EFFECTIVE POWER OF STEAM ENGINES. body, and most probably produced by the friction incident to life. Bacon says, that "heat and cold are nature's two hands, whereby she chiefly worketh," and if we really examine deeply, I don't think we can find any power independent of them. One simple law appears to me to carry on all the wonderful works of the Almighty, and that law to consist in the concentration and diffusion of a fluid which, in two different states, occupies all that which is commonly called space. From the chemist, the electrician, the metal refiner, the glass manufacturer, the magnetiser of the needle, and from how many others, may I not hope for a deep investigation of a theory of such very great importance to the Arts. The astronomer and physician will also find it well worthy of their deepest consideration. It may involve a very interesting question on the subject of tides. But I am unwilling further to intrude on your readers. And remain, Yours, &c., 723 the net pressure above the atmosphere-a most material difference. I do not profess to understand the third and fourth elements in Indicus's formula. The deduction of 11.5 would seem, from its amount, to be the pressure of the atmosphere: but why it should be applied to that which is already net pressure, or why it should be multiplied by the fraction 4, passes my comprehension. I shall be really obliged by the explanation which no doubt accompanies the formula in the last edition of Tredgold. For the sake of clearness I shall place the two formulæ in juxta position; the first be. ing that used by me, wherein the value of is the gross pressure in boiler; the second, that given by Indicus, wherein the value of o is the net pressure, or 66 excess in boiler above atmospheric pressure.” x.536-11.55 × a2 × v. May 12, 1849. EFFECTIVE POWER OF STEAM ENGINES. Sir,-As is often the case, the discussion between "Indicus" and myself has assumed a collateral interest, distinct from the origi`nal question, and of far more importance; being neither more nor less than the correct method of calculating the effective power of steam engines. The rule quoted by "Indicus" in your last week's number from the latest edition of Tredgold, differs so widely from that made use of by me; that it is very desirable publicity should be given, through your Magazine, to the data upon which it is based; for the benefit of such of your read ́ers as, like me, may not have access to the work itself. In the first place, it is necessary that I should satisfy "Indicus" as to my authority for the rule used by me. It is true I did not take it from any edition of Tredgold itself, but I found it in " Galloway's History of the Steam Engine," pp. 450, 462, where it is professedly quoted in Tredgold's own words. I may truly say, that the formula given by "Indicus" is quite as inexplicable to me, as The states mine to have been to him: the allowance for friction, &c. is nearly the same in both, the difference between the decimals 66 6," and "536," being the additional allowance of Tredgold for using steam expansively; but the great discrepancy is, that I apply this fraction to the gross pressure in the boiler; whereas, "Indicus" applies it to NOTES AND NOTICES. Frauds in Soap.-With regard to silica and clay soap the experiments which have been hitherto made are not sufficiently numerous to give the requisite information; but as neither the silica nor the clay contributes anything to the detergent qualities of the soap, but merely increase its weight, all such additions ought to be prohibited by Government. Suppose a pound of good soap to cost 6d., and that another soap, containing 20 per cent, of silica or clay, is sold at 42d., the two will be exactly the same value, for four pounds of the good soap will go as far as five pounds of the adulterated soap. If the manufacturer charges 5d. for the pound of the adulterated article, he overreaches his customers to the extent of a farthing per pound. If this apparent cheapness have a tendency to increase the sale of soap, it operates as a premium to induce manufacturers in general to adulterate the article. The great extent to which the trade of Great Britain has reached was originally founded on the goodness of the articles manufactured; the present rage for cheapness has an universal tendency to adulterate every article exposed for sale; and, unless it is counteracted by a vigilant government, it must terminate in the destruction of the foreign trade of the country. The soap made for exportation is always of inferior quality; hence the monopoly of the French soap-makers, who supply Italy, Spain, and South America with all the soap required by those extensive countries. If silica soap be permitted to be inade, it ought to be charged according to its specific gravity, allowing it to contain 20 per cent of silica, as the maker supposes it to do. Hence its specific gravity in the liquid state ought to be 1.3191. Hence a pound of it will have the bulk of 21.016 cubic inches; or it ought to pay one-fourth more duty than common yellow soap. In what is called clay soap the clay is not at all combined with the alkali, no soap is formed with it; and its action is merely mechanical; in fact it diminishes the power of the soap with which it is mixed in proportion to the quantity. The motives for mixing clay with soap are too obvious and too well understood to require any comment.-Report of Commissioners of Excise, Steam Pressure Indicator and Safely Valve-At the last meeting of the Society of Arts the gold Isis medal was awarded to Mr. Robert M'Ewen, for a mercurial gauge which answers the double purpose of an indicator of steam-pressure and a safety-valve for engine boilers. The novelty of the invention consists in the employment of a mercurial tube as a safevent for the steam, these tubes having hitherto been used only as indicators of pressure, and of a length sufficient to allow the steam to acquire a dangerons degree of pressure without giving any other notice of the fact than that which may be observed by the eye. As the action of Mr. M'Ewen's safety-valve depends on a purely physical principle, viz.: the opposition of the elastic force of steam to the static pressure of mercury without a mechanical obstruction of any kind, it affords a free vent for the steam when its pressure exceeds the limit, corresponding to the length to which the tubes are adjusted, according to the strength of the boiler. New Escapement.-At the meeting of the Royal Society on the 5th instant, a description was read of a new escapement invented by the late Captain Kater, communicated by his son Edward Kater, Esq. The great object aimed at by Captain Kater in the construction of the escapement of a chronometer is to communicate equal impulses to the pendulun through some principle perfect in itself, and not dependent for its success on superior execution. In the escapement invented by him, the pendulum merely raises a weight through an increased space in its descent. It neither unlocks a detent nor has anything to do with the train; and as the weight raised, and the spaces described, are constant quantities, this escapement is in the strict meaning of the term, one of equal impulse. Messrs. Fourdrinier.-We are glad to observe that parliament have at length, on the recommendation of government voted the sum of 7,000l. to the Messrs. Fourdrinier for their important improvements in machine-paper making. Never was a national reward more justly merited. Electro-Magnetic Nomenclature.- Much difficulty arises in naming the two poles of a battery; they are called the positive end and the negative end, the anode and the kathode, the platinode and zincode; now as each pole of a simple battery becomes reversed it the battery is doubled, Mr. Smee proposes (Philosophical Magazine, for May) to name the two ends from the oxygen and hydrogen, since it has been shown that the galvanic current owes its power of decomposing many substances entirely to these gases. The names which are proposed are the oxode, at which oxygen is evolved, and the hydrogode, where the hydrogen is given off. Similar Affinities of Different Substances.-In mineral chemistry this singular observation has been made, that chlorine may be substituted for manganese in permanganic acid, without the form of the salts produced by this acid being changed. Nevertheless, it is hardly possible to find two bodies between which there exists a greater difference in chemical properties than there is between chlorine and manganese. An experiment of this kind is not to be discussed; we must leave to the fact all its value and say, chlorine and manganese may take each other's place without the nature of the combination being altered by it. From that time I do not see why this manner of acting should be considered as impossible for other bodies, such, for example, as chlorine and hydrogen. The interpretation of these phenomena, such as it has been laid down by M. Dumas, appears to me to give the key to most of the phenomena of organic chemistry. Without denying that bodies take each other's places in a great number of combinations, according to their place in the electric order, I think from the manner of acting of organic combinations, we should draw this conclusion: that a reciprocal substitution of simple or compound bodies acting in the manner of isomorphous bodies, should be considered as a true law of nature. This substitution may take place between bodies which neither have the same form nor are analagous in composition. It depends exclusively on the chemical force which we call affinity. -Leibeg. Glass Weaving.-Few are aware that glass is now woven with silk, although its brittle nature would appear to render such a method of manufacturing it impossible. The fact, however, is indisputable, the new material being substituted for gold and silver thread, than either of which it is more durable, possessing besides the advantage of never tarnishing. What is technically called the warp, that is, the long way of any loom-manufactured article, is composed of silk, which forms the body and ground work, on which the pattern in glass appears as the weft or cross work. The requisite flexibility of glass thread for manufacturing purposes is to be ascribed to its extreme fineness, as not less than 50 or 60 of the original threads (produeed by steam-engine power) are required to form one thread for the loom. The process is slow, as not more than a yard can be manufactured in 12 hours. The work, however, is extremely beautiful, and comparatively cheap, inasmuch as no similar stuff where bullion is really introduced can be purchased for anything like the price at which this is sold; added to this, it is, as far as the glass is concerned, imperishable. Some admirable specimens of the manufactured article may be seen at the Polytechnic Institution, Regent Street, especially two patterns of silver on a blue and red ground, and another of gold on crimson. The jacquardloom by which it is woven may also be seen at the same establishment,-Times. New Water Works.-The Southwark Company have purchased some land at Battersea, where it is intended to construct reservoirs for receiving the Thames water taken from that part, and allowing it to settle; and also to erect steam-engines for the supply of the district. The works have been commenced, and it is expected that they will be completed by the end of the present year, or by the spring of 1841. Coach Wheel Retarder.-Full trial has now been made of the valuable invention of R. W. Jearrað, Jun., Esq., for retarding (not locking) the wheels of carriages when going down hill. Mr. Dangerfield, coach proprietor, having had it applied first to one of his Southampton coaches, and afterwards to the Shrewsbury coach, and in both cases with the greatest success. The principle of the invention is pressure, so applied to the nave of the wheel as to retard its motion, or at will of the coachman stop it altogether. The advantages of the invention are, that the power may be applied at the discretion of the coachman, so that he might take his coach down a steep hill without allowing his horses to be pressed upon at all. This invention reflects great credit upon Mr. Jearrad, and we hope it will be extensively applied to our four-wheeled carriages, for it will contribute greatly to the safety of the public. -Cheltenham Journat, LONDON: Printed and Published for the Proprietor, by W. A. Robertson, at the Mechanics' Magazine Office, No. 166, Fleet-street.-Sold by W. & A. Galignani, Rue Vivienne, Paris, MR. J. G. SHUTTLEWORTH'S IMPROVE. The improvements comprehended under the present patent, consist, according to the statement of the patentee, "in applying two rows of cogs and guide or steadying pins to an extension or elongation of that part of the piston-rod of a steam or other such engine whichwhen the piston is down (if the cylinder be placed vertically) is above the top of the cylinder, and causing those two rows of cogs to act alternately upon segments of cogged wheels, in such manner as to cause a continuous rotation of the axes of the segments, which axes may thereby be used as driving shafts for machinery without the intervention of any cranked shaft." Fig. 1, on our front page, represents a front elevation of the piston of a steam-engine (at half-stroke) with Mr. Shuttleworth's patented additions. The piston-rod works as usual through a stuffing-box in the top of the cylinder. The part of the piston-rod C, which is furnished with cogs, never goes through the stuffing-box, but in all positions of the piston is above it; D, is a channel or groove in the piston-rod, working over a dovetailed feather on the cross-bar E, to steady it; F. G are two segments of cogged wheels on the shafts of which are fixed the toothed-gear wheels H and I, taking into the carrier or communication toothedwheel, K. When the piston-rod rises, it carries with it the segment F, and when it descends it carries with it the segment G, and as whichever segment is acted upon by the piston-rod causes, by means of the communication-wheel K, and the two gear-wheels H and I, the opposite segment to be brought round, a continuous rotary motion in one direction is given to each of the axes or shafts of the segments and toothed-wheels. In order more effectually to secure the release of one segment, and the biting or taking in at the same instant of the other, there is a contrivance L (see figure 2) on the centre or communication wheel K. This contrivance consists of a raised groove or tappet M, fixed in the face of the wheel K, which takes a boss or steadying pin pro jecting from the piston rod at P, and thus secures the ascent of the rod sufficiently high in one case to fully release the segment F, and catch the segment G, and the descent of the rod sufficiently low in the other case to secure the full release of the segment F, and perfect catch of the segment G. A fly-wheel which may be placed on any of the three axes, will also add its influence to effect this object and steady the motion of the engine. The claim of the patentee is to "the application of cogged gear and steadying pins, such as before described, directly to the piston rod of a steam engine for the purpose of obtaining a rotary motion for the driving shaft from the rectilineal motion of the piston-rod, and without the intervention of a cranked shaft." ON THE CONSTRUCTION OF MALT- Sir,-Agreeably to the intimation contained in the last paragraph of my letter, on the subject of malting and the evils of the present system of fiscal regulation, which you did me the favour to insert in the 872 number of your valuable work, I beg leave to present to those of your readers, who may feel an interest in the subject, some observations on the construction of malthouses and breweries. Having endeavoured in the letter referred to, to prove that the process of malting, is but a very imperfect imitative attempt to copy the process of germination to a limited extent, as conducted by Nature in the field, and that but for fiscal restrictions, the maltster possessing a competent knowledge of the system, might copy her method much more closely and effectively, and thereby furnish to the brewer a much superior malt than he can at present command, it now devolves on me to endeavour to show, that in the construction of the malthouse (over which the executive exercise no prejudicial control) an architect should be employed, who in addition to the requisite qualifications of his profession, should possess a comprehensive knowledge of the subject of germination, as practised both in the field and malthouse, in order that he may render the building the best adapted to enable the ON THE CONSTRUCTION OF MALT-HOUSES AND BREWERIES. maltster to assimilate his process as near to that of Nature's, as circumstances and Excise restrictions will permit. The principal features in the arrange ment of construction and fitting up of the malthouse, which require architectural and mechanical attention, are the allowance of a sufficient space for the manufacture of a definite quantity of malt under every varying circumstance a suitable construction and fitting up of the cistern-a sufficient space for the grain in the couch-the working floors to be formed of a proper material-the kiln to be constructed on scientific principles, and to be of sufficient dimensions-provision made for the admission of atmospheric air and the emission of carbonic acid gas, without the access of light, except when indispensably needed-an ample supply of good water, and the adoption of means to render it of suitable temperature-and the supply of barley and mal: stores, well situated, protected from vermin, dry and warm. Upon each of these heads, much useful and valuable information might be furnished, but as it would occupy too much of the space of your columns, and as the impartation does not fall within the purport of this communication, I must beg leave to refer those who wish to acquire it, to my Cyclopædia for the use of Maltsters, Brewers, &c., or to my practical Treatise on Malting and Brewing for the full particulars. The brewery may be properly termed a manufactory, in which the chemical process of manufacture of beer of various sorts,strengths,and qualities is conducted. But I am fully aware that the term chemical, is so intimately blended in the minds of many with an imaginary use of drugs, that the bare mention of it, is sufficient to awaken and alarm all their fears and prejudices, and to close at once all the avenues to their minds, if an attempt is made to introduce the subject of brewing under such an obnoxious title as a chemical process. But the truth must not be scared or deterred from the use of such a term, and this bugbear to many a timid and prejudicial mind, must be divested of its imaginary terrors, before the affected can ever attain to a sound and comprehensive theoretical knowledge of the subject of brewing, or a correct and advantageous practical process. 727 The use of the terms trituration, agitation, digestion, filtration, decoction, cation, by the chemists, and synonymous refrigeration, decomposition, and clarifiwith the terms grinding or crushing, mashing, solution, abstraction, boiling, cooling, fermentation, and fining, used by the brewer, are quite sufficient to identify the manipulations of both, as alike chemical; and hence the necessity that the brewer should so construe it, and not deem it merely mechanical,-hence the importance of his being induced to seek for a scientific knowledge of his process, and thereby learn the necessity for, and the mode of, effecting the architectural arup of his brewery, adapted and subserrangements and the mechanical fittings vient to all the requisite conditions of a chemical laboratory. The absence of this view, and requisite knowledge of the subject, in the proprietor, the architect, the builder, the engineer, and the utensil manufacturer, are strikingly indicated in the numerous heterogeneous designs for breweries, and their dissimilar erection throughout the kingdom; and much superfluous building, number and size of utensils, disorder and inconvenience of their arrangement, and a most wasteful extent of premises, are characteristic of the majority. Conciseness and simplicity should pervade every department both of the malthouse and brewery; instead of which elaborate incongruity may be said to universally prevail, and the greatest sticklers in declaration for the former, are generally the most obstinate perpetuators of the latter; because that which they comprehend by habitual use they pronounce as simple and plain, however inconsistent, inexplicable and erroneous it may appear to others; and when any real simplification and decided improvement of their premises or system of manufacture is suggested to them, they unhesitatingly and vehemently exclaim against innovations, scheming, and complexity, and not only turn a deaf ear to every explanation, illustration, and proof, but treat the offers of improvement either with silent contempt or insulting derision. Maltsters and brewers are not (as a rule) literary or scientific men; the greatest portion of their time is occupied in the industrious pursuit of wealth and its expenditure in pleasure when at |