to keep them in a vertical position. A pipe passes into the cylinder through which the feed water to be heated is forced by means of a pump. This pipe terminates in the receptacle or rose, the lower sur face of which is perforated with holes like a colander, The cylinder has a top of a conical form (perforated with a number of holes), from the middle of which proceeds another pipe, which terminates in the cock or valve; b, b, another cylinder, which slides on the cylinder A; it is furnished with a cover, and the steam is prevented from escaping by packing. To render the movement of the cylinder b, b, as easy as possible, it is balanced, or as nearly as may be, by means of pulleys and weights; a light rod attached to the cover of the cylinder b carries two pins or studs, one of which opens the cock or valve when the cylinder b has risen to its extent, and another one which closes the cock or valve when the cylinder is at its lowest point. A spring is used to prevent concussion of the cylinder rising suddenly, or the spring may be made also to act as a counterpoise, and so obviate the necessity of using the weights; c, a pipe, which communicates with the feed pump. The operation of the apparatus is as follows:-The engine or other steam apparatus being at work, a portion of the steam which is evacuated from it forces its way through the pipe a into the interior of the cylinder; this compresses to some extent the air contained in it, and raises the cylinder to the position shown in the figs. In this position the valve or cock is opened by the rod, and the air passes into the atmosphere, and the cylinders become filled with steam, which consequently heats the coils of wire to its own temperature. In the meantime water has been ejected into the cylinder through the central pipe, and falls amongst the heated coils and steam by which they are commingled together; the water becomes heated and then falls through the holes in the plate to the bottom of the cylinder, from whence it is drawn through the pipe c by the feed pump and forced into the boiler. Fig. 3 represents a modification of the apparatus, Fig. which is more particularly applicable in cases where the steam is evacuated under a more or less amount of pressure. A third cylinder, e, is placed below, in which a piston works, provided with a piston rod, cross-head, and two side rods connected with the cross-head. The side rods are connected at their upper ends to the snugs on the cylinder, so that when the cylinder rises the piston rises with it, and the air in the cylinder e is proportionally compressed, and thus acts as a spring or weight; f is an air vessel connected with the cylinder by means of the pipe, having a safety valve and a cock, by means of which the vessel can be supplied with air as may be required. Instead of air, steam from the boiler may be used in the cylinder e. The object of this apparatus is to adjust the pressure on the piston, and consequently the pressure on the steam in the cylinder, to any degree of nicety which may be required. The operation of this apparatus is similar to that shown in figs. 1 and 2, with the exception that it is better adapted for cases in which the steam is evacuated or discharged from the engine or steam apparatus under considerable pressure, and consequently greater heat than in the former case. STEWART'S MOULDS FOR CASTING. MR. D. Y. STEWART, of Glasgow, N.B., ironfounder, has just patented an improvement in moulds for casting, which has for its object the formation of moulds in such a way that a succession of castings may be taken from them, such moulds also producing more or less chilling of the castings. In applying the present invention to the core portion of moulds for such articles as pipes, it is preferred to use a collapsable core bar. This consists of two pairs of segments F, G, connected by links to a central bar in such a way that the longitudinal adjustment of this central bar in one direction causes the two narrow segments F to be drawn inwards, and the two broader ones G to follow them, the reverse adjustment causing the segments to be expanded to the required size. The Fig. 3. THE VOLUNTEER SPORRAN; OR, TOURISTS' EXCURSION BAG. : cost. its contents (which, from the flatness of form the sporran had without it at a reduction of This leaf can be detached at pleasure, and The requisites, not shown on the plates, aretowel, pair of socks, forage cap, housewife, clothes' brush, soap, tobacco bag, Alma strike-light, and writing apparatus; and, there being a distinct compartment for everything, all trouble in arrangement is avoided, and whatever may be wanted got at immediately. Sporran No. 2, which is especially recommended for Volunteer use (the other being more adapted to the requirements of the tourist), is of rifle-grey American cloth, such as used for the knapsack; but can be had of any colour suited to the clothing of the corps, either plain or ornamented, to order, with any required regimental device. It contains ammunition leaf, as already described, and toilet, smoking, and meal requisites, on a simple and reduced scale. Both sporrans are so constructed that they can, with equal regard to convenience, be suspended over the shoulder, or over the region of the pelvis, after the fashion of the Highland sporran; the peculiar advantage derivable from which is that the "pelvis," from its arched construction, being by far the strongest portion of the human body, a weight of three or four pounds thus sustained is almost inappreciable. Messrs. Charles Prater and Co., army contractors and accoutrement makers, No. 2, Charingcross, London, S. W., are the sole manufacturers of the Volunteer Sporran, which sells for 42s. for tourists, and 25s. for volunteers. Without the ammunition leaf the cost will be some three or four shillings less; and, if preferred without the goat's hair, it is supplied still cheaper. GAS ENGINEERING. A SOURCE of very great loss to gas companies is the condensation and leakage of the gas in the street mains. In some instances as much as onethird of all the gas manufactured is thus lost; and the writer believes that the average loss is not under 15 per cent., and in no case under 10 per cent., although some gas managers have stated a less quantity. This is a department which should have the engineer's careful attention, and much may be done to lessen the loss; but to bring it down to 1 per cent. is an impossibility, for a much greater loss must occur from condensation alone. The quantity and sizes of the pipes, in proportion to the amount of gas consumed, must also materially affect the amount of loss. When the towns are compact and the consumers close together, the loss will be smaller than when the consumers are scattered at a distance from each other, as often occurs in small towns. Much, however, can be accomplished to reduce the loss, by the sizes and quality of the pipes, and the way in which they are jointed. When the main pipes are too small in diameter to give an ample supply of gas, a heavy pressure must be put on at the gas-holder to force the gas quickly through the pipes. The pressure should not exceed in level towns 1 inch of a column of water; but it in some towns exceeds 4 and even 5 inches, the loss of gas increasing with the pressure. All sizes of pipes, from 14 inches upwards, should be cast vertically in dry sand moulds; pipes thus made are free from pores, and the metal is closer in the grain than when cast in green sand, and on an angle or bank: for although the latter quality of pipes will stand the test of the hydraulic press, yet there is no doubt they do allow gas to escape through the pores of the metal. It is a well-known fact, that where gas-pipes have lain for a number of years, the surrounding earth is impregnated with gas to a considerable thickness. Another cause of loss frequently arises from the pipes being made thin and light, and in some soils they are very soon corroded. This is false economy. The methods of jointing pipes generally adopted are those with spigot and faucet packed with hemp or rope yarn and lead, and spigot and faucet bored and turned joints. The latter kind, when properly made, have the advantage of being quickly laid, as the joints require only to be coated with red lead paint, and knocked home with a mallet. They make a very perfect joint. The quality of the gas is a very important matter, and requires careful attention. On the quality of the coal depends, in a great measure, the illuminating power of the gas. Cannel coal yields the largest quantity and richest quality. The price of gas should be regulated by its illuminating power. To compare the gas of one town with that of another, by the prices charged per 1,000 cubic feet, gives no true result, because the illuminating power of the one may be double that of the other. Gases are sometimes tested by comparing their specific gravities; but owing to the presence of carbonic acid or atmospheric air, this method is not a sufficient test, and the photometer test is therefore preferred, as by it the quantity of light actually yielded is measured. The meter, by which the quantity of gas used by each consumer is measured and registered, is a most important instrument. Previously to its invention in 1816, by Samuel Clegg, Esq., recently deceased, each burner was charged for according to a scale of prices, and had to be paid for whether in constant use or not. With the meter the consumer only pays for the quantity of gas that he actually consumes. This instrument has, therefore, been the means of greatly extending the use of gas. In the discussion which followed, Mr. Bartholomew stated that since iron retorts cost under £4 per ton, there was not so much need to make them of fire-clay. He maintained that the quantity of gas which escaped through the sides of fire-clay retorts would soon amount to the cost of renewing them. The cast-iron retorts used in the City and Suburban Gas Company's works did not cost more than Id. per thousand feet of gas made in them. In answer to the President, Mr. Davison said that the American ferry-boats were lighted by gas contained in a small portable dry gasometer, with India rubber sides, like a pair of bellows. He had never observed how the large vessels were lighted. Railway-cars were lighted with gas compressed into a cylinder placed underneath each carriage, from which pipes were led to the different parts of the car. Gas was found more economical than oil. The President remarked that Mr. Laidlaw had not alluded to one of the first modes of distributing gas to people in a city, by means of portable vessels into which the gas had been compressed. Mr. Laidlaw replied that these were spherical vessels of iron or copper. At present Moscow was partly lighted in that way; but it was a most inconvenient plan, as well as expensive, as a great loss resulted from condensation of the gas in the vessels. They filled large jars, and conveyed them to their customers every morning. It was oil and resin gas which was formerly used in this country for portable gas; but that was only for a short period, as it proved a complete failure. strata are at the present time being deposited along the beds of existing seas, the investigation of these questions becomes of the highest consequence, as bearing on the successful establishment of ocean telegraphy. known to become much more equable at great depths; The composition of the waters of the ocean is well and it, therefore, exercises a far less marked influence on the presence of animal life than it does at the surface. The same causes, which equalize the temperature in so remarkable a manner as the depth increases, are effective in equalizing the relative proportions of the various ingredients that enter into the composition of sea water, in all latitudes. For, whilst the surface stratum is subject to dilution with fresh the less subject ean the waters be to this influence, water, from various sources, the greater the depths, and the less can it operate in modifying the distribution of the organisms that frequent them. The temperature of the sea is materially influenced by the climatic conditions of different latitudes; and, of course, exercises a powerful effect both on the distribution and abundance of the higher orders of living beings present in its waters. But this influence is not manifest, or, at all events, not so manifest in the lower orders, for at great depths the variability of in all latitudes. Now, the higher orders of oceanic the temperature is reduced within very narrow limits creatures inhabit only the surface waters, never sinking down to extreme depths. In the case of some of the lower forms, on the other hand, a very extended pathymetrical range exists, putting out of the question those which constantly dwell on the sea-bed itself, of which I shall presently have to speak. In like manner, light, or rather the absence of it, can hardly be said to determine, in any important forms of animal life. Light is not essential even in degree, the distribution and limitation of the lower the case of some of the higher orders. A large class of creatures, both terrestrial and marine, possess no true organs of vision, although there is good reason for believing that they do possess some special sensory apparatus, susceptible to the influence of light; whilst certain creatures, whose habitation is in subterranean caves or lakes, as in the Magdalena caves near Adelsberg, and the Great Mammoth caves in Kentucky, either possess no organs of vision, or possess them in so rudimentary a state, as to prove clearly that the be compensated for by the higher development of absence or imperfect development of this sense may other senses. It is impossible at present to say to what depth light penetrates in the sea. The photographic art will, no doubt, one day solve the problem. But it is almost certain that a limit is attained, and that, moreover, long before the deep recesses gauged by the sounding machine are reached, where the light-giving portion of the ray cannot penetrate, even in its most attenuated condition; and yet, as shall hereafter be profound and dark abysses, whose colouring is as delicate and varied as if they had passed their existence under the bright influence of a summer ANIMAL LIFE ON THE DEEP-SEA BED, AND shown, creatures have been found down in those OCEAN TELEGRAPHY. (From a Lecture delivered before the Royal Institution, by the United States, and the Dutch Governments, sun! Pressure is the last condition which has to be noticed. Although undoubtedly a highly important one, I hope to be able to prove that it is not of essential value, as has heretofore been laid down, in determining the final limit of animal life in the sea. It is almost needless to state that at the sea level there exists a pressure of 15lbs. on every square inch of surface, due to the weight of the atmospheric column resting upon it; and that the pressure on the successive strata of water in the sea, as the depth increases, is infinitely in excess of this, inasmuch as a column of water only 33 feet in height is capable of counterbalancing the entire atmospheric column, which extends to a height of about 45 miles. Accordingly, for every 33 feet of descent in the sea, putting out of consideration the effect of the superincumbent column in actually diminishing the bulk of the portions beneath by augmenting their density, there is an additional 15lbs. At great depths, therefore, well known, pieces of light wood, let down to a depth the aggregate pressure becomes stupendous. As is of 1,500 or 2,000 fathoms, become so compressed and surcharged with water as to be too heavy to float. But there is a fallacy in this experiment; for the contraction of the woody fibre and cells is a necessary consequence of their submission to an amount of pressure so enormously in excess of that under which developed, from first to last, under the full operation they originated. With organisms which have been of any given amount of pressure, the result would not be of this nature; for the equalization of the although it might possibly exercise some definite pressure, within and without their entire structure, effect in determining their shape, size, or even functions, cannot, I submit, operate in causing the creatures living under it to experience any more detrimental results than we experience from the 15lbs, on every square inch, or about 14 tons on the general surface of our bodies near the sea level. In the mud, or "ooze," as it has been termed, which is brought up from great depths in many parts of the open sea, iminense assemblages of foraminifera are to be met with, chiefly belonging to one species, however. In the absence of examinations conducted immediately on their being brought up to the surface by the sounding machine, it is not surprising that the question as to their occurrence in a living, or only in a dead state, should have remained undecided. Most of the authorities who have written on the subject being of opinion that they do not live at great depths, but that their shells and remains have drifted to the positions in which they were found from shallower waters, or have subsided from the upper strata of the ocean. Professor Huxley was one of the very few who leant to the more correct opinion; he having declared that, although far from regarding it as proved that the globigerina (the species referred to) live at these depths, the balance of probabilities seemed to him to incline in that direction. Other writers have offered surmises on the subject; but these, in the absence of anything like substantial proof, were, of course, only estimated at what they were worth. During the recent survey of the North Atlantic, I found that in certain localities, where the globigerina deposit was of the purest kind and in the greatest plenty, the specimens from the immediate surface stratum of the sea-bed alone retained their normal appearance, both as regards the perfect state of the sarcodic contents of the shell and the presence of the pseudopodia. The latter organs were never seen by ine in an extended condition; but in the specimens alluded to, and in those only, occurred as minute bosses, resembling in shape the rounded rivet-heads on boilers, closely appressed to the external surface of the shell; whereas, in specimens from the substratum, the colour was much duskier, and these bosses were absent. And further, in these pure deposits the shells were to be found in every gradation, from the single chamber, of microscopic minuteness, hyaline transparency, and extreme thinness, to the dense zeolitelike structure of the many-chambered mature shells, which are large enough to be readily distinguished by the naked eye. These facts, when taken in conjunction with the entire absence of the varied remains of other organized structures found in localities where the globigerine are only scantily represented, afford, as I conceive, all but the direct proof, which can only be arrived at on witnessing locomotion, or the protrusion and retraction of the pseudopodia of the organisms in question. enough to suspect that creatures of a far higher type, "In sounding midway, in the direct line between Literature. Treatise on Mills and Millwork. Part I. On the Principles of Mechanism, and on Prime Movers. By W. FAIRBAIRN, Esq., C.E., LL.D., F.R.S., &c. London: Longman, Green, Longman and Roberts. 1861. THIS volume is divided into three sections: first, an introductory chapter on the Early History of Mills; second, the Principles of Mechanism; and third, on Prime Movers. The second section, written by Mr. Thomas Tate, is a separate treatise, which has no immediate or close connection with the remainder of the volume. It is misnamed and misplaced. Instead of treating of the principles of mechanism generally, it deals only with motion and the modes of transmitting it by link work, wrapping connectors, wheel work, and sliding pieces. Instead of being inserted between Mr. Fairbairn's own sections, it might, we think, form a more appropriate introduction to the promised second volume, "On the New System of Transmissive Machinery, and on the Arrangements necessary for Imparting Motion "Now, supposing it possible that these star-fishes were to the various descriptions of Mills." Mr. Tate drifting about in some intermediate stratum of water, has supplied a section chiefly mathematical. Mr. between the bottom and surface, it is evident that they Fairbairn has confined himself mainly to a histowould have attached themselves indiscriminately to any portion of the entire 1,260 fathoms of line; unless, rical, scientific, and practical survey of his portion indeed, they chanced to have been directing their of the subject. We suppose this arrangement has course in a closely compacted column, which was been made with a view to please all classes of traversed by the last extra 50 fathoms of line at the readers. Those who have a taste for formulæ and precise moment of their crossing it. Whether it be possible that they were drifting in such a column, or precise mathematical reasoning will be gratified by floating on a bed of seaweed or other substance, is the perusal of the chapter on the transmission of immaterial, inasmuch as they could only have motion; those who wish information merely, withattached themselves as they did to the portion of line referred to under this one condition. But the very out the trouble of verifying equations, may read act of attachment would, I maintain, be impossible in Mr. Fairbairn's sections on the history of mills and the case of creatures whose movements are so sluggish, on prime movers, and omit the remainder of the when the object which they had to grasp was moving upwards at the rate of two miles per hour (as it volume, without losing the connection. We supdoes when hauled up by the steam-engine), and without pose most readers will skip over the second section, a moment's intermission. But even assuming it to be the work being complete without it; and we possible that they had drifted to the position in which advise those who wish to obtain a connected and they were captured, from distant and less profound depths, the fact of their vitality and vigorously clear view of the subject, so far as the present healthy condition would be scarcely less extraordinary; volume carries it, to pursue this plan. In recom"Most fortunately, as it happened, this collateral evi- for the distance from the nearest point of land, which dence was rendered doubly conclusive by other proofs is a rock off Iceland, is 250 miles; whilst the next mending this course we do not, by any means, unof a most unexpected and interesting kind. I may nearest land, Greenland, is distant no less than 500 dervalue Mr. Tate's portion of the work. For state that the substratum, spoken of as differing in miles. But is must be obvious to every one who is at clearness and accuracy we consider his chapter aspect from the immediate surface-layer, is neverthe- all conversant with the structure of the ophiocoma less identical in composition, the difference in colour and echinoderms generally, that they are essentially superior to those of Mr. Fairbairn. Compare, for arising simply from decay. It contains no living creeping and crawling creatures, and of far too great instance, his statement of the parts of a machine foraminifera; for the minute particles of matter be-specific gravity to float at all under any circum- (page 15) with Mr. Fairbairn's division of the coming gradually condensed and aggregated together by molecular affinity, and the enormous superincummachinery of mills (page 66), and the latter will bent pressure exerting itself only in one direction, read like the repetition of a lesson. The second this is, vertically, its permeability by fluids is thus chapter is evidently the production of a trained completely destroyed, and it is compacted into a dense mathematician; the remainder of the work bears mass of far too unyielding a nature to admit of its being traversed by living creatures of any kind. As the stamp of a man of high scientific attainments the foraminifera die off, their shells and decaying conand great experience in the construction and worktents, together with the minute particles of amorphous ing of machinery. We recommend a separate and matter associated with them, go to build up the calcareous strata of the earth's crust. I would mention careful study of Mr. Tate's portion of the volume, that, in order to determine whether the globigerina especially to those who wish to understand the live as free floating forms in the mid strata of first principles of machinery, and to train themwater, I attached a small open-mouthed bag, at about 200 fathoms from the extreme end of the soundingselves to habits of correct reasoning, logical line, in a locality where the species was most abundant arrangement, and clear statement of truths and in the deposit, and brought it up through nearly facts. -5,000 feet of water without securing a single shell. "But by far the most important and interesting discovery remains to be noticed, namely, the detection of a high order of radiate animal, in a living state, at the depth of a mile and a-half below the surface of the sea. "When we take into consideration the low position of the rhizopod in the scale of being, and the obvious probability, pointed out by Professor Huxley, that a class of creatures proved to extend so far back in time-that is, in a fossil state-must be able to maintain existence under extraordinary and variable conditions as regards light, temperature, and pressure, the sentiment engendered is rather one of wonder, that their vitality at great depths should have been so long and so stoutly maintained, than that it should now be so fully proved. But few persons were bold stances. MR. W. CROOKES has conjectured from his experiments upon the seleniferous deposit from the sulphuric-acid manufactory at Tilkesode, in the Hartz Mountains, that there is a new element belonging to the sulphur group. Its presence was first discovered by the presence of a bright green line in the spectrum of the blue gas-flame. The amount, as yet obtained, is only two grains. Its properties, both in solution and in a dry state, are as follows:-1st. It is completely volatile at a red heat.-2nd. From its hydrochloric solution it is readily precipitated by metallic zinc, in the form of a heavy black powder, insoluble in the acid liquid.-3rd. Ammonia added to its acid solution gives no precipitate in colouration.-4th. Dry chlorine, passed over it at a dull red heat, unites with it.-5th. Sulphuretted hydrogen, passed through its hydrochloric solution, precipitates it incompletely, The introductory chapter is brief, but compreunless only a trace of free acid is present; but in an hensive; the object apparently being to convey an alkaline solution an immediate precipitation of a idea of the important part which machinery has heavy black powder takes place.-6th. Fused with played in the history of human progress. Such carbonate of soda and nitre, it becomes soluble in water. There is little probability that this substance surveys are eminently useful in inspiring millwrights is a compound of two or more known elements. The and mechanical engineers with a love for their prodiscoverer believes that the method of spectrum-fession. Of Mr. Fairbairn's success in executing analysis, adopted to prove that this is a new element, is perfectly conclusive, even when unsupported by chemical evidence. THE amount authorised to be raised for the main drainage of the metropolis is £3,000,000, which has been contracted for at 3 per cent.. of which £600,000 has been received. The sewers intended will extend to 73 miles, 1,743 yards. this portion of his work, we cannot speak highly. His picture is heavy, clouded, and leaves no distinct impression upon the mind. Even a third or fourth-rate man, accustomed to literary labour, but without a tithe of Mr. Fairbairn's talents for scientific and practical investigations, and with no more acquaintance with the subject than is to be | work, which can scarcely be attributed to the The greater part of the volume is devoted to the consideration of the accumulation of water as a source of motive power, its flow and discharge, and the modes of utilizing it by means of different kinds of wheels and engines; second, of steam, saturated and superheated, the varieties of stationary steam engines and boilers; and third, of air, applied in the movement of windmills. No mention is made of the air engine. In discussing the application of water to the driving of machinery, the latest experiments and researches of English and continental engineers have been freely used. Mr. Fairbairn's own lengthened experience in the construction of reservoirs, and the erection of water wheels and machinery for water mills, has enabled him to render this portion of the volume a standard work of reference upon this subject. Engineers and millwrights will naturally expect to derive great assistance from the labours of one who has been so long and so successfully engaged in this department of engineering; nor will their expectations be disappointed. We need scarcely point to the sections on the formation of reservoirs and the construction of water wheels, carried on under the author's own direction, as specially interesting and valuable. In treating of the flow of water in open channels, Mr. Fairbairn has overlooked the late investigations on the velocities of currents, by Mr. T. Archer In discussing the properties of steam, Mr. Fairbairn has availed himself largely of his own researches, already given to the public through his papers, read before the British Association and the Royal Society. We need not now refer particularly to this portion of the work, farther than to state printer or the mere oversight of the proof-reader. In the engraving and placing of the plates As any work on mills and their machinery bear- labours of one who has long ranked among the outline of Mr. Fairbairn's work. We wish to show that it deserves the study of men engaged The chief recommendations of this work to students are its brevity and perspicuity. It embodies, in a few pages, a large number of the most important facts connected with the construction and working of steam engines. Perpetuum Mobile; or, Search for Self-motive Of all the subjects that have at one time or another The sixteenth century affords little to remark upon; if then attempted, the schemes of such inventors at that carly period are unknown. In 1594, Edmund Jentill professed to have discovered a perpetual motion of sufficient force to dryve a myll." But how, or by what means, we are not informed. In the seventeenth century, plans by streams, pumps, and magnetism were not uncommon, as we find in the writings of Fludd, Bettino, Taisnierus, Wilkins, and others Such inventions for that, the next, and the present centuries have been classified and enumerated by Mr. Dircks as follows: First, by atmospheric changes, upon which we need not dwell. Second, chemical action, as given by Dreble, Boyle, and others; all very doubtful. Third, galvanic, as ingeniously shown in De Luc's column, Zamboni's and other experiments. Fourth, by hydraulics; as in the applications of the Archimedean screw, the syphon, and various water engines, combining these with pumps, endless bands of buckets, &c. In the 7th vol. of the MECHANICS' MAGAZINE, 1827, is a full account of Sir W. Congreve's attempts to apply the To this class, that Mr. Fairbairn is still prosecuting his experi- the practical, and therefore most important, truths principle of capillary attraction. of science. Amongst the foremost of these stands also, belong the extraordinary patents of Dr. W. W. Sleigh, for his hydro-mechanic apparatus, counteracting re-acting engine, hydrostatic engine, and his singularly-named "neutralific motive ments, to determine precisely the law of expansion of superheated steam. The importance of the subject, and the great attention which the writer has devoted to it, is an ample apology for the amount of space devoted in this work to the "pro- work more highly than to say that the greater power engine," patented in 1860. portion of it will be found intelligible, interesting, similar are the patents of W. Eatoton, 1846, and Compte de Predaral's, 1833, for the carrying out of which a public company was attempted to be formed. perties of water when converted by the agency heat into vapour or steam." of and useful to all classes. Lessons and Practical Notes on Steam, the Steam In treating of steam engines, Mr. Fairbairn illustrates the progress of improvement in this class of machinery by examples of the best and most recent construction, and gives engravings of those at Saltaire, of 100 nominal horse-power each; also of the horizontal, high-pressure, non-condensing engines, called thrutchers; the marine engines erected by himself for driving a cotton-mill in Staleybridge; and Woolf's, which is used extensively on THE object of this work is to direct the student of the Continent. The remaining chapters on this engineering into habits of thinking and reasoning department of the subject are mainly a clear, con- for himself, and for this purpose it may prove cise summary of the more important facts regard- useful. The author lays no claim to either a ing high-pressure engines; the history, construc- scientific or practical discussion of steam, the tion, and use of boilers, with a brief notice of their steam-engine and its appliances, the paddle wheel, accessories ; the feed pump, feed-water heating the screw, surface condensers, the strength of apparatus, water gauges, steam gauges, safety materials, or other miscellaneous subjects connected valves, &c.; concluding with a history of the most with these which are discussed in this volume. prominent plans for the prevention of smoke. In We may recommend to the notice of young his allusions to Mr. C. Wye Williams's system, he engineers in this country his chapter on the variety styles its author "pertinacious." We suppose he of expansion valves and arrangements for cutting means persevering, and we are led to make this in-off steam, which are commonly used in America. ference from the fact that there are several gram- Also the chapter on casualties, containing directions matical errors (see page 11) in Mr. Fairbairn's regarding the mode of providing against them. Somewhat Fifth, magnetic; of which several are on record, but not accepted. Sixth, pneumatic, hydro-pneumatic, &c. Several ingenious arrangements appear under this head. But the most prolific class is the Seventh and last, wheels and machines. Of these the most interesting and distinguished are the wheel of the Marquis of Worcester, tried in the Tower some time previous to 1649; and that of Orffyreus, exhibited in Germany about 1717. It is remarked as "a singular coincidence, that the only two accredited inventions, acting as evidences of perpetual motion, should both have been treasured by their inventors, and yet be lost to posterity." Mr. Dircks clearly neither approves nor condemns the study. He shows that it is wholly unsupported by existing scientific views, and quite opposed to all known mathematical principles. The only difficulty in the way of giving a decisive opinion arises from the fairly-assumed trustworthy character of all the evidence he has been able to |