were required, from the simple fact, that the only witnesses who were subjected to what may be termed a cross-examination, were precisely those who had the temerity to express an opinion in favour of our native workmen,-amongst whom the editor of the Mechanics' Magazine came in for the greatest share, although his cross-examiners certainly "took nothing by their motion." It is impossible to read without amusement the answers returned by this witness to some of the puzzling questions propounded by the wiseacres of the Committee,-to observe without a smile the manner in which he makes his replies tell to the confusion of his pragmatical questioners. For instance, when some M.P. is determined to make it appear that the public call for none but the most classical of designs, while the workmen persist in thrusting inferior designs down their throats, sorely against their will, how completely is he put down by the quiet observation, "there is a pattern which was a long time in very general use for table-service, called the willow pattern '-there is nothing very classical in that!" Again, how pleasantly are the Committee rebuked for their disposition, to run down our homebred taste to the exaltation of every nation on the Continent," by the remark that " very much of the bad taste of this country has been owing to the circulation of wretched prints all over the country, and still more wretched stucco. images," and that "this inundation of execrable taste has not proceeded from native artists, but from Italians !" Oh! for a Cruikshank to have sketched the elongated physiognomy of the Honourable Member at this truly home-blow! Shocking, indeed, it must have been to the feelings of the whole Committee to be reminded thus unceremoniously that the public taste is now too improved to put up with the trash these foreigners were guilty of perpetrating, but required something far superior,-in the shape of casts from the works of Chantrey, an English professor of the "highest branches of poetical design," and of Thom, one of the very class of mechanics whose inferiority in the arts of design is so deeply to be deplored!

A good sifting cross-examination might have been employed to better effect in a far different quarter. Mr. Donaldson, the architect, gave a first-rate opening

for any member of the Committee-had there been any,-with a British feeling, to "show up " the true value of his evidence. This gentleman, by way of illustrating his position as to the cheapness of art in France, instanced his own work on doorways, the plates to which would have cost him four guineas each in England, whereas he "sent his drawings to Paris, and had estimates from four French engravers,-put the work into the hands of the best of these,-a man who is second to none in Europe in his art,-paid the expense of the carriage of the plates to England, the duty of 30 per cent., and various incidental expenses, and the whole cost did not exceed two guineas! Now it appears that Mr. Donaldson had just before introduced to the Committee the "Vorbilder fur Fabrikanter und Handwerker," of which we hear so much in their Report. What, then, if our imaginary cross-examiner, after a due time spent in admiration of the most elaborate of all the plates, had begged of Mr. Donaldson to give him the name of the engraver. Would he not have felt a little embarrassed as he answered "WILSON LOWRY?" Suppose the same process repeated with a second, a third, a fourth, the masterpieces of the whole work,-would Mr. Donaldson have been able to suppress a blush as hestammered forth the names of TURRELL, ROFFE, and MOSES, all well known as first-rate English engravers? Terribly would he have been perplexed as the annoying questions poured in upon him. How was it that Professor Beuth entrusted none of his elaborate embellishments to the Frenchman," who is second to none in Europe in his art ?" How came he to pass him by, with all his cheapness, and send his work to the high-priced English engravers, paying to boot the expense of the carriage of the plates to Germany, the duty, and the various incidental expenses connected with their being executed in London and transmitted to Germany?" Simply, of course, because Mr. Donaldson's Parisian engraver could not come nigh our countrymen in the practice of the highest branches of the art. Mr. Donaldson's doorway plates may have been done cheaply, but they can hardly have been done well, as well as they would have been here. To suppose otherwise, is to suppose Professor Beuth a natural-born

fool, and the Prussian government a sad waster of its cash. Nor can the Germans in general be much wiser than the Professor, for with them a book" mit Englischen stablistichen" is considered a very superior affair. The Russians, too, must be a stupid set, when they send to" dear old England" if they want a first-rate embellishment, instead of putting in requisition the talents of the half-price Frenchman," who is second to none in Europe in his art." But what are we to say to the French themselves, who, in spite of their possessing this cheap firstrate, -"second to none in Europe in his art," not only invite English second-rate engravers to Paris (who there suddenly find themselves promoted to the front rank of the profession), but actually encounter the higher charges of our artists, and all the expensive etcetera, whenever they wish to bring out a book or a print in the very first style of art. It is so notorious that even Mr. Donaldson must have allowed it, had it been put home to him, that any Parisian engraving of unusual excellence will be found, on examination, to have an English name in the corner.

This letter has already extended to so great a length, that, for fear of trespassing too long on your and your readers' patience, I hasten to conclude by subscribing myself,

Sir, yours most respectfully,

London, Jan. 17, 1827.

a

Fig. 1.

13 in.

Fig. 2.

Fig. 3.

H.

IMPROVED TIMBER-RAILWAY BASE, AND

SADDLE-RAIL.

Sir, I beg to offer my ideas of Mr. Vignoles' project for longitudinal timbers for the upper works of railways. It appears, in my view, that the scantling is too slight, and that the material composing the rail is not disposed to produce the greatest strength.

Suppose the Memel timber to be sawn diagonally, four pieces will be the result, as before; but instead of 9 inches bearing, they will have 13 inches, and instead of a depth of 4 inches, they will be 6 inches; and in the shape, very nearly approaching to that which has been demonstrated to be the strongest, with a minimum of materials. The following hasty sketch will explain.

41

Fig 1 shows the Memel timber, with the saw-kerfs for cutting four. Fig. 2, the timber in position, surmounted with the rail cast saddle-ways, presumed to contain 48lbs. per yard.

In p. 259, Mr. Vignoles states that if an equal economy in sawing up of the timber can be otherwise obtained, wrought-iron rods may be used to keep the track in gauge; of course, they will be applicable here.

Figure 3 shows the practicability of getting eight timbers out of the baulk fig. 1, by cutting again from a to the centre. I do not venture to say this will be strong

enough, but as the bearing and the depth is the same as proposed by Mr. Vignoles, I have shown it on the score of economy, and think it will be equally applicable as his on solid, or unmade ground. I am, Sir, yours truly,

W. THOROLD. C. E.

Norwich, Jan. 14, 1837.

ACTION OF THE ATMOSPHERE IN BOILING WATER.

Sir, I cannot refrain from troubling you with a few remarks on that collection of errors which appears in a recent number, under the title of "On the Action of the Atmosphere," and which bears the signature of " W." As the whole article is composed of details of experiments, explained on the most miraculous principles, for the purpose of supporting the theory which is advanced in the first sentence, we cannot do better than examine the experiments, and show the absurdity of the explanations, in the order in which "W." has arranged them.

In the first place, "W." asks, Is not boiling "caused by a current of air, which enters through the bottom of the vessel, rises up through the water, and thereby causes the bubbling?" &c. How "W." could imagine that air would penetrate "through" a piece of metal was to me a matter of surprise, until I found it accounted for most readily in another part of his remarks. "The heat of the fire," he observes, "rarefies the air, expands the metal of the vessel, and by these means the air appears to be enabled to penetrate the metal!" But "W." will find that "these means" are not adequate to produce the effect which he ascribes to them; for if he will trouble himself to procure a metallic vessel, and after heating it much hotter than the temperature of boiling water (and consequently causing the metal to expand inuch more), expose it by means of a condensing syringe to a very great pressure, and not merely to a current of hot air, he will find that after exposing it to these additional "means," not a particle of air will penetrate it. Thus we see that boiling cannot be caused by the bubbling up of air, which has “ penetrated" the metal; and if "W." still maintains that it is caused by "currents

of air," he must show, in a more satisfactory manner, how the air arrives at the bottom of the vessel.

66

He next asks, "Does not the light coloured matter, which is called steam, consist of particles of water thrown up and carried off from the surface by the air, as it rushes through the boiling water?" Steam is not light coloured matter," but is perfectly invisible, and although it consists of particles of water, the particles are not torn asunder by the rushing" of air through the water, as "W." supposes them to be, but stand at the great distance from each other, in which they are found in steam, by virtue of heat, and without any connexion whatever with the air.

"W." next directs attention to the phenomena which present themselves, in the passing of cold water to the boiling state; he imagines that the small bubbles which appear on the sides of a vessel of water, when becoming warm, are the first appearances of boiling. Truly, these small bubbles are portions of air; but they are not produced on the sides of a vessel from "currents of air" which "penetrate it," but have first been absorbed from the atmosphere, by the water being exposed to it; and if "W." will take a portion of water, and expose it under the exhausted receiver of an air-pump, he will observe that these bubbles of air will rise from it without the assistance of beat, and that the water thus freed from air, will no longer exhibit these small bubbles on his applying heat to it.

Another argument which "W." uses to support his theory is, that "if a tin vessel containing water be partly immersed in a vessel of boiling water, the water in the tin vessel may be raised to a boiling heat, but will not boil," because, as he supposes, the air is excluded by the boiling water which surrounds the tin vessel. Here he first tells us, that the boiling of the water in the large vessel is occasioned by the "currents of air" which "penetrate the bottom" of it, and rise to the top; but he says that the water of the small vessel cannot boil, because the air has no access to it. Pray, what becomes of the "currents of air" which rise from the bottom of the large vessel in which it is immersed? In rising they must inevitably

strike against the bottom of this tin vessel and as metal, at the temperature of boiling water, is readily penetrated by air, according to "W.", why do not the currents of air pass straight on through the tin vessel, and cause boiling in both portions of water? Perhaps "W." will say, that the currents of air are not presented to the bottom of the tin vessel in a favourable manner, and that, from the density of the water, they rise through it so quickly, as to escape without having had an opportunity of passing through the tin vessel; but "W." may make the tin vessel with a concave bottom, and then what he calls the 66 currents of air" will collect under the tin vessel, and will be pressed against its bottom by several inches of water: and if currents of hot air pressed against the sides of a vessel, merely by the superior density of the air surrounding them, will penetrate the vessel, surely air of the same temperature, pressed against a vessel by several inches of water, ought to pass through it much more readily; and thus, according to "W.'s" own theory, the water in the tin vessel ought to boil more rapidly than that in the vessel in which it is immersed. But "W." says it is not so, and, consequently, this one fact which he adduces to support amply his theory, is sufficient for its complete destruction.

We are next informed, that if we invert a tumbler filled with water in the vessel in which the water is boiling, that the bubbles of air will ascend into the tumbler, and by displacing the water, will fill it with stean, or what" W." calls "currents of air." Now, the science of pneumatics teaches us that air is possessed of the common properties of matter, and among others of indestructability and of impenetrability, or the property of not allowing another species of matter to occupy the same portion of space as that in which it exists, until it be removed. From this we may infer, without any great stretch of our reasoning powers, that the air in the tumbler, if we did not cause it to be removed, would remain there an indefinite length of time. But "W.'s" air is not common air; for let the water, over which it is confined, cool a little below the boiling point, and this air which was collected in the tumbler will disappear, not one jot of it will be

left in the glass. Now, if it really be air which was collected in the tumbler, let "W." show where it has gone to, or how escaped.

I think from these remarks, "W." will perceive that boiling is not caused by currents of air penetrating the hottom of the vessel; and if, for argument's sake, we allow that it were, he will see this inadequate for the explanation of the phenomena.

I cannot conceive that "W." made his remarks on boiling in ignorance of the real nature of the process, for he certainly must have observed facts that were in direct opposition to his theory. Did he never see water boiled under the exhausted receiver of an air-pump, and that much more rapidly, and at a lower temperature, than when exposed to the atmosphere? Or, is he not aware that ether will boil at an ordinary temperature, when placed in a vacuum ; and that every substance is evaporated more readily when protected from the atmosphere, than when exposed to it? If he has seen these phenomena, he must immediately perceive that currents of air," rather than being the sole cause of this phenomena, are positively prejudicial to it; and if he has neither seen nor read of these experiments, I think it would have been prudent of him, before publishing such inconsistencies, to have consulted some treatise either on heat or on air; for after so doing, he cer tainly would have abandoned such "vain reasoning all, and false philosophy."

The bubbling, &c., which we call "boiling," is occasioned by the rising of steam from the bottom of the vessel, in which the boiling water is contained. "W." will find that on first applying heat to water a motion will take place in it; the water at the bottom of the vessel becomes expanded by the heat, and as it is then of less specific gravity than that at the top of the vessel, it immediately rises and displaces the upper portion, which descends to the bottom of the vessel, then becomes heated, and in its turn rises: and thus a continual circulation of the water takes place during the time in which it is becoming hot, until it arrives at about 212 degrees Fah., when the phenomenon of boiling commences. W." is, perhaps, aware that all substances may, by the application of heat, be made to resign the solid

form, and to appear in the state of vapour; and that the temperature at which a substance passes into this state, is, under ordinary circumstances, fixed and unalterable. Thus he will find that he cannot cause the water, with which he experimented (unless it be impure or subject to pressure), to become of higher temperature than that above mentioned: as. on applying heat to it after it has arrived at that temperature, it will only cause it to boil, the heat being expanded in the form of steam, while the water will remain of precisely the same temperature. I presume from this, "W." will perceive the process of ebullition to be the rapid forination and escape of steam, instead of "currents of air." I will now attempt to explain to "W." the reason why a vessel of water, on being immersed in boiling water, does not also pass into the boiling state. Although boiling water is of the temperature 212 deg. Fah., yet it requires a greater heat than that to make it boil. The reason of this is, heat is an essential ingredient in the composition of steam. If we take a pint of water of the temperature of 212 deg. Fah, (the boiling point), we shall find that it requires a very great quantity of heat to convert that water into steam of the same temperature. Hence, the heat we apply is absorbed by the weter, and becomes one of the component parts of the steam, where it lies dormant so long as the vapour is kept from cooling; but inmediately it becomes lower than 212 degrees F., the water of the steam is condensed, and the heat which had entered into the composition of it instantly becomes apparent; and "W." will find that the heat, which the steam from the pint of water gives out in condensing, is sufficient to raise very much more than the quantity of water from which it was produced to the boiling point. "W." will now perceive why it requires the application of a greater degree of heat than that of boiling water, to make water boil; and he will see the reason why one vessel of water does not boil on being plunged into another vessel that contains boiling water. He will perceive that it is not, as he supposed, because the air could not have access to it; for if he had plunged the tin vessel into boiling oil or quicksilver, either of which would have excluded the air as effectually as water,

ENGRAVING MEDALS BY MACHINERY.

A petition was lately presented to the House of Commons from Mr. Tilt, the bookseller, of Fleet-street, which sets forth, "That a machine has been invented, and is now brought to perfection, by which the likeness of any object, represented in relief, can be accurately transferred to a plane surface on any proposed scale, so as to affect the eye in precisely the same manner as the original— That by the use of this invention the object which your petitioner proposes [the publication of engravings of all the medals in the British Museum] could be effected with the most minute precision, at a cheaper rate, and in a manner far more perfect than if the ordinary methods only were employed-That eight medals on an averaverage, with their reverses, could be included in one plate, were the size of imperial quarto adopted for the publication, which would thus require 400 plates for its completion-[there being 3200 in the British Museum collection]-the whole series could be comprised in five volumes, and produced without difficulty in the space of five years-That your petitioner submits that the publication in question, which relates to a class of national antiquities, now open but to a few persons, and which throws so much light upon the history of the country, must be regarded as an important national work, and that many countries of Europe, as in France, Italy, and Denmark, the same has been already produced at the expense of their respective governments." The House referred this petition to the committee on the British Museum, who devoted several sittings to the exclusive consideration of the subject matter of it, but at last contented themselves with simply reporting to the House the the "Evidence" of which the substance follows.

Mr. Charles Tilt

Thinks that the publication of the historical medals in the British Museum collection, engraved by M. Collas' machine, would be of great interest, and would have a consider