the Chinese book-binder bestows in adjusting his folded leaves, gives an evenness to the fore-edge, fully equal to that which we obtain by means of the cutting-plough, but in respect of his sewing, Mr. Chinaman might take a lesson from the "barbarian eye" with great advantage. I remain, Sir, Yours respectfully, WM. BADDELEY.

London, August 13, 1838.

STEAM COMMUNICATION WITH INDIA.

Now that the homeward passage from India by the Red Sea has become so popular, it has been judged necessary to make better arrangements than have hitherto existed for crossing the Isthmus of Suez. When the improvements are fully carried into effect, it is expected that the whole journey will be accomplished in twenty-four hours, and the requisite steps have been taken for establishing a regular house of entertainment half-way across the desert, where the travellers are to stop and dine like stage-coach passengers in England, the principal of a respectable hotel at Cairo-an Englishman-having entered into a contract for that purpose. The last passage out was effected in only forty-three days, but there is unfortunately too much probalility of the regularity of the steam communication being interrupted, in consequence of the impending rupture

with Persia, to which country the Semiramis steamer, which was to have composed part of the line. has been ordered, with a fleet of sailing vessels. This, however, would have interfered much more seriously with the Euphrates line, if that had been adopted.

SPEED ON RAILWAYS.

[From the Monthly Chronicle.]

Among the many benefits which the human race has derived from the combination of the discoveries of science and the resources of art, the facility and rapidity of intercommunication between distant centres of population and industry by the application of steam power on railways, stands out in prominent relief.

This great advance in the art of transport over land was sudden and unforseen,-unlike other improvements, which proceed gradually to perfection through a series of partial failures. A speed was attained in the earliest trials which produced unqualified astonishment in all who witnessed it, not excepting the engineers themselves. How much these first results transcended previous expectations, and how small a part of them can be fairly ascribed to contrivance or design, may be judged by comparing them with the reports and estimates previously furnished to the railway company by engineers most experienced in this application of the steam engine.

Mr. J. Walker, the present president of the Institution of Civil Engineers, and Mr. J. U. Rastrick, one of the soundest men of practical science in the profession, made a report before the opening of the Liverpool and Manchester Railway, in which they estimated the speed of locomotive engines at ten miles an hour, and the loads they would carry at twenty tons gross. Mr. R. Stephenson, engineer of the Birmingham Railway, and Mr. J. Locke, engineer of the Grand Junction Railway, also furnished a report, in which they assigned twelve miles an hour as the speed, and thirty tons gross as the load, of a locomotive engine. In the first performances a speed of more than thirty miles an hour was obtained, and not long afterwards we witnessed a single engine drag the enormous load of two hundred and forty tons gross, at a speed of sixteen miles an hour on some parts of the line, and at an average rate of twelve miles an hour from terminus to terminus.

These early performances have hitherto not been much exceeded, when load and speed are considered; but cases have occured with engines travelling either unloaded or

drawing a less than usual weight, in which much greater speed has been attained. We have ourselves witnessed a velocity of above forty miles an hour with a considerable load, and nearly sixty miles an hour with an unloaded engine.

For various reasons, however, the full power of speed of the locomotive engine has not yet been devoloped. It is evident that ⚫ on short lines of railway, especially when it is necessary to stop at various intermediate stations, very considerable average speed cannot be obtained. On approaching each station the action of the impelling power must be suspended, and the train of carriages allowed to come to rest by a gradually declining motion. The sudden stopping of the rapid progressive motion of a heavy mass would be attended with the destruction of the carriages and machinery; and even the common brakes provided to bring the train to rest should be sparingly used, as they are always attended with more or less injury. It must also be considered, that any delay at a station produces a greater diminution of the average rate of motion when great speed is attained than with a slower rate of traveliing. If in a trip of thirty miles a speed of thirty miles an hour be the rate when actually in motion, and the stoppages at the stations, and delay in coming to rest and getting up the speed, amount to fifteen minutes, the average speed will be reduced to twenty-four miles an hour; the loss of speed being six miles an hour, or one fifth of the regular rate. If in the same trip a speed of ten miles an hour be the rate when in motion, and the same delay of fifteen minutes be produced at the stations, the average speed will be reduced to about nine miles and a quarter an hour; the loss of speed being only three quarters of a mile per hour, or about one thirteenth of the actual speed when in motion.

To develop, therefore, to their full extent, the actual powers of speed of railways worked by steam engines, we must wait for the completion of some of the great lines of communication now in progress of construction between the metropolis and the more distant points of commercial intercourse, and for the complete organisation of the traffic and intercourse upon them. When that is accomplished arrangements will doubtless be made for despatch trains, which will communicate between the termini of the longest lines, without any intermediate stoppage. The only indispensable cause of stoppage, at present, is to take in water and fuel. Now the consumption of both of these is in the direct proportion of the amount of the load carried. If we can now transport a gross load of fifty tons thirty miles without a

relay of water and fuel, we could transport twenty-five tons twice that distance, or sixty miles, without any relay. But, independently of this, nothing can be more easy than to provide, if desirable, tenders sufficiently capacious to carry the quantity of water and fuel which would be required for the transport of a light despatch train from terminus to terminus of any line of railway now projected.

Seeing the vast amount of national capital which has been, and is about to be, absorbed by these enterprises, and the large portion of all classes of persons in this country whose well-being will be directly and indirectly affected by them, we feel assured that we shall not be regarded as performing an unacceptable duty in attempting to unfold, in familiar language, the means whereby those great improvements are likely to be effected, and to investigate the probable extent to which they may be carried.

The impelling power of the steam is applied, in the first instance, to drive a piston backwards and forwards in a cylinder, which rests in an horizontal position on the axle of one pair of the wheels which support the engine. The rod of this piston is attached by a joint to a bar which lays hold of an arm, called a crank, placed on the axle of another pair of the engine-wheels, called the driving or impelling wheels. As the piston is driven through the cylinder in each direction, this arm is made to revolve by the bar which the piston rod moves, Now, the arm being fixed on the axle of the driving wheels so as, in fact, to be part of that axle, when it is made to revolve the axle must revolve with it. If the wheels were placed on this axle, like the wheels of common road carriages, the effect of this operation would be merely to cause the axle to revolve within the naves or boxes of the wheels, and the engine with its load would stand still. But, on the contrary, the wheels of the engine are firmly keyed upon the axle so as to form one solid piece with it. The axle, therefore, cannot revolve without compelling the wheels to revolve with it.

Now if one pair of the wheels which support the engine be in this manner compelled to turn round, either of two things will happen: the engine will advance along the road, the tires of the wheels rolling on the surface; or the engine will stand still, the tires of the wheels rubbing on the surface of the road. So long, however, as the resistance which holds the engine back is less in amount than the resistance which the pressure of the tire on the road produces to the rubbing motion, so long will the engine advance and the wheels roll. It is found, in practice, that, on a level railway, a load amounting to more than twenty times the amount of the pres

sure on the wheels will be insufficient to stop the progressive motion of the engine, when the axle of the wheels is made to revolve by the steam power.

Each motion of the piston, backwards and forwards in the cylinder, causes one revolu tion of the arm driven by the piston rod, and, therefore, one revolution of the driving wheels of the engine, This produces a pro gressive motion of the train through a distance equal to the circumference of the driving wheels. In accomplishing this, the cylinder must then be twice filled with steam by the boiler, and, therefore, to propel the train through a distance equal to the driving wheels consumes a measure of steam equal to twice the capacity of the cylinder.

But in the successive attitudes into which the revolving arm is thrown, the power of the piston-rod upon it is subject to great variation. When the elbow forms a right angle the power acts with its full effect; and according as the angle of the elbow becomes more extended and obtuse on the one hand, or more contracted and acute on the other, the effect of the power is diminished, and this diminution is continued until in one extreme position the arm is stretched directly against the end of the piston-rod, and in the other it is doubled down upon it. In both of these extreme positions the piston loses all power over the revolving arm, and therefore, for the moment, its influence in impelling the engine and train is suspended. This happens twice in every revolution of the arm.

Under such circumstances it is evident that the train would be impelled with an unequal motion, being urged by starts. Besides this, if, by chance, the train should come to rest when the arm is in one of those attitudes in which the piston has no power over it, no motion could be produced by the engine, and to put it in motion it would be necessary to push the train by some external force until the revolving arm should alter its position.

To avoid this inconvenience a second cylinder and piston are provided to drive a second arm, placed on the same axle as the first, but fixed upon it so as to be always in a position at right angles to the first. Thus, when the first is horizontal, the second is vertical, and vice versa. By this arrangement an impelling power is obtained which is very nearly uniform in its action. By the relative position of the two arms it will be seen that, at the moment when one is in the attitude in which the piston loses all power over it, the other is in the plentitude of its energy; and according as the efficiency of the latter is diminished, that of the former is increased. By this means the sum of the

effects of the two pistons on their respective arms is very nearly of an invariable amount. Nor is any power lost by this expedient, since the combined effect of the two pistons will be equal to that of a single piston of twice the magnitude of either, and which in each stroke would consume twice the quantity of steam. The measure of steam, therefore, necessary to draw the train through a distance equal to the circumference of the driving wheels will be four times the capacity of either cylinder.

When these preliminary principles are understood, the circumstances which determine the speed of the progressive motion will be easily comprehended. In the engines which have been generally used for several years on the Liverpool and Manchester Railway, the impelling wheels have been five feet in diameter. The circumference is then 15.7 feet. Each stroke of the piston then impels the train over 15.7 feet, and ten strokes carry it the distance of 157 feet. The number of strokes necessary to carry the train a mile will therefore be 336. It is a matter, then, of easy calculation to show, that if the piston make 168 strokes per minute, the train will move at the rate of 2640 feet per minute, which is equal to thirty miles an hour.

Assuming for the present that steam can be produced by the boiler with sufficient rapidity to supply the cylinders, let us inquire what are the circumstances which place practical limits on the further increase of speed. The very rapid reciprocating motion of the pistons, and of every part of the working gear and machinery connected with them, is attended with much concussion and vibration, and is certainly one of the most formidable sources of wear and tear, and therefore of expense, in the locomotive engine. While the mechanical connection at present used between the pistons and the driving wheels is retained, it is evident that there is only one method of obtaining increased speed without increasing the rapidity of this vibration of the pistons; and that method is by increasing the diameter of the impelling wheels. If, instead of being five feet in diameter, the impelling wheels had diameters of ten feet, each revolution would carry the train through twice the distance; so that with the same number of strokes per minute of the piston, the actual speed of the motion would be doubled. Either of two advantages would thus be placed at the option of the engineer increased velocity without increased vibration, or the same velocity with greatly diminished vibration.

Why then, it may be asked, has not this very obvious expedient been long since resorted to ? To answer this, we must bring