the plans for stiffening and strengthening this vessel, resemble the American river steamers, very many of which nearly approach it in the dimensions of length and beam, and one of which is believed to be about 30 feet longer and 4 feet wider. Some vessels on the Rhone are 100 feet longer than this troop steamer, but not so wide. The draught of water, however, both of the larger American and Rhone boats, is seldom so little as four feet, or double that of Mr. Winter's design. The cabins of the American boats frequently rise from 40 to 50 feet above the maindeck, whereas those of the Indus troop steamer do not exceed 15 feet; so that, although the hold on the water due to the two-feet draught is less than that of the American boats which have so long and successfully navigated the Hudson and the Mississippi, the troop steamer has proportionately less top-hamper. The vessel was tried up and down on the measured miles in Long-reach and Gravesend-reach, the average speed attained being 12 statute miles per hour; the prevalent opinion of the many competent authorities acquainted with the requirements of the Indian service being, that this first Government troop steamer for the navigation of the Indus would effectively fulfil her intended object.

ing to circumstances, the hooks bent in the form of an S are preferred.

The plates or scales B are made by preference out of boiler-plate iron by sheering and punching. If it is found necessary-particularly for light ground-to make the harrow as light as possible, besides diminishing the thickness of the hooks, the plates can be made either of thinner plateiron or may be punched out in the centre so that they will form a frame to which the tines are riveted.

Another advantage is in some cases obtained by gradually decreasing the weight in each row of the harrow, so that the first row next the crossbar Cis made the heaviest, and each following row lighter, which can be effected by punching a centre-piece out of the plates, or by gradually diminishing the thickness of the plates, hooks, and tines, and likewise by gradually shortening

the tines in the last two rows.

Correspondence.

RIFLED CAST-IRON SERVICE GUNS. TO THE EDITORS OF THE "MECHANICS' MAGAZINE." GENTLEMEN,-Your correspondent "W," in your last number, might have been content to scoff at my plan for converting our existing service guns into rifled guns, without at the same time calling my logic in question. Have I unwittingly done him any injury by publishing the results of my experiments? which you unguardedly admitted into your columns It is really cruel of him to say of the statement "You have not, gentlemen, accustomed your readers to such logic as this, and few indeed will receive it." I am pained.

I might be well content to leave this letter of "W's." to be its own most clear refutation; but as reckless assertion may sometimes mislead, I think it better to point out a few of the eccentricities of your correspondent's notions.

66

He is indignant at my venturing to call my converted service guns good rifled guns." I never said that they were the best that could be made for

To remove the harrow from the wheels, it is first unhooked from the axletree D and cross-bar E, then the side-stays E of the frame and steering-wheels G are removed and the harrow falls down ready for use.

all kinds of service. But still I must adhere to the belief that the guns when altered as I have proposed will be a wise policy to improve them in the manner I have shown to be practicable, rather than allo them to remain in their present less efficient state. Your correspondent's objection is curious. He says:-"At 2,000 yards, indeed, Mr. Britten's guns are more effective than the smooth-bored guns, and at distances between 3,000 and 6,000 yards they continue to possess destructive power, whereas the smooth-bore are useless; but this does not compensate for want of power at shorter distances." What does this mean? My despised system enables our old guns to throw shells fifty per cent. heavier than the common solid shot twice as far with effect; but yet, at shorter distances, they have want of power!! May I beg for an explanation? It appears that my guns are not good rifled guns, because I only venture to use "ridiculously small" charges of powder. It is not the work done, then, but the powder ment. "W." complains of what I have done because I do it easily.. I have shown to what extent our guns may be improved by spending twenty shillings upon each. My opponent rises up in anger because he wishes thirty pounds spent on every gun. He does not condescend to tell us how much more he can do for thirty pounds than I do for twenty shillings. He does say that in France a large number of 30-pounder guns have been converted into 52-pounders on the more expensive plan, and are fired with heavier charges than I use, but he does not venture to give us any facts to enable us to judge how much better these guns are than mine. One steam-vessel could hardly be said to be decidedly better than another simply because she consumes more fuel.

short range firing, because they combine the short sharp hitting of the light round shot with the harder hitting of the heavy shells when the round shot cease to be effective.

With regard to hooping guns with wrought iron, I have no desire to interfere with those who advocate this mode of strengthening guns. If they can so add to their strength so much the better for me if my plan should be adopted.

A patent for doing this has been taken out by Capt. Blakely, and with several guns which that gentleman has experimented with at Liverpool some important facts have been obtained. I cordially wish has applied my system to his guns; I have supplied that gentleman every success with his patent. Ho him with the projectiles he has used; I have for several years past afforded him the benefit of the experience I have gained, and furnished him with the details of my invention, which he has freely used. Still I contend that hoops are not indispensable, and my experiments prove this. They may, however, be useful, and if so let them be used; but let not those who want to use them attack me in the dark and try to injure me without a cause. Your obedient servant,

BOOBLEY BRITTEN.

THE ARMSTRONG BREECH. GENTLEMEN,-If the "Armstrong" principle be defective for large guns, I fear that your correspon dent "F." has not hit on the cause of failure.

There does not appear to be any reason why, if the different parts of large guns can be made of strength proportioned to the strain which their heavier duty produces, they should not resist the shock, and it is probable that the difficulties attendant on this increased demand on mechanical skill will necessitate a different method of construction of these guns as to some of their details.

BOX BOATS.

MR. C. M. MEARS proposes the following means of releasing paddle-box boats easily:Each boat is placed in the usual position, viz. keel upwards, and lays on an iron frame work, the outside of which is connected with the ship's side, by means of a hinge on the inner side; two racks are fastened one at each end, so that by turning two small cog wheels (one for each rack) the inner side of the boat will be hove up to an angle of about 25 or 3) degs. Upon the frame two slides work, one for the after part of the boat to lay upon, and another for the fore part, so that when the boat reaches the above-mentioned angle, it is launched bodily down the length of the slides. In the middle of these slides there is a joint with a catch on the outer end, which just catches on the outer moulding of the boat, so that on the boat sliding off the paddle-box the joint causes the outer part of the slides to drop, and the catch drawing the outer side of the boat inwards causes her to fall fairly in the water; a long and stout painter having been of course first made fast to the boat, and there being a hand to attend it, the boat being allowed to drop astern ready to be hauled up when required.

This invention is only intended for a case of emergency such as Iire, &c., &c., when two men at a minute's notice may throw the largest boat in the water, perfectly clear of the paddle-box or ship's side, and then hauled to the most convenient place for manning and t king in her complement of passengers.

As re

ACCLIMATIZATION OF THE CHINESE BAMBOO IN CENTRAL FRANCE.-In China, a species of bamboo grows so far towards the north that the French Societé d'Acclimatization imagined it might be capable of naturalization in France. The experiment has been tried, and seemingly with success. gards the Chameerop Execlsa, or Palm of Northern China, it has also been tried in France, and with perfect success. Indeed, there could have been little doubt as to the result, seeing that specimens of the same palm flourish quite well in Kew Gardens for the most part without protection.

When I ventured to point out what could be done could be done if expense needed no consideration. for twenty shillings, I did not say that nothing more

One thing your correspondent certainly should have hesitated to state,because it is spiteful and untrue. The anonymous "W." goes so far as to say that "unfortunately it is too well known that Mr. Britten's guns have totally failed at all fighting distances-that is to say, at all distances under a mile." How does he learn this? He merely assumes it from the fact of my using small charges. Now, although I only think proper to employ from my unstrengthened cast-iron service guns a charge of one-tenth of the weight of projectile, while for the Armstrong gun the charge is one-eighth, it is a fact that my guns have length of range equal to the Armstrong gun up to the serviceable elevation of 5°, and it is also true that the velocity of my shells, notwithstanding their great size, is, for about 3,000 yards, as nearly as possible the same as the Armstrong shells. The time of flight of the Armstrong shell for 3,000 yards is 11 seconds, and the time for mine in a flight of 3,300 yards is eleven seconds and six-tenths. Will "W." venture to say that the Armstrong gun is not a good rifled gun because of this defect? There is another point. It is well known that the common round shot fired with the usual heavy service charges has, for the first few hundred yards, a higher velocity than any elongated rifle shot yet fired. For some purposes this high velocity might prove of great use in service. On such occasions the round shot could be fired from my rifled service guns as well as if they had a smooth bore. The grooves would not interfere with the shot, nor would the shot hurt the grooves. I commend these facts to "W." Perhaps he will now see that the rifled service guns are peculiarly well adapted for

One great point, I conceive, in the manufacture of rifled ordnance is, that the pieces should be made as light as possible. There must be a certain quantity of metal for strength, and also to prevent excessive recoil, but the inertia which secures the latter On the contrary, it renders it more liable to be burst by the greater effort it imposes on the gun to resist the explosions, or rather to aid this force in ejecting the ball. I need go no further for an example than the experiment proposed by F. of firing a bullet at a penny piece. If it were not for the inertia of the piece, the hole would not be torn in it. If it had no weight the bullet would carry it along with it or turn it aside. I may remark, however, that this is an instance of impact, and is not a parallel case to the explosive force of gunpowder, which though excessively rapid is not instantaneous in action, accumulating in a highly increasing ratio to the time, and not, as "F." observes, in a ratio proportional to the time. Without further commenting on many debatable points, I will make a few remarks on the principle by which "F." arrives at his conclusions. It is this: When bodies of different weights, e.g., a cannon-ball and the breech of the Armstrong gun, are acted on by an explosive force, the heavier does not begin to move till the lighter one is in motion (I use the terms heavy and light because "F." does so, the weight has nothing to do with causing inertia). Now this idea is quite erroneous. Inertia does not present so stubborn a front to force as to prevent a body from moving at its gentlest bidding. Each of these supposed bodies would, if free, begin to move at the same instant, i.e., as soon as the first pressure of the explosive force is exerted. In the case of the ball there is no obstacle, but its inertia is being overcome or its momentum being increased up to the time of its leaving the muzzle. In the case of the other body, the breech, it would also, whatever its comparative weight, move with a contemporaneous velocity varying with its weight, were it not that it is in contact with the screw behind it, which contact imposed upon it the same motion as if it were a portion of a solid gun rigidly attached to it in the same position as that it has been supposed to occupy.

The great weight of a gun produces friction of the wheel, &c., and this being a species of resistance which requires a certain amount of force to overcome it, the gun does not probably begin to recoil so soon as the ball begins to move, but if the gun were slung or were otherwise free to move horizontally, the recoil would commence at the same instant as the motion of the ball, and the quantity of motion in the recoil would be exactly equal to that in the flight of the ball, neither being supposed to meet with any horizontal resistance.

Since writing the above, I have read in the Times an account of a successful trial of an Armstrong

GENTLEMEN,-Mr. Atherton has put forward a statement respecting the new iron-clad ship, the Warrior, which presents in a very striking manner, the very disadvantageous as well as onerous conditions under which vessels of this kind are built, and especially if it be desired to raise the speed from 14 to 18 knots an hour. But I think he puts the matter in the latter case in rather a worse light than is necessary, inasmuch as though it may be requisite to have an increase in size, from 9,000 tons load displacement to 15,000 tons, it is not required that it should be by an enlargement on the exact model of the Warrior. If it be indispensable for a ship of this class to have a speed of 18 knots, and to carry sufficient coals to last three days at this rate at leastand surely it is none too much-would it not be better to effect the enlargement, in any future ship, in length alone; by which the proportions of a new Warrior would be brought to about those of the Great Eastern, though still falling greatly short in size. To see what may be gained in this way, I send you the following Table, in which the performances (in the relation of velocity to fuel) of the Warrior (W), the lengthened out Warrior (WL), and the enlarged Warrior (WE), are placed in juxtaposition. I accept Mr. Atherton's statement, that as in this case of 9,000 tons displacement, only 950 tons are available for coal, so in the case of 15,000 tons, the provision will not be for more than for 1,338 tons of coals, that is to say, if extra engine power is to be provided for the maintenance of 18 knots the hour; otherwise, let me whisper in his car, the coal as being the equivalent of mercantile capability, would follow the ratio of the displacements. But have we got the proper data of the Warrior's quantum of coals?

TABLE OF COALS CONSUMED PER DAY BY THE THREE
VESSELS.

THE WAVE-LINE PRINCIPLE. GENTLEMEN,-Having many years ago, when engaged in yachting, been interested in Mr. Scott Russell's "wave theory," I recollect finding some difficulty in the application of his system to the stern of vessels. Your recent notice of the transactions of

the Institution of Naval Architects has brought this

obliged if any of your readers would explain the subject again under my notice, and I should feel

matter.

I presume that from the bow to the widest or midship section of a vessel the lines should be so constructed that (with due allowance for other considerations) the resistance to the vessel in motion should be a minimum, and that from the same section to the stern the resistance should be a maximum.

epicyeloidal curves being the forms of wave lines at Mr. Scott Russell's principle, I believe, is this, that different depths, should be the types of the lines of ships, inasmuch as they are probably the curves of least resistance, being those which water naturally assumes when put in motion.

That this principle, viz., that those curves which belong to the back, or retiring portion of a wave are applicable to the bows of a vessel, when a minimum resistance is required, I understand, but that the curves which belong to the front or advancing portion of a wave are applicable to the stern of a vessel when from similar reasoning it would appear that the result a maximum resistance is required is not so clear, as would be to give a minimum resistance, where I apprehend the greatest force is desirable to assist the vessel in its onward course, as well as to counteract the elevating tendency of the pressure on the bows. I may, however, have erroneous conceptions on these points, and a few words may probably explain where the error lies. Yours obediently, M. A.

BOAT-LOWERING INVENTIONS. GENTLEMEN,I am well aware your columns are no fit medium (if fit medium there be) for a contentious, undignified correspondence; still I trust you will kindly grant me a little space to answer a letter in your Magazine of the 4th inst., couched in somewhat unparliamentary language, and signed Charles Clifford.

He talks of "gross misstatements," and "untruths,' but as I have the highest authority for every one of my statements, I cannot withdraw them, and beg to enclose documents for your private perusal (not hav ing time to receive permission from the writers to publish their names, many of them being on foreign service), from men of undoubted honour, in support of all that I asserted in my former letter.

The columns for days give the periods for the en- Mr. Clifford complains of unfair treatment by the durance of coals at the several velocities for the Admiralty. When he first took out his patent I do different vessels. The speed at 14 knots is made unit, not know; but some five years or more ago, when his and the consumption at that velocity for one day is plan had been brought before the public, it was detaken at 152 tons, being the asserted amount of coals cided to be the best plan then extant, and the Admicarried by the Warrior, divided by the asserted num-ralty permitted any captain of a man-of-war who ber of days they will last. All the other figures and desired it to have his boats so fitted. Had Mr. Clifconclusions are obtained by deduction from this as- ford any idea of the vast number of inventors who sumed fact. Thus column No. contains the ratios of besiege their lordships with petitions to grant trials the cubes of the velocities, when the unit is put at of their plans, some the most absurd-for instance, a 152 tons consumed at that velocity per day, in order would be less indignant at any little delay that may 14 knots; and those become the multipliers of the propeller without a motive power, a positive fact he to get at the respective velocities, the daily consump- have occurred in granting the request of an unknown tion in columns 3 and 5. Of course the assumption inventor. It is true the Admiralty shewed every is, that no greater propelling power for the same velo- courtesy to the late gallant Captain Kynaston, when cities is required for WL than for W. It may even he requested a trial of one of his many plans for savbe less with finer lines. The seventh column is ob- ing life, a subject which had occupied him more or tained by multiplying the fifth column with the ratio less since 1849 (vide a book, "Casualties Afloat," pub(141) of the areas of the midship sections in the two lished by him in that year). The said plan was displacements. This column differs very slightly from afterwards abandoned by him as uncertain in its Mr. Atherton's calculations, for he has therein put operation; for, as he truly said, "a plan for saving his formula, although containing the very frequently life must never fail." But Mr. Clifford must refaulty factor D3, to both a correct and a legitimate member that Captain Kynaston was not only favourThe result is, that by a lengthened-out Warrior ably known to their lordships as a successful inventor, instead of an enlarged one, we save 62 tons of coals but was one of their own officers, having served afloat daily at 14 knots, and 132 tons daily at 18 knots; and 27 years; had received their thanks on more than gain 2 more days of steaming at the one velocity, one occasion; had fought for his country; had and one day more at the other. If 10 knots were the saved a 90-gun ship from falling into the hands ordinary speed of the vessels, there would be 24 days of the enemy, and was at that very trial suffering consumption on board of the one, and 17 on board of from a wound, which has since brought him to an the other; and if we shorten each by six days ordinary untimely grave. consumption, and expend it in one day, each vessel would reserve enough to have one day of speed at 18 knots per hour. So that with this last kind of practice, the advantage of the longer vessel over the other, in point of endurance, would be even as 18 days to 11. This also is the advantage gained over the Warrior, together with one day's steaming at 18 knots, which this vessel cannot accomplish at all, for want of the requisite power in engines and boilers. This, at the best, then is what we should gain by the immense extra size and cost. Alas!

use.

BENJ. CHEVERTON.

With regard to the pendants breaking, the enclosed authorities of some of our best naval men, who have used them, will prove my assertion that they are not trustworthy after three months constant use, and this not from the usual wear and tear, but from the shortness of the nip. It is very likely a line of battle ship may have had her pendants 18 months, but Mr. Clifford does not say how long they have been worthless. Possibly he may have been misinformed on this matter. The slip hooks will not wear out in 18 months, nor in as many years probably-some trifling saving.

About the Exmouth. The trial took place in June, 1859. The boats were lowered several times, and Mr. Clifford's constantly hung-went down with a surgefirst one end, then the other, and on one occasion so perpendicularly as to alarm some fair spectators on result was, the captain discarded the pendants, and board. The hooks worked as they always do, and the

had both cutters and the stern boat fitted with

praised the pendants I cannot say, not knowing of Kynaston's plan. Who the "commandant" was who such a personage on board a man-of-war; but having the pleasure of the captain's acquaintance, I not only heard his opinion viva voce, but have it in his letter, which I enclose.

A similar occurrence took place with H.M.S. Topaze. The captain had seen neither plan, and requested a trial of both that he might decide. Clifford's boat was lowered first, and when close to the water's edge the pendants jammed, the boat hung, and, spite of the calm weather, a serious accident was appre hended; the engines were stopped, and the port cutter, fitted with Kynaston's Hooks called away to the rescue. The captain said, "It might be a very good plan, but if liable to such accidents, he would have nothing to do with it, and requested the hooks for both cutters. Many eye-witnesses can prove the above, and I enclose the authority of a naval officer of some standing, who was on board at the time. As to the trial of the Bacchante I will not use Mr. Clifford's uncourteous language, but would rather believe he has been misinformed than say he tells an untruth. I was particularly interested in that trial, and enclose the letter I received on the

subject. The boats were lowered three times; 1st. going two knots, Kynaston's boat cleared first, and re-hoisted, and Kynaston's boat had to wait fifteen was three lengths in advance of the other, they were minutes by the watch, whilst Clifford's pendants was being rove; 2nd. lowering, going eight knots, both boats equal; 3rd time, either purposely or accidentally, the man attending the foremost fall let it go. Mr. Langford, Capt. Kynaston's agent at Portsmouth, was in the boat, and seeing her going down by the bow, let go the disengaging line, and she fell, as usual, with even keel on the water, but shippel none. Mr. Clifford's boats worked well, but the cap. tain said he preferred the hooks, and he went to sea with both plans.

I have asked many sailors how long they are reefing the pendants; a quarter of an hour is the usual answer, but some have said with a smart crew it might be done in ten minutes.

With regard to the Austria, my informants were two of the survivors, and as they merely answered a casual question, and had no motive for saying Mr. Clifford's boats were swamped, I felt assured they spoke the truth. What I meant by concealment from the press was, that these accidents are never published, but if Mr. Clifford really wishes it, I can procure authentic accounts, for you to do so. About the collision at night, I do not know what is referred to, no names being mentioned. The case of the Trafalgar, Mr. Clifford's refers to, occurred in the autumn of 1859. I perfectly remember it, and hearing a man they laughed a little and replied, the man had swam had been saved by his gear; on its being said to two of the warrant officers it had done them good service, could be got down. The instance to which I referred to the ship and climbed up a rope, before the boat was of later date, about two months ago, and the enclosed document from a petty officer, who himself went down in the boat, seemed to me sufficient grounds for believing him.

I do not for a moment deny that Mr. Clifford's plan has saved many lives, I know it has, but I also know it often fails, whereas the hooks never fail.

Mr. Clifford's marvellous assertion of falls 200 yards long at either end of the boat, fairly takes away one's breath. The falls are rove thrice, and reach from the water's edge to the davits, now 200 yards divided by three gives 200 feet. I imagine a how-many decker, towering 200 feet above the bosom of the ocean! True, we are building larger ships every year, but I doubt if any naval architect, even in his wildest dreams, ever saw such a vision as Mr. Clifford's astounding assertion calls up.

The fact is the davits of a three-decker are from 35 to 40 feet from the water, the falls, therefore, are 35 or 40 yards long, not 200. Now the pendents must not only reach to the water, but must pass along the bottom of the boat (say to a 30 foot cutter) and have half a fathom at each end to spare for the roller, so his pendants are exactly 58 feet each or 116 feet for every boat of a line-of-battle ship's size,and it strikes me if Mr. Clifford were struggling in a heavy sea with not even a life-buoy, he would rather Kynaston's boat, which is always ready for lowering, were sent to his

aid, than wait till his own 116 feet of perhaps hard, stiffened rope, were rove on his roller.

With respect to Mr. Clifford's challenge about lowering a boat regardless of weather, speed, or position, I would fain ask him, first, would he lower and clear a lee boat, the ship having lost her way, in half the time Kynaston will? Secondly, after heavy weather, when his pendants are hard and swollen, and will not reeve through his blocks, or are perhaps frozen on the roller, will he lower once before Kynaston lowers, rehoists, and lowers again half-a-dozen times? Thirdly, will he lower a stern boat from a ship going any speed? I have heard of its being tried and the boat swamping. Now the hooks answer perfectly in a stern boat, vide the numbers that are so fitted, and that the hooks are preferred to the pendants is proved by the fact that most captains who have once had the pendants for any time discard them for the hooks: H.M.'s ships Caesar, Diadem, Royal Albert, Jason, Renown, Exmouth, Centurion, and many others 1

could name are instances.

And now, gentlemen, let me thank you for your increasing courtesy to me, but not being exactly a British officer, and having no desire to enter a personal altercation with so uncourteous a writer as Mr. Clifford, I fear I must still retain the objectionable incognito, assured my own well-known name and the documents I enclose, are sufficient guarantee to you of my good faith, and leave it to time and the descerning public to say, whether I erred in subscribing myself,

Your most obedient servant,

PALMAM QUI MERUIT FERAT.

[Notwithstanding the concluding sentence of our correspondent's letter, and notwithstanding also the extraordinary certificates with which the letter is accompanied, we cannot think it just to Mr. Clifford to permit this discussion to extend itself with one of the parties to it concealed. We shall, therefore, only permit a short reply from Mr. Clifford (to which he is, we believe, entitled)-should he desire to replyto appear hereafter, although our advertisement columns will of course be open to the disputants.EDS. M. M.]

AUXILIARY RUDDERS. GENTLEMEN,-With reference to a letter in your Magazine for January 11, from Captain Beadon, R.N., in which that gentleman claims to be the inventor of the auxiliary rudder you illustrated and described as my invention, I beg to say that I have examined his specification bearing the date named, 12th Oct., 1858, and that there is nothing mentioned in it having the slightest resemblance to the "Auxiliary Rudder" invented by me.

I am, Gentlemen, your obedient servant,

W. R. MULLEY.

THE DESCENT OF THE DEEP-SEA LEAD. GENTLEMEN,-As an error is always the more worth correction the more notable the authority, permit me to point out one very commonly accepted, and occurring in the valuable paper of Mr. J. W. Tayler, F.G.S., in your number of 11th instant.

It is there stated that "all who have sounded in deep water know how slowly a body (even lead) sinks in very deep water; it therefore appears that no boulders detached from icebergs can ever injure the cable."

pencil, which pencil may be made to press upon a card by means of a spring, so that when this card is moved horizontally as the pencil may be raised or depressed by the rise or fall of the mercury in the thermometer, a waving line may be traced upon the card. Let this card be fixed in a frame, and so moved by clockwork moving through a given space in a given time, say twenty-four hours. If such cards are printed, each having its appropriate month and day of the month and hours marked upon it, it may be taken out at the end of the twenty-four hours, and replaced by another. These cards may then be laid aside and compared, and their results registered at any convenient time afterwards.

cations, somewhat in the same way, by employing a A register barometer may be made to give its indiflat instead of a round tube of glass, with a strong light in front, and having the cards prepared like a photographic paper, the light being intercepted by the mercury, and falling only on the prepared cards above the level of the mercury in the barometer. I am not aware that instruments of this sort have of any interest or use, a place in your Magazine for it ever been prepared before. If you think the scheme will oblige, Yours, A. RAY.

Shipping Office, Dundee, Jan. 18, 1861.

P.S. I shall give you, by-and-bye, a new scheme of a doubly-acting air-pump, much simpler, I think, than anything hitherto proposed. In ordinary pumps the pump plate requires to be a perfect plane, which makes it very expensive, as such a plate is not easily made. Besides all the receivers must be grooved to fit the plate truly. Could not this be obviated by covering the plate with a sheet of india-rubber, say a quarter of an inch or so in thickness.-A. K.

Iron Works, Spalding, Jan. 23, 1861. GENTLEMEN,-Although we are constant readers of your valuable Magazine, a letter relating to us in your number for the 21st ultimo, escaped our attention.

The letter in question, by Mr. William Baddeley, has since been shown to us, and we feel assured that from your love of fair play you will publish our reply Mr. Baddeley occupies a column of your valuable space with a letter in which there is no other apparent object than that of underrating, and speaking in disparaging and slighting terms of our generallyacknowledged valuable invention, and we cannot help expressing our surprise at his unbusinesslike and unhandsome attack.

state of degradation, all mine will be consigned to oblivion, the accumulation of sixty-five years, my first mechanical contrivance being made in the year 1795. What would this country be if literature had been so scandalously trammeled?

With thanks for a previous notice you took of a letter of mine on the subject,

I am, yours obediently,

J. P. DE LA FONS.

PATENTS FOR INVENTIONS.

January 23, 1861. GENTLEMEN,-Would you be so kind as to favour me with a few particulars relative to the taking out of of improving a scientific instrument already much in a patent. A friend of mine has discovered the means use, but most defective in organization; will it be necessary to have a complete patent or a patent of improvement for it, and what would be the expense of either? Is there not also some means for a provisional protection, if such should be required? Hoping you a subscriber, and trusting that you will oblige me, I will excuse my troubling you on the ground of being am, your most obedient servant,

PHILO.-MECHANICS.

[The patent must be taken for your friend's improvements. The cost of a patent, including agent's fees, is from £40 to £45. The provisional protection (which is the first step towards a patent) costs, including agent's fees, £10 10s. If you will send us EDS. M.M.] your address, we will forward you fuller particulars.—

LOCOMOTIVE BLAST PIPE.

GENTLEMEN,-I take the liberty of asking if you (or perhaps some correspondent) through the medium of your valuable journal, could direct me to the earliest published account of the variable blast-pipe in locomotives, and you will much oblige, yours truly, A CONSTANT READER.

MEETINGS FOR THE WEEK. Mox.-Royal Geographical, I., "North Atlantic Telegraph," by Captain Sir F. L. M'Clintock, R.N., F.R.G.S., of H.M.S. Bulldog, and Captain Allen Young, F.R.G.S., of the Fox; II., "Explorations in the Faroes and Iceland," by Dr. John Rae, F.R.G.S.; III., "The Fjords of South Greenland," by F. J. Tayler, Esq.; IV., "Electric Circuits," by Col. Shaffner, F.R.G.S., at 8.30 p.m British Architects, the Special General Meeting for discussing the "Varions Processes for the Preservation of Stone," at 8 p.m.

London Inst., "On the Relations of the Animal Kingdom to the Industry of Man," by E. Lankester, Esq., at 7 p.m.

Mr. Baddeley designates our invention as a "modern antique;" we are unprepared to say whether an engine, upon the same principle as the one made by us, was in use in ancient Rome or Greece; but although we are reminded that, "there is nothing new under the sun," we distinctly assert that our engine is not the same as M. de la Hire's double-acting pump made some century ago, and we have invented TUES.-Inst. Civil Engineers, Continued Discussion upon and patented an engine which we are satisfied is perfectly new.

We condole with Mr. Baddeley upon the time which he devoted (and which he terms misspent) in endeahis failure will not cause him to "run down" those vouring to perfect a pump, and trust that in future

whose exertions have been more successful.

The best answer, however, we can make to Mr.

Medical, Election of Committee.

Mr. Braithwaite's Paper "On the Rise and Fall of the River Wandle," at 8 p.m.

Royal Inst., "The Comparative Anatomy, Physiology, and Fossil Remains of the Class of WED.-Society of Arts, "On Food; its Adulterations and Fishes," by R. Owen, Esq., at 3 p.m. the Methods of Detecting Them," by Mr. Wentworth L. Scott, F.C.S., at 8 p.m.

London Inst., "On Physical Geology and Geography," by E. W. Brayley, Esq., at 7 p.m.

Baddeley's petulant letter, is to refer him to our numerous valuable testimonials, and although he may consider ours to be a worthless invention, we confidently challenge any maker in England to bring THURS.-Royal Inst., "Electricity," by John Tyndall, an engine against ours, that will do the same amount for the length of this letter, of work, with the same quantity of labour. Apologiz.

London.

We remain, Gentlemen, yours obediently, BLINKHORN, SHUTTLEWORTH, & Co.

THE PATENT LAWS.

13 Carlton Hill, St. John's-Wood, January, 1860. GENTLEMEN,-As mechanicians are deeply interested in a law that has swindled thousands of talented individuals out of their birthright, myself alone of two and twenty inventions, some of them of great importance, I send you a copy of a journal that espouses the cause of those whom the patent law has robbed of their inventions, a law that heartlessly crushes the poor artizan, numbers of whom have pined away their days in wretched poverty and regret, although they had mine of wealth in their fertile brain, as no invention of importance can possibly be brought to perfection but by its inventor. At the close of the coming session of Parliament if genius be not rescued from its present

The News of the World.

Esq., F.R.S., at 3 p.m.

Royal Soc., at 8:30 p.m.

Royal Academy, Sydney Smirke, Esq., "On Architecture," at 8 p.m.

FRI.-London Inst., "On the Principles and Applications of Vegetable and Animal Chemistry," by T. A. Malone, Esq., F.C.S., at 7 p.m.

Royal Inst., Rev. A. J. D'Orsey, B.D., "On the
Study of the English Language as an Essential
Part of a University Course," at 9 p.m.
United Service Inst., Rev. H. M. Grover, "The
British Tides," at 3 p.m.

SAT.-Royal Inst., "Inorganic Chemistry," by E. Frankland, Esq., at 3 p.m.