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for the painted ceiling at Whitehall

. Now, in possession of one, and if they will do all that is required for this useful imita- so for me, I shall be very happy to hear tion is black and red; for with these two the result. The glass disc may be made colours, and the ground, which is yellow, like the plate of an electrical machine, inay be produced a thousand different and may be conveniently set in motion tints.” Particular instructions for imitat- by a lowering weight. ing the marbles most in request, with a

I am, Sir, yours, &c., beautiful specimen of each, are then

S. M. NEWSAM. given. These are followed by some highly useful observations on preparing grounds, and polishing, which, did our space permit, we would willingly have transferred to our pages.

CONDENSATION OF STEAM BY COLD AIR. The whole plan and execution of the

CRADDOCK'S PROCESS. work is highly creditable to the artistical Sir,-With your permission I will lay skill of Mr. Moxon, who, in thus laying before your readers an account of my before his brethren of the trade, (or, patent condenser for steam-engines, and as the grainers say, the profession,) cor of a series of experiments made thererect models for their study and imitation, with; the latter of which will, I trust, has done much to promote a taste for demonstrate that the condensation of simplicity and chastity of design, which, steam by the cooling effect of air, hither. being founded in truth, never fails to re to considered impracticable, is not only alize more or less of the perfection of within the reach of possibility, but can beauty.

be effected with such facility as to render its adoption general in those situations where å supply of water is not to be pro

cured. FROM THE SOLAR AND OXY-HYDROGEN The peculiar feature of my invention

is, the communication of a rapid motion Sir,- I have read lately, in the Philoso to the condenser; independent, of course, phical Magazine, vol. x. p. 184, a descrip of the motion which the vessel or locotion of a method of cooling, by a current motive may have, to which my condenser of air, the heating effect on the objects is attached. It will be unnecessary for exhibited in the solar and oxy-hydrogen me to detail my preliminary experiments, microscopes. The object is stated to or the various forms which I have given have been accomplished by the use of a to the condenser during my investigapair of domestic hand-bellows, and with tions: I will therefore at once describe complete success, the thermometer indi the apparatus in that form which, from cating the temperature to be as low as my present experience, seems to me the 60° Fahr.; so that, to quote the words of best. A hollow axis is supported by the writer, “our solar and oxy-hydrogen proper bearings in a vertical position. microscopes, instead of being used for The lower end, or that at which the steam purposes of amusement only, and limited is introduced, is open, and works on a pivot to the exhibition of objects which are un fixed on the bottom of a chamber, on the affected by heat, may henceforward be top of which is a stuffing-box, through employed for purposes of scientific in which the axis passcs. Near the upper or vestigation, and thereby assume the more closed end of the axis is an enlargement or important rank of valuable philosophical chamber, from which proceed, at right instruments.” In furtherance of these angles to the axis, a number of radial holviews, I beg to propose the use of a re low arms, into each of which the ends of volving disc of glass, the lower half of a series of small copper tubes are inwhich ought, probably, to be immersed serted; these, of course, are parallel to in a trough of water, the upper portion the axis ; their lower ends are inserted passing over the objects in a space be into other radial arms fixed near the bot. tween them and the condensing lenses. tom of the axis, and similar to those at Not having an instrument of the class by top, excepting that their ends do not me, I have not had an opportunity of open into it. The radial arms at the testing the value of this suggestion ; yet bottom are all connected by their ends there are, no doubt, some of your readers opening into an annular chamber. A


NEW AND SIMPLE METHOD OF OBTAINING MEZZOTINT GROUNDS. 247 rapid rotary motion is given to the con equal to 20 miles per hour, and the denser by the steamn-engine to which it water being drawn off at 150°, will reis attached; the result of which is the quire about 2 ) square feet of surface per cooling of the apparatus, and, conse cubic foot of water per hour. The quently, the condensation of the steam strength of the copper I have hitherto which has been introduced into the small used is 1 lb. to the square foot, but I incopper tubes. The condensed steam or tend using it much lighter in future. water falls into the lower radial arms, The weight of a condenser equal to conand is thrown from thence into the an dense 10 cubic feet of water per

hour nular chamber by centrifugal force; a will be from 8 to 10 cwt. small pump is affixed to this chamber, Besides the advantages which my mode and its piston-rod is attached to the clip of condensation possesses, in those situaof a fixed eccentric supported round the tions where a supply of water cannot be movable axis of the condenser. As the had, I believe it possesses other, and pump travels about this eccentric, its scarcely less important ones.

By my piston-rod works to and fro, and the condenser returning the water to the water is removed from the condenser. boiler, I am enabled to use a tubular The arrangement of the minor parts of boiler, without experiencing that inconthe apparatus, such as the conveyance of venience which almost precludes their the water to the boiler, the connexion of use in combination with the ordinary the air-pump, &c., cannot be illustrated system of condensation, namely, the liawithout drawings. I may just remark, bility to become choked up by the deposit here, that the force-pump for the re from the water. Although the condenser moval of the water is not absolutely ne with which I am working is far from cessary, as the air-pump may be made to being tight in its various joinings, I have effect that object. My experience, how worked my engines constantly, for four ever, demonstrates that it is effected to days, without adding any water to the greater advantage by its use.

boiler; and I have no doubt that the I have attached a condenser of this condenser and engine I am now fitting kind to a high-pressure engine of five up, and to which I hope very soon to be horses' power, and, by giving it a velo able to call the attention of engineers, city of 11 miles per hour, the water is will give results even more satisfactory drawn off at a temperature varying, with than those at present obtained. that of the air, from 90° to 120° Fahr. In conclusion, I have only to remark, The column of mercury supported by the that the apparatus and engine with which vacuum is not quite so high as it should the above results were obtained may be be, according to the temperature of the inspected by any parties who feel interwater; this, however, is owing to the ested in the matter, at my manufactory, imperfection of some of the joints in the 350, Coventry-road, Birmingham. condenser, and will soon be remedied.

I am, Sir, &c., The power gained is more than double

THOMAS CRADDOCK. that required to work the condenser and air-pump. The amount of surface required to condense a given number of cubic feet of water per hour depends

MEZZOTINT GROUNDS. on the velocity at which it is intended to Sir,--It gives me some pleasure to be work the condenser, and the temperature

able to announce that I can form a toat which the water is drawn off. It does lerably good mezzotint “ground" on a not appear to me advisable to draw the plate, by passing it along with a piece water off at a temperature lower than of common sand paper five or six times 150°, for a given abstraction of heat at a through the rolling printing press, with lower temperature affects the height of rather a tight pressure. The depth of the mercurial column much less than at colour, when printed from, does not quite a higher; and any one familiar with the possess the intensity of those executed law according to which heat passes from

in the usual manner; but the method one body to another need not be told, answers exceedingly well for prints which that the same surface will condense much are intended to finish in colours. more steam into water at 150° than at Sir, I remain your obedient servant, 100%. A condenser having a velocity

LAURENCE BRUNTON. March 14, 1812.


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Sir,—The prefixed sketches represent the back bar g, which turns in brass an improvement in the lathe, which bearings, fixed to the legs of the lathe as I believe to be original, and have shown, and to the end of which is fixed found to add greatly to the ability of this the upright rod d, communicating with valuable instrument. The figures are on the crank e, by the connecting rod f. the scale of an inch to the foot.

It will be seen, on reference to fig. 1, I am, Sir, your obedient servant, that the crank e (which is fixed to the

H. CHILDS. shaft g, at the driving wheel,) has a Laughton, February 24, 1842.

groove in the middle of it, which allows Description.

the pin, to which the connecting rod f Fig. 1 is an end view of the lathe bed ; comes, to be shifted to or from the centre and fig. 2, part of an elevation of the and made fast at any required distance, same, with the front leg removed. a a as the case may require, by a nut and a a a, represent the lathe bed; cc the screw at the back. wheel ; b b the treadle, firmly fixed to

H, C.


INSTRUMENTS. Sir,--In your last Number, which has make the subject public, doubtless he has just been received, I observe mention a right to the invention. The method made of a new application of the electro was, however, proposed by me in Detype, by M. Peyré, for multiplication of cember, 1840, " for producing graduated graduated instruments. As the first to astronomical instruments from an original


249 one; also scales, dials, &c.; and probably any kind is required"-no "daily mainfor producing plates of marking in in tenance"—it is to work without any sects' wings, &c., for printing from." “wear and tear," saving only the “mere The plan was tried by me, but only to a loss occasioned by friction"-all that is limited extent, for the production of wanted absolutely

' is, but a little oil or scales ; the result of one experiment tallow to lubricate the parts occasionally being an electrotype scale, divided into -once a twelvemonth or so! Some of 100 of inches. A variety of circumstances our readers (we hope not many, however) prevented me from paying immediate at may by this time have pictured to themtention to the matter, or I should have selves that “ galvanism, or electricity" communicated the results to you. The must needs have something to do with plan of M. Peyré will, I have little doubt, this new miracle of invention. No such be of value, and the public will be in thing—the mystery lies a good deal debted to him for making them acquainted deeper.

deeper. Neither galvanism nor elecwith the further success of his process. tricity is of virtue enough for the acIt has occurred to me, also, that the complishment of such wonders; and “for electrotype process might be successfully this simple reason,” says Messieurs the used for producing tools for re-grinding projectors of the “Double Acting Roor polishing specula, as the tool might tary Company," that they are conthus be made from the speculum itself, vulsions of nature never intended by if of good figure; and any number could a Divine Providence for the use of be made from the original tool, as those man"!! in use altered in figure. Tools might Where then lies the grand secret ? In also be made from lenses, for the same a narrower compass than any thing so purpose. If you think these hints likely extraordinary was ever perhaps shrouded to be of service, perhaps you will insert before-in a nut shell verily. You have them in the Mech. Mag., and oblige, but to place an empty cylinder, one half Sir, yours respectfully,

in water, or any other fluid, and one half N. S. HEINEKEN.

in a vacuothat is, literally, all you are Sidmouth, March 18, 1842.

required to do—and you shall cause it to revolve continually, and with any degree

of power you please-remembering only " DOUBLE ACTING ROTARY ENGINE

to make your cylinder large enough! COMPANY."

And for this other “simple reason :" We learn from some papers which

there are

two tendencies to move" in have been forwarded to us that a project the cylinder—the tendency of the part in is on foot for the formation of a company water to rise, and the tendency of the under the above title, for bringing into part in vacuo to fall, and “the two tenuse a “new motive power,” which is dencies being auxiliary to each other, considered to be incomparably superior to necessarily produce a continually resteam, and therefore infallibly destined to volving motion!!!supersede it every where and for every The thing is so like a joke, that it may purpose. “Mighty agent” as steam is, be difficult to persuade our readers we this is represented to be mightier still. are not joking. We describe the invenTo the application of steam there are tion, however, with strict fidelity, as we certain practical limits, but this new find it described in the printed papers power is a power which“ be carried of the projected Company now before us. to any extent." The cost, too, is not The inventor and his friends then must simply less than that of steam-it is have deceived themselves ? One would "infinitely less.” People may send their in charity think so; but if they have, it is present steam engines to the marine not at least without sufficient pretence of store shops, and obtain as much for them ability to judge rightly, and without a great at old metal prices, as will suffice to display of pains to go on sure grounds. build them “infinitely" better engines on

The inventor is a Count de Predaval," this new power plan. “ The sale of “who styles hiv:self Engineer in the the rejected metallic parts" is to defray Service of his Imperial Majesty the Em"Dearly" all expenses of every kind, both peror of Austria;" and the Count, as a present and future. For, once erected, good and respectable engineer worthy of an engine on this new plan is to cost no such distinguished patronage would do, thing, or next to nothing; “no fuel, of has been careful not to submit his inven


it with

tion to the public till " after the strictest the most-if not literally the most-nonexperimental investigation has perfectly sensical and visionary of its class. proved its merits." Nay more,

It may be asked, why, if it be so foolish à view to obtain the corroborative evi a thing, we put ourselves to the trouble of dence of scientific men on his invention, this public exposure of it? We will tell it was submitted to several eminent en our readers why. Had the scheme been gineers ;" and a report of one of them" left to depend on its own merits, or even is given at length, which we are told on the authority of Mr. Edward Lomax

vouches for the excellence and appli " eminent" as that individual may be cability of the principle of the inven --for acceptance with the public, we tion," as in sooth it does. Who the other should not have thought of saying a word

eminent engineers" were, and what about it, feeling, as we should have done, they said of it we are not told. The well assured, that it could dupe nobody. Count, probably, thought that after But at the head of the “Prospectus " one of them," and he, no doubt, the there are the names of a number of permost eminent of the lot, had said his say sons paraded, as constituting a “ Provito such capital purpose, there was no sional Committee" for the management need of further testimony... Would any of this projected "Double-acting Rotary one, after quoting a Wellington on a Engine Company;" and among these there point of military skill

, think of calling is one name which, if it were placed there to witness either a Colonel Toby or Cor with the consent of the owner, would of poral Trim? But who is this selected itself command for the plan the confiit one"—the most eminent among the dence and contributions of thousands. It eminent—the Count de Predaval's Wel. is the name of one of our most learned lington of engineers ? The Report is Professors—of a gentleman of real and signed “Edward Lomax," and dated deserved eminerce for his scientific ac. from “2, Queen-square, St. James's quirements, and scarcely more distinpark.” We must candidly own that we guished for academic lore than for never heard of the name of " Edward practical wisdom, strength of judgment, Lomax" before, far less of the engineer and keenness of discrimination. Who ing eminence attached to it. We live knowing any thing of Professor de Morout of the world, however--the Count de gan, would think of asking whether it was Predaval in it, (not without some dark a piece of moonshine or humbug to which intent, we fear, to make of it “ his he had given the sanction of his name? oyster ;") and the Count de Predaval Or who, with money to spare, would hesi. says

1. Mr. Edward Lomax, of 2, tate much about paying down a few pounds Queen-square, St. James's-park," is to be one of "the first hundred " to share engineer,” and an

eminent" one, with the worthy Professor in the golden too ; and the Count de Predaval is him harvest of which M. the Count de Preself an "engineer," and " in the service daval offers to make them partakers, and of His Imperial Majesty the Emperor of in the liberal premium " which the said Austria," &c. &c. &c.

“first hundred " are to have into the barDo not all these things, then, satisfy us? gain, for benefiting themselves? Here it We must in sober seriousness say, they is the danger lies : here our reason for do not. We have no respect for bidding all and sundry-beware!

We perimental investigations which prove have the authority of Professor de Morimpossibilities—things which could never gan himself for stating that he never have been proved; and must doubt the heard of this “Double-acting Rotary mechanical knowledge and ability — if Engine Company," till he saw his name we may not the titles and the “emi at the head of the Prospectus; that te nence" – of those who “ vouch" for knows nothing whatever of the scheme, them. We protest that we never, in all or of its inventor, or of any of his assoour experience, met with any thing more ciates ; and that he utterly repudiates all ridiculous than the pretensions contained connexion with them and it, We think in this “Prospectus" of the Count de our readers will agree with us, that this Predaval ; nor any thing more elaborately looks like something more than being selfabsurd than the "corroborative " Report deceived. People do not commonly use of his friend, the Wellington of engineers, the names of other people, without their “ Edward Lomax." The scheme is a knowledge or authority, for any other pur. veritable perpetual motion, and one of pose than that of wilfully deceiving others.



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