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103 else remained the same. To the 2nd I would as was thrown in; and when the air-pump first observe, that in the common engine is only a single-acting one, this accumulaevery alternate stroke has to eject the con tion is again doubled. All this I have said densement, therefore there must be some over and over again, and nothing but this irregularity here; but in mine, half that can be inferred from it ; not that I suppose quantity is ejected at the termination less is taken out than is thrown in. I am of each stroke, (calling, here, half a obliged, however, to N. N. L. for his notice, revolution a stroke.) As to the injurious and shall be happy to meet him again, if he effect of ejecting the condensement in so is not satisfied with my hasty reply.-J. P. short a period by a large piston, “when the crank is in the worst possible position to carry on the movement of the engine," I must say I consider the contrary. Those

PILBROW'S CONDENSING CYLINDER well acquainted with the steam-engine, and its precise regulation, know that it is de. Sir,—This invention has been so much sirable that all the momentum and elastic discussed in your pages, that I should not force of the steam, above the amount neces join in it, but for my promise some time sary to simply overcome the friction of the back, particularly as Mr. Pilbrow has, I engine, should be taken from it before the think, answered satisfactorily the objecturn of the stroke, so that it should not be

tions made to its principle. Whether, expended upon the matter of the machine however, there will be that perfect equiitself. To accomplish this, it is the practice librium necessary to give it so great a in many of the best engines to let in the steam upon the eduction side of the piston,

superiority over the present engine, is a before the stroke is quite completed, or in

point that practice alone can determine, shutting the late eduction valve, and opening

though I do not see any theoretical law the contrary, prior to the turn of the piston,

to prevent

it. to bring all to a perfect and positive easy

In Mr. Pilbrow's reply to my question, rest. Now, such proceedings are accom

respecting the consumption of fuel by panied with loss of duty and steam ; but the best marine engines, he has shown when the engine is properly regulated, the

the difficulty of determining the quantity momentum acquired by the descent or ascent with any accuracy, owing to the frequent of the pistons, and all the machinery there. variation of the actual power by cutting with connected, will be taken up by force off the steam at different parts of the necessary for the expulsion of the condense

stroke. I regret I cannot help him to a ment, &c., to the atmosphere. This action

nicer appreciation; but there are few will not be a sudden jerk or concussion, as facts taken with sufficient accuracy to desome have supposed, (as I have before fully

termine the real amount; and it is to be explained,) but a gradual oozing, rather, of

lamented that the suggestion of one of the condensement; when the momentum of the matter has the greatest power over the

your correspondents has not been adopted, cranks, instead of the worst; when the

and the returns of fuel consumed made crank may have to move twelve times as

in the form of his log. Until this is fast, and twelve times the distance of the

done, I think no dependence can be condenser piston, which gives, of course, placed on bare statements of only 5 lbs. that proportion of mechanical advantage. If per actual horse power, from whatever N. N. L. doubts the accumulation of power, quarter they may come; for I have or a concentrated force doing as much as a little doubt that this return has been ** diffused ” force, let him think of the made from the total quantity of coals various stamping machines. As to that part consumed on a voyage, calculated upon relating to the better vacuum and the accu the extreme actual power, worked to the mulation in the condenser, although N. N. L.

utmost, when the diagrams have been has in great measure answered himself, and

taken, but which extreme has not been saved me the trouble, I shall simply say,

continued more than one-fourth the that when there is a separate condenser, ac

whole distance. cording to the proportion the same bears to

Although I think it will be found, on the air-pump, so will the accumulation of gases be; for if the air-pump is of the same

a proper comparison, that, making allowcapacity as the condenser, then must there

ance for the gain in duty by expansion, be, at the time the air-pump makes its

the engines of the present day consume, stroke, double the quantity thrown in by on the average, nearly as much coal as the steam cylinder and injection each stroke, the average of Mr. Watt's engines, there or the air-pamp could not take out as much is certainly not so great a difference be

the vague

tween the cylinder exhaustion and con probably find it better in practice to indenser vacuum of the best modern en. crease the area of his condensing cylinder, gines as in those of Mr. Watt; and the (keeping the capacity, of course, the same apparent improvement in modern prac as the steam cylinder,) as its speed will tice is so great, that it ought to give a be double that of the present air-pumps, corresponding increase of duty, but it which might render the discharge of the does not. Either the results, therefore, condensement somewhat inconvenient. of Mr. Watt's engines, given by Mr. This additional speed may prevent the Farey, are inaccurately reported, or no speed of the piston being increased to reliance can be placed upon

400 feet a minute, as Mr. Pilbrow conand ever-varying assertions of consump templates, to obtain double the power in tion of the present engines. Whatever

the same space. may be the cylinder exhaustion of the There are now four inventions before average of engines, the best, using steam the public, of the very highest importance expansively as low, nearly, as it can be to steam navigation; sound in principle, used, are within three-quarters of a pound and, except the first, amply confirmed by of the condenser vacuum; an approxi. practice. The condensing cylinder enmation as near to perfection, probably, gine of Mr. Pilbrow; the condensation as the 'action of the steam-engine will by injection, to prevent incrustation, of permit. But I certainly agree with Mr. Mr. Symington; the prevention of smoke Pilbrow, that this excellent evacuation is of Mr. C. W. Williams; and the screw proonly obtained by an equal loss of steam peller of Mr. Smith. Britain, it is grapower, by opening the exhausting valve

tifying to see, still maintains her station, before the completion of the stroke; so the first in the mechanical and useful that there is a total loss equal to 1} lbs. arts. She has now put at the disposal on the square inch, even in the best en

of commerce new means of extending it, gines. Assuming, then, that Mr. Pil.

of removing many acknowledged evils of brow's engine will maintain an equi steam navigation, and yet what an amount librium throughout the stroke, there can of prejudice has talent to overcome! be no doubt, I think, that it will be su

People will not believe their sight! perior to the most excellent marine en

Every thing changes-states, cities, emgine that can be made, to the extent of pires, nations, the earth and sea—all pro14 lb. the square inch, in this particular, gressing to some wondrous close ; but and probably to half a pound more for a the human mind remains “cribbed, cabetter extreme vacuum, giving a total bined, and confined,” bound up in preju. gain of 2 lbs. That such an invention dice, and we see now in operation what must inevitably supersede the separate so long retarded the introduction of Mr. condenser engine of Mr. Watt, I see Watt's engine, three quarters of a cenno reason to doubt, and I cannot give

tury ago. Is it written that the mind the talented inventor higher praise. It alone shall never progress from a bondcertainly has the merit of being the

age that has in all ages debased it! most original, as well as the soundest

I am, Sir, your obedient servant, based improvement on the steam-engine

SCALPEL. since 1765, amidst the thousand at. January 29, 1842. tempts made since then to improve Mr. Watt's. S. has justly observed, that Mr. Pilbrow's engine is contending with a substantial, not a shadowy

MALLET'S HYDRO-PNEUMATIC BUFFERS defect in the present engines ; and as

IMPROVEMENT SUGGESTED. it is yet more simple than Mr. Watt's, Sir,—It is with some degree of diffiand cheaper, it seems to me that Mr. dence that I come forward to suggest Pilbrow may claim the merit of having an improvement in the invention of a brought the reciprocating engine to practical engineer, like Mr. Mallet ; who the highest perfection of economy in may be supposed to have well considered fuel that its nature is capable of. It the precise bearing and effect of his comseems to me that the condensing cylinder binations, and to have adopted the best engine is a valuable contribution to me and most appropriate means, for making chanical and philosophical science. his invention practically perfect. I make

To prevent any jar, Mr. Pilbrow will this observation, preparatory to referring


105 to a part of Mr. M.'s ingenious hydro- partly) hollow plunger B, which works pneumatic buffers, described in your No. through both ends of the cylinder in 956, which has struck me as far from stuffed collars, and is divided into two exhibiting the adaptation of well devised equal parts 1, 2, by a metallic plate or means to obtain the best results. I allude diaphragm, which projects so as to be cato the means adopted by Mr. M. for pre- pable of being formed by any appropriate venting the plunger being driven out of means into a piston, working smoothly the cylinder by the rebound or recoil of in the cylinder. One end of the plunger che compressed air, which is done by pro is armed with the usual buffer-head; C, jecting fillets cast on the inner end of the the other end, is plain and concealed in plunger, which impinge against the cy the frame work of the carriage. The linder on the recoil of the plunger. But, apertures of the two air chambers of the so far as I am able to understand Mr. plunger, communicating with the cylinM.'s description, his invention contains der, are near to each side of the piston no provision for preventing or counter and in the lowest part of the plunger. acting the sudden shock or concussion Now it is obvious, that if the air in with which the inner end of the plunger each division of the plunger be in an must thus be driven against the cylinder equal state of compression, the latter will by the reaction of the compressed air. necessarily be in the position represented

A very simple expedient offers itself, in the drawing with the piston exactly in by which the plunger may be as effec the middle of the cylinder, and the buffer tually prevented from being driven out at rest. On coming into collision with of the cylinder, as it can by fillets or any another body, the buffer will be driven other mechanical resistance, while at the in, more or less, according to the force of same time the possibility of any shock or the collision, and the air in the farther concussion is entirely obviated. For this chamber (2) of the plunger compressed purpose it is only necessary to employ a accordingly. But whatever may have double hollow plunger, divided into two been the

force of the collision, and degree equal parts and working through both of compression, the plunger cannot, on ends of the cylinder. The following fig. removal of the impulsive force, fly back and accompanying description will render or rebound with a sudden shock against this more plain.

the end of the cylinder as in Mr. M.'s

arrangement: for as soon as the piston C

passes the middle of the cylinder on its return, the air in the near compartment

(1) of the plunger begins in similar manB

ner to undergo an increasing compression, which will not only destroy the force of the recoil, before the piston comes near the end of the cylinder, but re-act on the opposite end, in its turn; thus establishing an oscillating motion of the two ends of the plunger, until the

buffer fioally comes to rest, with the A

piston in its old position in the middle of the cylinder.

As a concluding suggestion, let me ask whether oil would not be a better fluid for using in the cylinder than water ? Oil would lubricate and make the dif. ferent parts of the buffing apparatus work with greater ease and delicacy of movement;

and the freezing point of certain oils is considerably lower than that of water. The quantity required for each buffer would be trifling.

N. N. L. A is the cylinder, truly bored, and

January, 1842. amewhat longer than the double (and


MR. C. W. WILLIAM'S IMPROVED BOILERS of alum, I should not like to have the -IMPROVEMENT SUGGESTED. task of setting them on fire with tbe best

roche à feu, (in English, wild- fire, or carcass composition,) even my OYD, which Woolwich authorities have told me is stronger than Congreve's; it burns a hole through an iron plate, and consumes an iron bolt, a quarter of an inch diameter, in a few minutes.

Whilst I have my pen in my hand, I will take the liberty to touch upon an

other trifling thing or two, until I have Sir,-Will you permit me to recom time and means to give you something mend, through the medium of your jour- better, which will be soon. nal, the adoption of ribbed plates, as re “I hope I don't intrude," if I venture presented in the above sketches, in lieu to say a word or two about the Archiof Mr. C. W. Williams's cylindrical con. medean screw propeller for steam-resductors, one portion of which that gen sels. In your Number 961 there is a tleman admits there is a difficulty in in long account of “A Trip in the Architroducing, on account of their interfering medes” steam-ship. Now, although I with the removal of deposited matter. have already mentioned the fact, I do These ribbed plates would admit of a not think it impertinent for me to take great extent of heating surface, and the liberty of repeating it, i. e. that it would offer no greater obstacles to a was I who presented the plan, with cleansing process than common ones. models and drawings of this said screw I am, Sir, your obedient servant, propeller, to the Duke of Clarence, Lord

C. W. High Admiral, in 1837. Admiral Sir

Edward Owen was then his secretary, or chief counsellor; I have his letters to show that my plan was rejected as inefficient! Many other things, which on

occasion of the first war will surprise the PROPELLERS-THE BUDE LIGHT,

belligerents, were also disregarded.

So Sir,-In my letter of last week, on the much for that. prevention of fires, I forgot to mention Another item is, that I see a patent an effective means of rendering the thatch taken out for a light caused by the proof cottages, barns, &c., incombustible. jection of a jet of hydro-oxygen gas on It consists in soaking the thatch with to a cylinder of lime. It was Mr. Goldswhitewash made of lime, or whitening worthy Gurney who invented that mode and size, in the usual way, to every four of producing an intense light, at his regallons of which is added one pound, or sidence of Bude, in Cornwall, in the year

of alum. Alum would suf. 1825— at least, that was the year in fice by itself, but the rain would wash it which I first saw it. This light after. off. The lime and size foroi a film over wards got the name of the “Drummond every straw, insoluble in water. In July, Light”-how, I do not know: but Lieu1835, I covered a quantity of straw and tenant Drummond was a gentleman well perfectly dry furze with this cheap pre connected, and belonging to the British servation, and, after it was well dried in service! the sun, I endeavoured in vain to make The season and the weather prompt it burn. I do not pretend that this wash me to write a word on humidity. In can, with expediency, be applied to the 1816, I lived for some time near Tonvertical sides of a hay-stack,

because, bridge-wells, in Kent. In very dry sumfirst, it would not penetrate sufficiently; mer weather, I observed patches of grass secondly, the quadrupeds would not quite green, while others were brownlike it. Whether the wash would be dried up by the sun. I thought it right best applied to the straw before being to examine the cause, and, by a few bound into a thatch, or afterwards, a strokes of a spade, I found that there trial or two would determine. If deal was a stratum of chalk in contact with boards are well soaked in a strong solution the roots of the grass. This guided mi



rather more,


107 to several reflections. I thought that ing the ice; but upon a trip, which, sans chalk had a greater disposition to attract the basket go-cart, would have been a and retain the moisture of the atmo. fall, the machine, (if we may so call it,) sphere than other earths, and I have still rests and slides upon the ice, supporting reason to be of that opinion. I also ob the lady under the arms on a well-padded served that the large earth-worms, (lom rim. This is no joke, for I put it to a brici,) never came up to defile the turf successful test at Groombridge, in Kent,

hen it was upon a layer of chalk. So in 1816. However, I do not suppose the first application of my remarks was that the ladies will avail themselves of to persuade my friends Mr. Campfield, the suggestion. Mr. Saint, Mr. Woodgate, the banker, I hope that my next letter will contain and some others, who had their wives' something better than the trivialities of and daughters' shoes daily soiled by the this. By the by, Sir, do you know-I dare worms' projections on their lawns, to say you do-the origin of the word “triallow me to take up the turf, and replace vial?" The ancient Roman roads were it, after putting under it a thin stratum formed of a carriage-way, and a foot-path of chalk, broken about as fine as the coal on each side, as are most of ours; hence used in smiths' forges : but the finer the they were called tri viæ, or three ways. But better. I did all this in June, 1816, and the word “ trivial” used to mean, with pot a worm ever came up afterwards ; the ancient Romans, any thing well besides that the turf always retained its known, and common, and spoken of on verdure, in the driest weather. Some the high roads, or tri viæ. The triyears after, I observed on my garden umphal arch at Hyde-park-corner sins walks, during a frost, especially when sadly in having only one centre passage conjoined with fog, a circumstance which for carriages, which formation makes it went some way to confirm me in my look very heavy. All Roman triumphal guess at the humidity-attractive disposi arches have three openings—tri viæ. tion of chalk. I observed that a piece of I have the honour to be, Sir, chalk, exposed to the frost, accumulated

Your obedient around it more than five times its own

F. MACERONE. Teight of ice, and after a few frosty foggy January 20, 1842. nights, the bit of chalk became as a speck in the centre of the surrounding ice. After frequently remarking this fact, I bethought me of trying whether other substances would become equally covered Sir,- Being anxious to try some experiwith ice, under similar circumstances. I on voltaic electricity, and to conplaced in propinquity, on the same path

struct a large coil machine, but, for want of in my garden, bits of wood, orange-peel,

pecuniary means, unable to procure the recork, marble, iron, lead, and glass, all of

quisite quantity of "insulated copper wire," the same sizes and shapes. I have not

it occurred to me that fine tow might be so

thrown on as to answer the intended purpose. now access to my memoranda on this

I immediately applied to Mr. Dinmore, rope subject; but, as far as I can remember,

manufacturer, at Woolwich, and suggested the iron and lead accumulated no ice;

the possibility of effecting my object by the cork scarcely any; the orange-peel a stretching the wire from the wheel, and givlittle; the marble rather more; the wood, ing it a rotary motion, while it was fed side(deal,) a little ; but the chalk, after a few ways by a person walking : the experiment days' and nights'exposure, was surrounded was tried, and found to answer admirably. by at least six times its own weight of ice. Thus, by this means, an immense length of I leave this experiment in the hands of wire can be covered at a most insignificant philosophers to try at a cheap rate.

cost. To render it more compact and secure, Now we must teach the ladies to skait,

I give it a coat of some resinous varnish without the possibility of a fall whilst

after each coil on the reel. When a secondlearning. In 1816, I had constructed

ary wire is required, you have only to throw some bell-shaped things of wicker-work,

them together by the ordinary method of

spinning twine. just fitting round the chest, under the

By reference to the undersigned, any arms, but expanding at the bottom to

quantity of this wire can be procured. about four feet diameter-it might be

J. WALKER. more. Shoulder-straps prevent its touch Woolwich, January 11, 1842.




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