THE MECHANICS' MAGAZINE,

PATENTS ON WHICH THE SEVENTH YEAR'S
STAMP DUTY HAS BEEN PAID.
103. C. Lungley.
123. R. Whytock.
142. H. B. Barlow.
156. J. Brown.

172. J. Jobson.
181. J. Needham.
187. A. Miller:
214. T. Kennedy.
237. H. Jäger.

246. G. H. Cottam.
251. A. E. L. Bellford.
272. J. Hill.

275. A. R. de Normandy.

THE

MECHANICS' MAGAZINE.

LONDON, FRIDAY, OCTOBER 14, 1859.

SCIENCE AND THE PRINCE CONSORT. THERE are two features very strongly imprinted on the age in which we live. For one thing our time is marked by a very high development of humanity. We were greatly impressed by this in a recent visit to one of our public lunatic asylums. We entered a spacious, airy, handsome edifice, in the depth of a rural region, looking out on wood, meadow, and river. The physician in charge of the whole institution, a keen, cultivated, humane gentleman, and of an activity bright and incessant as a bird's, led us through all the wards, where we saw some six hundred insane persons. Numbers of them were peacefully employed, at washing, or cooking, or baking. None of them had any restraint on them beyond the eye of the attendant, and the walls of the building. All was cleanly and handsome that met their eye; their bed and board were of the wholesomest and

best. The very lady of the house, the physician's wife, was just as devoted to these poor insane persons as he himself, constantly amongst them, and expressing intimate affection for several of them; entertaining them with music on the Sunday, and in winter evenings getting up concerts and dramatic exhibitions for them. Altogether, the scene was a living symbol to us of our time, and made us feel afresh that the world has never before seen so high a development of humanity as that which meets the eyes of the present generation.

growth in England, partly because we English
are so wedded to what is immediately useful,
what immediately shows a return in pounds,
shillings, and pence; and partly from our ex-
cessive devotion to antiquity, that "till of late
"has almost systematically excluded from our
"school and university education" the great
subjects and the results of modern inquiry,
while it has given to antique things that liveli-
ness of interest we feel all through life in the
subjects we studied in early years.

The illustrious speaker lays great stress on
the absence of all professionalism and officialism
from science. Knowledge in his eyes has no
aristocracy or priesthood. Its genuine students
are not "a secret confraternity of men jealously
"guarding the mysteries of their profession";
their activity is "the republican activity of the
"Roman Forum." But if boldness and freedom,
the Prince reminds us, are the characteristics
of the philosopher, equally so is reverence. The
more he explores the more he becomes aware of
"the boundlessness of the universe, whose con-
"fines appear ever to retreat before our finite
"minds." True thinkers are "not conceited
pedants, wrapped up in their own mysterious
importance, but humble inquirers after truth;
«pilgrims towards a Holy Land-God's Truth
"not God-defying Titans, but reverent, pious
-God's laws, as manifested in His works, in

66

"His creation."

Servility to mere rank as such we have supreme contempt for; but we confess to an unusual joy when a man in a high place has a higher light in him than those in low and even in high place around him; and such we conceive to be in this Prince's mind.

THE GREAT EASTERN.

But notwithstanding the altered condition of things to which we have before alluded, it must not be understood that the state of the ship was unsusceptible of further improvement. On the contrary, we think the services of some of the sub-contractors-all of whom were notably ready to lend their aid at any sacrifice to themselves-might have been somewhat further continued with advantage. Had Mr. Hall had an opportunity of finally adjusting his sails to his own satisfaction their set would doubtless have been improved; and Mr. Westhorp's great experience in equipping vessels might have been further applied to equally good purpose; but, as we have on former occasions urged Captain Harrison to take the ship in his own hands, and as Mr. Scott Russell had strenuously pressed the Company to keep their engagements with the public by proceeding on the trial trip on the 8th inst., it would probably be unfair to charge the Captain with any remissness on these points. For this cause we also refrain from noticing some other matters which, to a certain extent, challenged criticism when we entered the ship on Saturday.

One of the most important and satisfactory consequences of the late explosion was visible the funnels; these have been altogether done in the absence of all water-heating cases around away with, the air now flowing freely through

the

pro

space contained between the funnels and the casings. Thus, all accidents like the late one are rendered impossible in the ship for the future, although security has, of course, been gained at the expense of a certain amount of economy. The slight injury which the boiler sustained has also been repaired. This is so small a matter that it would not need another word but for the exaggerated importance which The other characteristic of our time to which some writers for the newspapers have attached we refer is its boldness, comprehensiveness, and THE trial trip of the Great Eastern has at last to it. These gentlemen tell us that the concertainty of mental inquiry, which expresses been made without accident, misadventure, or tractor is at issue with the Board of Trade itself in its favourite term-science. We had a failure of any kind. By the untiring activity Surveyor and the Directors of the Company on notable example of this in the speech of the and exertion of the contractor, the injuries this point, the latter contending that the inPrince Consort at Aberdeen, which we re- caused by the late explosion were so far re-jured plate should be replaced by a new one, printed in our journal a fortnight ago. It was paired as to admit of the trip being entered and the former that the repair has been a fine specimen of the best mind amongst us. upon on Saturday last. On reaching the ship perly made already by riveting a piece of plate What choice, pure English the language was, on the morning of that day we were happy to over the injured part. We think the conand of such delicate precision and beauty. observe that her condition was much improved tractor is quite right. The word "patch" is What graceful personal modesty the speaker in many ways. Sails were bent upon the yards all that alarms those who think otherwise-as showed. How full the discourse was of the and gaffs; the steering wheel was furnished if a riveted boiler itself is not a mere agglo old German solidity and seriousness of purpose, with chains rove, so as to increase the control of meration of patches! No sensible man would that marks all the German people, whether in the steersmen; the water-tight bulkheads were as think of unriveting a plate from a boiler, and the old Fatherland or in Angleland. The term sound and complete as was necessary; the staffs causing all that weakness and liability to leak science in this address is made to embrace the of the two engine-rooms and boiler departments which may result from doing so, simply to rewhole range of the human mind. There are were made up and well organized; the captain pair a slight crack which does not even extend three objects of man's contemplation and in- had a crew in whom he appeared to possess wholly through the metal, and which can be as quiry-Nature, Man, God. The human mind confidence; and altogether the ship presented effectually repaired by riveting a piece of plate has two methods of working-analysis and a far more satisfactory aspect than on the occaover it. As to the remainder of the repairs synthesis. It dissects into parts, observes, sion of the trip from the Thames to Portland. which the explosion rendered necessary, it is examines, reasons about each part; or intui- And this is a proper place for remarking that sufficient to say they are fast approaching comtively it grasps the law that binds and controls the materials and workmanship which have pletion. the parts and knits them into a whole. All been supplied by Mr. Scott Russell throughout follow this method, says the Prince-the child, the equipment of the ship are of the very best the man of mere practical instinct, or the phi-kind-a circumstance which is not always oblosopher. The child, as soon as his first surprise and ecstasy at the new universe subside a little, begins to ask the how and why of things. He practises his analysis by pulling his toy to pieces to discover how it works; or he performs a splendid generalisation; as, for example, when the fire burns him he affirms to himself that fire burns in every instance, at all places and times, though he has only experienced one instance of its burning power. The practical man is instinctively impelled to philosophise, in his rough, home-spun method, on the facts he is brought into contact with. But the philosopher, by stronger instinct and by conscious s-li-determination, directs his eye to every part of the great All.

Science, the Prince hints, has been of slow

We come now to the trial trip; and at the outset would warn our readers against expecting too much, in the shape of data, from it, as servable in contract work. The firms to whom regards either the speed of the ship or the he committed the masting, rigging, and sail- economy of her boilers and engines. An ordifitting, for example, under sub-contracts, are nary ship must be subjected to many trials among the most eminent in England-the under various circumstances before final conMessrs. Ferguson and Co., Messrs. Westhorp clusions on these subjects can be arrived at; and Co., Messrs. J. T. Hall and Co., and Messrs. and in the case of the Great Eastern, which is J. and É. Wright-and we are enabled to state, an extraordinary ship in many respects, it will on the authority of most of the heads of these doubtless take a considerable time-perhaps a firms, that Mr. Russell has rigidly enforced but voyage or two across the seas-before her capaone condition upon them, viz., that everything bilities are properly understood. A deeper supplied should be of the very best kind manu- immersion, a different trim, an improvement in factured by them. The masts and spars, stand- the form of the screw, an increase or decrease ing rigging, running gear, and sails of the ship in the reefing of the paddle floats, greater exall attest the faithfulness of the sub-contractors perience on the part of the firemen and stokers to this condition, and reflect the highest credit-all these and some other things may tend to upon Mr. Russell, the general contractor for the whole.

modify her speed hereafter. But whether a greater speed is ever to be attained or not, the

late trial trip was very satisfactory. For a short time on Sunday morning the speed predicted from the first by her builder-fifteen knots an hour-was attained. The fore and aft sails were set at the time, it is true; but the moderate breeze which was blowing could have added nothing to the speed derived from her engines, the only advantage of the sails being that of steadying the ship as she crossed the swell that beset her in her passage from the Scilly Islands to the Old Head of Kinsale in Ireland. When this speed was reached the screw engines made from 40 to 41, and the paddle from 11 to 12 revolutions per minute, the steam [boiler] pressure being about 22 lbs. We have no doubt whatever that if tried at the measured mile under moderately favourable circumstances it will be found that her speed will fall nothing short of the fifteen knots which she has already made.

240, and the Miranda no less than 247 by the screw engines, and made it necessary to stop second formula; but the very best of these them for a very few minutes. But for these fall, as will be seen, considerably short of the occurrences, which were so insignificant as to Great Eastern's numbers in both cases. deserve mentioning only for the sake of strict Still, as we said before, we believe the Great accuracy, it might have been said that both Eastern will yet prove herself capable of more engines ran the whole forty-eight hours, from than she has hitherto accomplished. And we Portland to Kinsale, and thence to Holyhead, find reason for believing this in the results of a without ever stopping or manifesting the slightfew experiments which were made off Holyhead est tendency to derangement. This is a result on Monday before we entered the harbour. The upon which Messrs. Blake and Langdon ship was there tried first under paddles alone and (Boulton and Watt) and Mr. Scott Russell dethen under the screw alone, and although the serve the warmest congratulations. The paddle one propeller had in each case to drag or force engines having, of course, a speed much inferior the other through the water, speeds of no less to that of the screw engines, doubtless offered a than 8 and nearly 9 knots respectively were better chance of success to their constructor attained. We watched these experiments very than the others, but they are nevertheless a closely, carefully noting the periods at which marvel of mechanical construction. The four the engines were stopped and the log cast, and ponderous cylinders, each weighing with its whatever statements may have appeared else-piston and piston rod no less than thirty-eight where we assert, on our own carefully-acquired tons, and moving with a stroke of fourteen feet, There can be no question that this result is knowledge, that after the screw had stopped en- worked with a perfection which elicited conmost satisfactory, and when the dimensions tirely for several minutes the paddles (driven tinual admiration from the most experienced and horse-power of the ship are considered will by 1,000-horse power engines) propelled the practical men on board the ship. be seen to surpass everything hitherto attained. huge vessel and dragged her screw at no less As to the sailing qualities of the Great Eastern, The famous Persia, which is of but little more than 8 knots, measured with the log by the the trial trip showed absolutely nothing. than one-sixth of the registered tonnage of the ship's officers; and that when the paddles had Every scientific man must know perfectly well Great Eastern, and yet has more than one-third nearly (but not altogether) come to rest the that when a ship is steaming at the rate of of her nominal power,* has made no more than screw (driven by 1,600-horse power engines) from fourteen to fifteen knots per hour with a fifteen knots, we believe, while in the tabulated propelled her at 9 knots. Now, if the screw moderate breeze considerably before the beam, lists of the Royal Navy+ we find no vessel of had been properly immersed, it would have no increase of speed can possibly result from anything like the same efficiency. The Ad- produced a considerably higher speed than the hoisting fore and aft sails. By sheeting the miralty there give us two formula by which paddles, or should have done so, seeing that its sails well home, as was done on Sunday, you they test the relative merits of steam-ships; engines were more powerful than the others by may, of course, find them of great service in the former involving the speed, midship section, 60 per cent. ; and there can be little doubt that steadying the ship, as we did; but even this and indicated power; the latter involving the when the ship is brought to a deeper draught effect is, to a great extent, due to the vessel's weight instead of the midship_section. To of water aft, the screw will contrast less unfaown motion through the air, which motion canapply these tests to the Great Eastern we re-vourably with the paddles. It is only due, not, of course, be available as a source of speed. quire of course to have her indicated power, however, to Mr. Scott Russell to say that he At the same time, there can be but little doubt midship section, and weight, and these we are took no part in bringing on the trials which that when put under an amount of sail proporable to supply with a sufficiently near approxi- terminated so favourably for his paddle-wheel tionate to her size, the great ship will be second mation to the truth for our present purpose. engines; on the contrary, he objected to making to none as a sailing craft. Her behaviour, so far Before leaving the ship we ascertained that them at all during the late trip, because time as it has been observed, has given great satisthe total indicated power, developed when the could not be afforded for disconnecting the faction. As to her steering, it may be said that engines did their best, was about 7,200-horse paddles and the screw from their engines so as in running at full speed up the Irish Channel power. We have further found by approximate to give a fair opportunity for each propelling on Monday morning, her helm was put over calculations that with the draught of water apparatus to display its full power; and in seventeen degrees, and the ship turned through with which the ship left Portland (25 feet aft, doing so he incurred the displeasure of some of the complete circle in eighteen minutes. 21 feet forward, mean 23 feet) her midship sec- the passengers-newspaper reporters and others Through a deficiency of power in the steering tion must have been about 1,600 square feet. who of course understand such matters in-apparatus, or rather in consequence of that Further, her weight must have been at least finitely better than men like Messrs. Blake, apparatus not yet affording convenience for the between 17,000 and 18,000 tons-say 17,500. Langdon, Scott Russell, and others. We are application of sufficient power to it, the helm We know that this must be near the weight, sorry to have to add that even Captain Harrison cannot at present be got hard over at full speed. and at any rate cannot be in excess of it, be- might with advantage have shown less disposi- The employment of a third steering wheel cause the mere iron in the hull weighs 8,000 tion to interfere with such matters as the reefing with the barrel prolonged to receive it will tons, the engines and boilers about 2,000 tons of the paddle floats and other engineering obviate this difficulty; and when this has been (reckoning the weight three-fourths of a ton per points, in reference to which he evinces no un- done, and the helm is capable of being put nominal horse-power), and there were 6,000 tons usual skill or knowledge. It is satisfactory, hard over at full speed, she will, of course, turn of coals on board, in all 16,000 tons. To this however, to know-and we state it from an in- in much less time. we add 1,500 tons only for the weight of wood-timate acquaintance with all the facts of the work, masts, spars, and rigging, paddle wheels case that Mr. Blake (the representative of the and screw, water in boilers, and everything Boulton and Watt firm) and Mr. Russell, have else on board, which certainly cannot weigh maintained the most complete cordiality posless than that amount. Taking, then, these sible throughout the harassing transactions of quantities the speed 15 knots, the midship the last few months. The engineers themselves section 1,600 square feet, the displacement being agreed on all points, it does not much 17,500 tons and substituting them in the two matter whether people who know nothing of Admiralty formulæ successively, we get for the engineering think them right or wrong. Great Eastern's characteristic numbers 750 and

316 respectively. Now, none of the Admiralty vessels reach such numbers as these. We have the Agamemnon giving 664, the Miranda 780, the Tribune 686, the Algiers 687, the Simoom 688, the Desperate 697, the St. Jean D'Acre 701, the Princess Royal nearly 725, and the Cruiser nearly 728, by the first formula; and we have the St. Jean D'Acre giving 201, the Tribune 202, the Princess Royal 203, the Cruiser 220, the Desperate 224, the Simoom The Persia's tonnage (registered) is 3,300; her horsepower 900. The Great Eastern's tonnage is 18,915; her

total horse-power 2,600.

Published in the Supplement of the MECHANICS' MAGAZINE for February 18, 1859.

obtain unquestionable and detailed data reWe were not able before leaving the ship to specting the consumption of fuel, &c., which we the less regret for reasons before stated. We may say, however, that the consumption of coal tons per day in the paddle-engine boilers, and was said to have averaged from ninety to 100 proportionately (to horse-power) in the screwengine boilers, the average steam pressure being about eighteen pounds. The coal burnt was Hickson's Merthyr. On Monday morning the superheating steam apparatus was put into action in one of the boilers, and was found to raise the temperature of the steam from 2-46 degrees to 286.

It is very gratifying to know that both the engines of the great ship work most admirably. Owing to a little looseness of the connecting rods upon the crank pin, the screw engines at present make more noise than is desirable, and less derange themselves prematurely; but a if the defect were not remedied, would doubtvery little expense and trouble will suffice to trip of this wonderful ship has put us in possesSuch are the principal facts which the trial make all as it should be in this respect. On sion of. Hereafter, we may be able to afford Saturday evening, the escape valve of one of the more detailed information. But, however that paddle cylinders was held partially open for a may be, we have only to consider carefully what few minutes by mud or sediment of some kind, has been already stated, and to supplement but this was speedily removed without stopping that by our knowledge of the general advantages the engines; and, on Monday afternoon, a simi- which the great ship was designed to secure, lar thing occurred in one of the cylinders of the ❘ and doubtless will secure, in order to see that

in the Great Eastern her proprietors possess the most promising vessel in the world.

On another page will be found a detailed statement of the working of the paddle engines, with which we have been favoured the last thing before going to press.

STEAM-SHIP ECONOMY.

Now, to all this we can cordially express our assent, and acknowledge that Mr. Atherton is doing good service by bringing home to the understanding of every one, and enabling him, as it were, to place his fingers upon what any purchaser of steam-power applied to marine locomotion may fairly and reasonably expect to obtain for his money, "being based on data

"within the limits of actually realised results." There are doubtless certain anomalies presented by most steam-ships to which these formula have been applied to which we shall not now advert; but making due allowance for all these, towards mercantile transport economy-the we cannot but think that much will be gained efficient performance of any specified service at the minimum of cost and of wear and tear-by the diffusion of such knowledge as Mr. Atherton in this paper brings prominently forward.

it. The Chairman of the Committee, Admiral | horse-power, and fuel in any vessel, for the Moorsom, has long been connected officially service required to be performed of her. with the Chester and Holyhead Railway Company, whose boats perform the passenger service between Holyhead and Kingston; and he seems to have taken great pains to arrive at the best mode of ascertaining the performance of these vessels, and of securing due economy in In another portion of our impression for this their management. The most important and week will be found a paper read by Mr. Charles Valuable returns are, as might naturally be exAtherton, Chief Engineer at Her Majesty's pected, from this source, and are a tolerable inDockyard, Woolwich, at the last meeting of the dication of the nature of the information which British Association, on "Mercantile Steam the Committee have thought valuable. Economy "Transport Economy as affected by the Con- and efficiency being the great objects aimed at "sumption of Fuel." At the same meeting was in the management of these vessels, it may not presented a Report by the Committee appointed details of these returns at some length. They be uninteresting to lay before our readers the at the Leeds meeting, "On the best mode of consist of, 1, a return of the performances of "recording facts of performances of vessels at the Chester and Holyhead Company's steaminteresting paper by Admiral Paris, of the Im-vessels, under a trial for a standard test. perial French Navy, constituted the cream of 2. Return of the speed and consumption of fuel the proceedings of section G at Aberdeen. of the steamboats under regulated conditions of The insufficiency, or rather gross inaccuracy And there cannot be a doubt that they all time, pressure, and expansion, for prior periods have reference to questions of the most in- (1848 to 1850). 3. Return of the speed and and worthlessness of the present mode of estimating nominal horse-power, and the importteresting and important character that can be consumption of coal of the express and cargo ance of some efficient mode of valuing the actual made the subject of discussion in a mercantile boats, under regulated conditions of time, pres-performance of a steam-ship, have not been concountry. Our readers will remember that this sure, and expansion, from January 31st, 1857, fined to this side of the Channel. Admiral to December 31st, 1858. 4. Verification of is by no means the first time we have stepped consumption of coal from January 1st, 1857, to Paris, who has been mentioned several times in forth into the arena to address ourselves to December 31st, 1858, to the introduction of a the course of our present notice, is the author these and kindred subjects. It most unfortu- similar system into their own management. of a pamphlet entitled, "Utilisation Econonately happened that our business formerly was "mique des Navires a Vapeur," published in to disembarrass the real questions at issue from It is clear from what we have said that this the course of last year at Paris. We can do the deadly embrace of crude and unsound Committee of the British Association has been little more than offer a mere outline of his reconfine its operations to the business directly the demolition of the present mode of valuing doing good service, having been content to marks. The first half of his paper is devoted to entrusted to it, and resisting the temptations nominal horse-power, and proposing another in

"sea under all circumstances." These and an

theories of political economy in which they were tightly held. Mr. Atherton had, in fact, contrived to bring these questions before the British public in such a manner as to render to soar into more inviting but forbidden regions. its place. From him we learn that there are

their free and temperate discussion almost a matter of impossibility. Now, happily, the selfishness of the shipping interests, and frantic

invocations of the Government and Parliament to take the shipowners' concerns under their paternal care, are no longer the order of the day; and the whole question of steam-ship performance is brought down to the sober, but perhaps less exciting region of calm philosophic inquiry, from which they had unfortunately soared on the back of Mr. Atherton's winged imagination. We congratulate that gentleman on the change that has passed over the spirit of his dream; and as our objections to his lucubra tions have never been of a personal nature, but prompted by our anxiety that the interests of science should not be sacrificed by a false alliance, we willingly hail him as a friend while he consents to tread with us within the charmed circle of truthful and passionless inquiry.

To do the Committee of the British Association justice, they seem from the commencement to have recognised and adhered to the proper sphere of their action. Their first object, and a most important one truly, was to obtain experimental data of such a nature as should appear likely to promote improvement in the construction and performances of steam-vessels. Their action has been chiefly taken with a view to carry out this laudable design. They have applied to various quarters-the Admiralty among others for information, suggesting a new form of return for trial performances, which they considered more complete than that now in use. Finding, by an examination of logs communicated to them, that the particulars given in them were very incomplete, they have drawn up another form of log which they propose for sea service, in which it seems they received very material service from Admiral Paris, whose valuable services as a corresponding member they early obtained. All this is so rational that, were it not for the somewhat different course adopted by a former committee, we should think it unnecessary to make special notice of

The contribution of Mr. Atherton is directed

to ringing all the changes that can be got
out of the combinations of the two formula

C =

V3 D3 ind. h. p.

and C- =

w

seven different methods of calculating the nominal horse-power in the French navy-the main principle, however, being the same in all. From the number of cylinders, the diameter and length of strokes and number of strokes of in which C and C are constants, V is the speed the piston of each cylinder, it is easy to calcuof the vessels in knots per hour, D is the dis-late the volume of steam used per minute or placement, and w is the weight of coal consumed per hour in cwts. We may state in a very few words the main objects which Mr. Atherton seeks in this paper. Assuming the consumption of coal to be 24 lbs. per indicated horse-power per hour-which has been attained in a good model, but is considerably below what is usually attained in practice-assuming also the constant C from the formula

C

=

V3 D} ind. h.p.

per second (the French, it appears, very frequently take the second for the unit of time, while we always employ the minute); to obtain the power there now only remains the element of steam pressure on the piston, which is always assumed both here and in France to be that given by Watt for the purpose of obtaining the of strokes assumed in this calculation is also nominal horse-power. Moreover, the number borrowed from the actual use of the early engines, and all marine engines work up to a power varying from three to four times that correto be 250, also deduced from a high type, he sponding to the number obtained by such a procalculates the consumption of coal at 10 knots cess. The most important element of power is enper hour for vessels of various sizes and horse-tirely omitted in this calculation, viz., the boiler power from 250 tons displacement and 150 indicated, or 52 nominal horse-power, to 25,000 tons and 3,420 indicated, or 1,129 nominal horsepower. As in the performance of a voyage of definite length the consumption of coals varies as the square of the velocity, it is easy to reduce the consumption for any speed actually attained to that which it would be for 10 knots. The table constructed on this principle enables the persons interested to estimate the greater or less efficiency of any particular vessel by comparing the actual consumption of coals with what it ought to be according to this table the efficiency, of course, being the greater for the less consumption, and vice versâ.

Again, he constructs another table, assuming the same data for consumption of coals and index of dynamic performance, for vessels of various displacements, ranging from 1,000 to 25,000, and for the various speeds of 10, 15, 20, and 25 knots; the object now being to guide a constructor, presuming him to choose a type not inferior to the best, in adapting the size,

with its heating surface and capability for production of steam. There can be no difficulty, then, in showing that all calculations based on this principle are delusive. The only question then is, what measure is to be substituted for this defective measure. In our country, by tacit consent, horse-power, as shown by the indicator

-calculated, that is, from indicator diagramshas practically superseded the nominal power. All theoretical tests of efficiency are referred to the indicated horse-power, it being assumed that in all well-constructed engines the loss of power through friction of the several parts of the engine, &c., falls within a certain per-centage varying within narrow limits, and that the work delivered at the working parts may be taken as bearing a fixed ratio to the whole work as shown by the indicator. To this, however, Admiral Paris demurs; he thinks the indicator too small and uncertain an instrument to place entire dependence on for so important a purpose. A little disorder in the spring would involve a considerable error in the calculated power; and

From the earliest records extant in the kingdom bearing upon the subject, we gain some curious information touching the methods of coining pursued in the infancy of our existence as a civilised The "hammer and die" method of coining exnation; but there is an amount of vagueness about isted for a considerable time, and the coins resultthese documents which was evidently intended by ing from it exhibit a sharpness of finish which the writers to hedge in the subject by difficulty neither the coiners of the Heptarchy a thousand and doubt. It is plain, however, from their moth-years since nor those of Whitechapel or Birmingeaten and musty testimony-rendered from their British Museum-that in the early Saxon and niches in the State Paper Office, and in the Norman times there were a variety of small Mints established in various parts of the country, and in some cases two or three in the same city or town. These petty places for the manufacture of current coin were either under the direct supervision of the king, of some favourite prelate, or of a subject whom his majesty delighted to honour. Each of

ham of to-day are able to produce on cast pieces there are, as we are informed, preserved several of of money. In the museum of the Tower-hill Mint the blacksmith-like tools or dies which were used in the process last referred to, and even collars of lead with which the workmen held them whilst being struck, in order to prevent the jarring caused by the blow from being transmitted to their own muscular systems. This mode of coining, however, was attended with several draw