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p. 27.

tinurus ; but it is the continuous effort of one stroke is finished, the area above the piston man, and against the tempest and the surge will be diminished one-half, and the density the boat stirs not a foot from the shore. of the compressed air will consequently be But change the plan of operation; adopt double, or 200 lbs. per inch, which, on the the aggregate and concentrated plan, instead return of the upright lever L will powerof the separate and continuous. Let the fully assist the steam-engine or principal ten men pull all at once, and the boat bounds

moving power in effecting the forward or over the wave and makes head against the main stroke of the propeller. If found destorm; a pause for a moment ensues after sirable a small portion of air may be ad. the first stroke, and the tempest seems likely mitted underneath the pneumatic piston, to drive back the boat ; but after a brief in which, being compressed on its descent, will terval, another pull —a long pull, a strong act as an air cushion, to prevent any shock pull, and a pull altogether,' (the principle at the end of the stroke. The diameter of has become a proverb,) the boat again springs the pneumatic cylinder as well as the degree forward with quickened speed; its own mo. of compression on the air, must be left to mentam now keeps it moving during the in the judgment of the constructing engineers. tervals of the strokes, and by the united and In the drawing (figure 1) the cam of the repeated efforts of the ten rowers judiciously wheel No. 1 is represented in the position of applied, finally reaches its destination.

having just completed its action on the lever “ No single and separate efforts of the L, and propeller P in the principal moveten men, however rapidly applied, in succes ment propelling the vessel forward ; and the sion, one after the other, could have accom cam of wheel No. 2, just about to commence plished the object. And in what does the the slow backward movement by which the continuous splashing of the ten floats of the reserved power is raised, and the levers or paddle wheel during every stroke of the en propellers quietly brought back and placed gine-in what does this differ from the dis in position for the next effective stroke."jointed and separate efforts of the ten men in the life boat? The ordinary paddle wheel Mr. Booth calculates that the gain distributes the power of the engine equally over the whole circumference of the paddle

which may be effected by this double wheel, say 100 feet. I propose to concen

concentration of power is actually as ten

to one! trate the whole power of the engine into a strong pull of ten or twelve feet, wherein “ We will suppose that it is desired to the reserve power is accumulating for the

make the forward stroke of the propeller equal next stroke."-p. 33.

to the pull of a thousand horse. If the conMr. Booth proceeds, in the second

centration be ten-fold, a steam-engine of a

hundred horse power should suffice ; or, to place, to explain how he would accumu. late or store up the power not made use

cover extra friction, &c., say, 200 horse may

be required. The pneumatic cylinder and of during the nine-tenths of the stroke

cam wheels will effect the rest. A cylinder when his propeller is inactive, and give 3 feet diameter with a stroke of 2-6 and it out when wanted in aid of the efficient charged with air at 100lbs. per inch prestenth. The following is the plan which

sure,

and slowly compressed into about onehe proposes for this purpose :

half its bulk, would answer the purpose.”" Q, Fig. 1, is a pneumatic cylinder, closed at each end. The stroke of the piston will be Mr. Booth anticipates that people may to the same extent as the motion of the up wonder how he is to get a valve plate or per end of the upright lever L to which the

paddle-board large enough to act as a piston is attached by a chain and wheel, as

fulcrum to his thousand horse pull or shown in figure 1, or other efficient mode of connexion. The reserve power is brought

lever ; but he gives the following reasons into action as follows :-The cylinder Q is

for believing that one of corresponding to be filled with air more or less compressed

dimensions will not be at all required ; by a small force pump. If the stroke of the that, in fact, “ a very small” one will anpneumatic piston is 2 feet 6 inches, the length swer every purpose. of the cylinder space should be 5 feet. When “I will admit that in the proposed scheme the piston is at the bottom, the air must be it will be desirable to have valve plates large forced into the cylinder, to the density, I enough to meet a far greater resistance in will suppose, of 100 lbs. per square inch (the the water during the main stroke of the proexact amount of compression to be at the peller, than the resistance at present offered option of the engineer). As the cam wheel, to the paddle wheel during the same extent No. 2, moves the propellers slowly back of motion. But a small valve plate or padwith the valve plates open, the pneumatic dle board will accomplish this object. I shall piston will be slowly raised, and when the

suppose that on the proposed plan the pad.

p. 40.

dle board will be three times as deep in the Booth's various positions, but we shall water as the floats of the ordinary paddle add a few general observations, which wheel. By the law of hydrostatics, this con may serve to indicate the grounds on dition would give five times the power to the which we rest our opinion. water as a fulcrum of resistance, which is

The concentration of effort which Mr. its proper function in relation to the paddle Booth proposes to accomplish by his reboard. Consequently a paddle board of three

ciprocating-valve propeller, though treatsquare feet area would be as efficient at the increased depth as one 15 feet area at the

ed by him as something quite new, is no

more than has been tried to be accomlesser depth; but that is not all. The vi. brating propeller may, in its principal move plished many times before ; it is the obment, be made to move twice as fast as the ject of all the feathering paddle-wheels paddle wheel, wbich will increase the efficiency

which have ever been invented; and the again of the fulcrum probably two-fold ad object also of every sort of wheel in which ditional, making the 15 feet equal to 30. I it is endeavoured to place the floats so that think there need be little apprehension, they shall only act against the water when therefore, respecting a very small valve plate they can act with advantage. A paddlebeing sufficient to give out the requisite wheel, the floats of which act only during power, the comparison being between deep the front half of each revolution, is just as water and high velocity in the valve plates, good an example of intermitted action, as and shallow water and a slower motion in the the case of the boat with its ten rowers, ordinary paddle boards."-p. 41.

so much dwelt upon by Mr. Booth. The Assuming that Mr. Booth is right in paddles, it is true, act one after the other, his new theory of concentration, and the wbile the rowers act all together, but the new practice which he seeks to found difference in time between the two operaupon it, this grand practical result would tions is so extremely small, as, in all profollow, that the whole marine steam bability, to reduce them, in point of effici. power of the country might be at once ency, to a very near equality. Between multiplied tenfold; or, to make allowance, the single reciprocating propeller of Mr. as he says, for such matters as “extra Booth, however, and the boat with its ten friction, &c.,” say fivefold. Every ves rowers, there is really no analogy what. sel of 100-horses power might at once Mr. Booth proposes to do by one be converted into one of 500, and the stroke what the rowers do by ten, and he Penelope, of 650, now on the stocks, talks as confidently of doing it as if it were might have her unparalleled magni- a thing of the greatest ease imaginable, tude increased to the prodigious amount whereas, in point of fact, it would be of 3250-horses power! You have but found just as difficult to throw the power to adopt Mr. Booth's reciprocating valve of a thousand horses into one pull, as propellers, cam wheels, and pneumatic for ten men to apply their hands to one cylinders, and behold the prodigy achieve oar. Numerous experiments, of unimed!

peachable authority are on record, which But can such things really be ? Can show that it is impracticable to obtain from the true principles of steam navigation one arm or propeller the same degree of have remained so long hidden from the velocity which is obtainable from a numanxious scrutiny of the many eminent ber. What the best numbers are, accordmen who have devoted themselves to ing to different circumstances, such as area their elucidation, that it should have been of floats, power applied, &c., may not reserved to Mr. Booth to pour, all at have been ascertained with perfect exactonce, such a flood of light upon them? ness; but there has been enough, at all Mr. Booth who knows so little of the events, determined, to justify us in proscience of his own particular business, nouncing Mr. Booth's single propeller railway transit, as to suppose that double to be altogether out of the question. Nor power, double speed, is the rule by wbich do we think he will mend his case much, it is regulated ? However possible, it is either by the greater depth or the greater assuredly not very probable.' We do not velocity which he proposes to give to his hesitate to state our own strong impres- propeller, (on the former of which points sion to be, that the whole affair is a delu. he evinces some strange notions,) since sion-very ingeniously conceived, and that would still leave the distribution of most skilfully and plausibly advocated force as it was before, and it is there, but still a delusion. We have not left the fallacy of his system appears to us ourselves room to refute in detail Mr, chiefly to rest,

ever.

of

ON MR, HOULDSWORTH'S PYROMETER BY C. W. WILLIAMS, ESQ. Sir,- I have now to lay before your seems to be dependent on no better ground readers the results obtained from one of than that, practically speaking, we have the simplest, yet most valuable adjuncts none other. This may be admitted as a to a furnace that has yet been applied. reason for its adoption, but can be none So vague have been our modes of testing for its justification, or for our apathy in the comparative values of what are igno searching for a more trustworthy one. rantly called “Smoke Burning" Plans, I am now, however, enabled to state, that, (probably from the want of some that there is a simple and direct mode of thing practically more efficient,) we seem obtaining the desired results, and of testto have quite overlooked the object of ing the boiler and the furnace by rewhich we are in search. Having adopted ference to their respective functions and the boiler, with all its varieties and im modes of action. Let it be understood, perfections, and its fluctuating power that in testing the value of any mode of evaporation, as the instrument for testing constructing or managing a furnace, and the heating powers of the various descrip- particularly as regards the admission of tions of coal, or the efficiency of the se air to the fuel in effecting the most perveral modes of constructing and manag fect combustion, our object is to ascertain ing our furnaces; we thus take one, by which method we obtain or generate and a very imperfect class of vessels, me the largest measure of heat— leaving it chanically considered, as an index of the to another, and different class of exefficiency of a wholly different class, che periments, as to the best means of apmically considered.

plying such heat. In treating of combustion, as regards In a communication made bys me at the use of coal, our object manifestly is, the Victoria Gallery, Manchester, and to to discover the best construction, arrange the Mechanical Section of the British ment and management, of a furnace to Association, I stated, that in pursuing wards obtaining the greatest quantity of the enquiry, on the large scale, as reheat from any given quantity of the fuel. gards combustion, and the modes of proInstead of endeavouring to ascertain this ducing the greatest quantity of heat from measure of heat in the furnace, or flues any given weight of coal, I found it ableading from it, we inconsiderately apply solutely necessary to discard the boiler ourselves to measuring the quantity of in toto-that the uncertainty which exwater evaporated from the boiler placed ists as to the evaporative powers of the over such furnace; and this without the various kinds of boilers in use was such, slightest reference to the good or bad fa that no reliance could be placed on the culty of such boiler, in absorbing and ap results obtained through their means. plying the heat, or even endeavouring to I asked what test, rationally and mechaascertain whether more or less heat is so nically considered, can boilers, with their absorbed, or how much is lost by the peculiar and variable faculties of absorbchimney shaft.

ing heat and generating steam, furnish, Thus, instead of applying ourselves towards ascertaining the proportion of directly to the object of our enquiry, we the furnaces in generating heat, or the refer to a class of secondary, and mani various descriptions of coals in their comfestly uncertain data. So prevalent, in bustible proportions ? And who can dedeed, is this mode of testing the heating termine how much of the heat generated properties of different kinds of coal, or does this or that kind of boiler absorb or arrangements of the furnace, in promot- apply? My eyes were thus opened to ing combustion, by reference to the quan the defective mode of obtaining results, tity of water evaporated by the boiler, by applying the evaporative economy of that we fall into this erroneous practice, a boiler, as a test of the heat-generating and yield ourselves up to a fallacious power of any kind of coal or mode of mode of reasoning and experimenting, managing the furnace. I found a large which would not for a moment be sanc evaporative economy from one kind of tioned in any other mechanical or scien boiler, when combustion was manifestly

imperfect in the furnace, and a great deThis most fallacious test of the che ficiency of evaporation in another, where mical process of combustion by reference combustion was nevertheless complete, to the mechanical process of evaporation, and a much larger measure of heat ob

tific pursuit.

MR. HENRY HOULDSWORTH'S THERMOMETRIC DIAGRAM, SHOWING THE FLUCTUATIONS OF TEMPERATURE IN THE FLUES OF A

BOILER, ON THE NEW AND OLD SYSTEM.

Scale of Temperature in Degrees.

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tained from the fuel. I saw, in fact, that furnace fitted up according to Mr. Wilthe error lay with the boiler, and was liams's patent, by putting three cwt. of forced to the conclusion, that in treating coal upon the fire iwo different times, experimentally of the furnace and its the fire being each time in the same state, management, particularly as regards the and the temperature of the flue, as indiadmission of air, the furnace alone, and cated by the Pyrometer, being in each its heat-generative powers, must be case about 700 degrees. On one occatested, and apart from the boiler.

sion, the air passages were left open, in How then was this heat-generative the other they were closed; in each case economy to be ascertained ? I suggested the experiment was continued for 100 three modes. 1. By means of ther minutes. In the experiment in which mometric bars, the heat being conveyed the passages were left open, the average to the thermometer by the conducting temperature of the flue was about 1,100 power of the metallic bar. 2d. By the degrees; in that in which the passages use of a series of metallic alloys, intro were closed, and Mr. Williams's appaduced into the flues, and which, being ratus thrown out of use, the temperature fusible at varying and ascertained tem averaged only about 900 degrees. During peratures, would indicate the temperature the whole time of the former experiment, existing in the flue. 3d. By means of a there was an entire absence of smoke; pyrometer constructed of a number of during great part of the latter, the flues metallic bars, united by a system of were filled with smoke. Mr. Houldscompound levers, the expansive power worth exhibited a diagram, showing in a of the bars being transferred to an index very striking manner, the results of his placed outside the boilers. These seve- .experiments." I now send you a copy ral modes of ascertaining the internal of the diagram exhibited by Mr. Houldsheat in the flues had their inconveniences, worth on this occasion. (See preceding on which I need not here dwell.

page.) At the late Meeting of the British So sensible was this pyrometer, that it Association in Manchester, Mr. Henry registered the degree of cold produced by Houldsworth described his very simple the mere act of opening the fire door. and useful Pyronieter. He is reported Mr. Houldsworth also stated, that he to have said (see the last number of the tested the effect of admitting or excludMechanics' Magazine, page 32,) that ing the air every five minutes, and on “ he had that morning fitted up a con each occasion the lowering of tempetrivance for ascertaining the comparative rature in the fue by closing the air apertemperature of the flues under different ture was rapidly indicated by the Pyrocircumstances which had not previously meter. A remarkable proof of the rapibeen very satisfactorily ascertained. Mr. dity with which this Pyrometer indicates Williams had used a thermometer, in the change of temperature in the flues, serted in a bar of iron,” (copper,) " which is shown in the diagram. On the charge was placed in the flue; but he (Mr. of 3 cwt. of coal being thrown on the Houldsworth) was not satisfied with that furnace, much carburetted hydrogen gas plan, and had passed a copper wire is of course evolved. If air be so adthrough the flue from one end to the mitted as to effect its combustion, a large other. This was kept in a state of ten fame is instantly produced and a corsion by weights, and by its expansion responding heat. But if the air be exor contraction acted upon an index, cluded, the gas is converted into sinoke, which gave a very correct measure of the and the temperature in the flues rises but relative temperature. He had tried some gradually. These two changes of a sudexperiments with it, and had obtained den elevation of the temperature in the very satisfactory results.”

one case, and a slow one in the other, At a subsequent Meeting of the Asso are strikingly marked in the diagram, ciation, Mr. Houldsworth said, that, from the starting point. So again, when, " Since the discussion on this subject he at the end of 75 minutes, as marked on had made some careful experiments with the first experiment, (see the upper line,) the Pyrometer which he then described ; when the fuel is levelled on the bars and and the results were, in his judgment, the air prevented rushing up in too large exceedingly satisfactory and conclusive. masses, the temperature rises suddenly, These experiments were made upon a above 100 degrees in about two minutes;

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