Ditto, ditto, square feet surface of all the paddles immersed

Ditto, ditto, number of horses power Each square foot of the actual midship sectional area of the vessel immersed requires, in order to propel it through the water, the following number of cubic feet of steam, at 25 lbs. absolute pressure, to be consumed in one minute. Ditto, ditto, square feet surface of all the paddles immersed Ditto, ditto, number of horses power Square feet of dynamical resisting surface of the vessel propelled by each square foot of paddle-boards immersed Square feet of surface of all the paddles required to be immersed for each horse power

Dynamical number, or work done by cach vessel Each square foot of the dynamical resisting surface of the vessel requires, in order to propel it through the water, the following number of cubic feet of steam, at 25 lbs. absolute pressure, to be consumed in one minute Ditto, ditto, lbs. of coal to be consumed in 14 hours, including stoppages

......

35.900

111.

80.9

119.2

119.2

123.1

183.3

........

Square feet of the dynamical resisting surface of the vessel per horse power

1.103

0.795

0.922

0.904

1.009

0.946

0.882

Square feet of the actual midship sectional area of the vessel

immersed in the water, per horse power

1.035

0.747

0.857

0.849

0.948

0.894

0.838

placement (exterior surface of the vessel immersed in the water) make in the water is compared with the resistance which the same area would experience if moved perpendicularly in the water, at the same depth for each vessel.

2. Dynamical resisting surface, is composed of the midship sectional area and friction of exterior surface of the vessel, being the actual measurement of resistance (reaction from the water) for the vessel, and power of the steam-engine.

When, therefore, the dynamical resisting surface is multiplied by the cube of velocity, in each case, the product gives the relative dynamical resistance of the vessel, or, what is the same thing, the comparative force exerted by the steam-engines in order to propel the vessels through the water. The dynamical numbers for each of the vessels are then as stated in the accompanying Supplementary Table.

When some farther improvements are perfected which I have in progress, I entertain a confident expectation of being able to carry the advantages of the expansion system still farther than have been done in the Era-to the extent, in all probability, of one-fourth more of actual duty performed.

I remain, Sir, your obedient servant, H. ZANDER. Chelsea, October 19, 1842.

THE CHEMICAL PRINCIPLES OF COMBUSTION ASSERTED AGAINST THE MECHANICAL ABSURDITIES OF MR. SAMUEL HALL. BY C. W. WILLIAMS, ESQ. Sir, In a recent communication of Mr. S. Hall, to the " Mining Journal," he seeks to disparage those chemical principles which I have taken as my guide in the admission of air to furnaces, and on which I rely for producing a more perfect combustion of the gaseous matter from coal. These principles, although emanating directly from the writings of Davy and Dalton, Mr. Hall, nevertheless, has characterized as "Fudge." Involving, however, as they do, considerations of public interest, it is worth inquiring what those principles are? what support they have from high chemical authority? and what are their direct bearings on the subject of combustion, practically considered?

an "

Again, as Mr. Hall has charged me with overweening vanity" in this matter, I am desirous of submitting to the public the grounds on which my pretensions, as a patentee, are based. This is done in a few

words. In my inquiry respecting the combustion of the gaseous matter from coal, I had to compare the effects produced by the coal gas when issuing from a single large orifice, or when it issued from the fourteen orifices of the argand burner. I perceived that the greater perfection of combustion which the argand lamp exhibited was directly occasioned by the more numerous, and therefore enlarged surfaces for contact, which the jets presented; "in the same way," as Dr. Brett observes, "as the surface of any given volume of water is increased by causing it to pass, in thin streams, through numerous apertures."

66

My first view, therefore, towards effecting a more perfect combustion of the gas generated in furnaces was, to imitate the principle of the argand burner, namely, the bringing the combustible gas in the form of jets to the atmospheric air. I was soon, however, compelled to reject this mode of proceeding, as I found, according to the reasoning and practice of Sir H. Davy, (and which led to the discovery of his safetylamp,) that the heated gases were soon brought below the temperature of ignition, by the cooling effect of passing through small apertures; and that their combustion was thereby prevented, as when a wire gauze is held over the flame of ignited gas.

Under these circumstances, I almost despaired of carrying the principle of the argand burner into the furnace; chemistry, however, came to my aid, and enabled me to effect my purpose. Observing the con

ditions under which chemical action is induced, and combustion effected, I concluded on reducing to practice the principle which chemistry alone could have taught, namely, that combustion would be equally effective and energetic, whether the combustible be brought by jets to the supporter, or the supporter to the combustible. Following out this principle, it was to be expected that the effect would be the same, if, instead of bringing the furnace gases in jets to the air, I reversed the process, and brought the air in jets to those gases. The first attempt proved that the principle was equally applicable on the large scale of the furnace, as the small scale of the laboratory lamp, and my success was complete. This, then, became the subject of my patent. After many experiments, I found that the sole conditions of success were, 1. That the combustible gas should be brought to the high temperature required for chemical action and union with oxygen; and, 2. That either one or the other-the gas or the air-be introduced in the way of jets; this principle of jets being the only means of effecting that sudden and surface contact between the gas and the air,

which is the sine qua non of their union and combustion, where time cannot be allowed for the more deliberate and true Daltonian diffusion.

In practice, then, and for the first time, the fact was illustrated on the large scale, that "combustible" and "supporter of combustion" were convertible terms; and that jets of air introduced to the gas, or jets of gas to the air, had equally the effect and appearance of jets of flame.

Here, then, is the extent of my claim to a patent. To this Dr. Kane refers, when he pays me the high compliment of saying,

the value of this, although obscurely felt by others, from the imperfection of the older methods, has been certainly first placed in its important and just aspect by your illustrations." Here is the practical application of a well-known chemical principle in the combustion of gaseous bodies. It is not the introducing the air in this place, or that place, (and in what place has not the air been introduced by some inventor or other?) but the mode of introducing it; and they who dispute my principle, or the value of my mode, must be prepared to say that there is no difference, in effect, between the argand burner and the single large jet. Here, then, is my claim on the score of "invention," as it is termed in patent law. To this alone does my "overweening vanity" extend.

In the course of my experiments I became convinced of the all-commanding importance of raising the temperature of the gases in the furnace before bringing them into contact with the air; and that, provided these conditions of numerous jets on the one hand, and high temperature on the other, were satisfied, it was immaterial, in practice, how large the scale of operations might be -in what place the jets were introduced; whether they began at the bridge, or at intervals of ten, or even twenty feet distant. The principle on which I relied is, however, so clearly enunciated in the following extracts from the opinions of Professor Brande and others, that I here quote them, as the best reply to Mr. Hall's "Fudge."

Professor Brande observes-" you admit a number of jets of air into a heated inflammable atmosphere, and so attain its combustion in such a way as to produce a great increase of heat." Again" In this way each jet of air which you admit becomes, as it were, the source or centre of a separate flame; and the effect is exactly that of so many jets of inflammable or coal gas ignited in the air only, in your furnace, you invert the ordinary state of things, and use a jet of air thrown into an atmosphere of inflam

mable gas; thus making an experiment upon a large and practical scale, which I have often made on a small and theoretical one, in illustration of the inaccuracy of the common terms of combustible, and supporter of combustion, as ordinarily applied." Mr. Brande then adds "I have no hesitation in saying, that the views promulgated in your essay are substantially founded upon just and scientific principles." After such a testimonial, may I not almost be censured for noticing such cavillers as Mr. Hall, who can look at these views and principles as "Fudge?" Respect for myself, however, and respect for the public, who have a right to examine the claims of every man who seeks to have his opinion received, has alone induced me to make this communication.

I might here enumerate many such testimonials from men of high standing, but will content myself with the following extracts from deliberately-written and elaborate examinations, both of my treatise, and the principles on which my mode of admitting air is based. Dr. Ure observes-" In case of great steam-boiler furnaces, for which your patent is especially intended, your plan of distributing atmospheric air in a regulated quantity, by numerous jets, through the body of gasiform matter, is peculiarly happy; and must enable you to extract the whole heat which the combustible is capable of affording." Dr. Brett, of the Royal Institution, Liverpool, says-" By causing the atmospheric air to be drawn by jets among the inflammable gases, you employ, as it appears to me, the only means practicable, in operations on a large scale, of causing a sufficient mechanical admixture between the air and the gases to be burnt. By such means you considerably extend the surface of any given bulk of atmospheric air admitted, in the same way as the surface of any given volume of water is increased by causing it to pass in thin streams through a vessel containing numerous apertures." Again, the old mode of combustion in furnaces is manifestly incompetent to effect this perfect combustion, which is only to be obtained, in my opinion, by a plan based upon such principles as you have advocated." Dr. Kane observes, 66 The introduction of air at the bridge and along the flame bed, to supply the quantity of oxygen necessary for the combustion of the volatile products of the coal- the diffusion of this air, secured by its issuing from a great number of small jets, and the consequent full combustion of the gaseous fuel, are elements of real economy and success in practice. The value of this, although obscurely felt by others, from the imperfection of the older methods, has

been certainly first placed in its important and just aspect by your illustrations.”

These, I repeat, are the principles on which my claim to the attention of practical or scientific men is based-these are the bounds by which my "overweening vanity" is circumscribed.

But, I ask Mr. Hall, will he explain the principles (if he have any) on which he expects to produce a more perfect combustion than any other patentee? for surely he has no right, on his mere ipse dixit, to expect that all the world will yield to his mere assertion, and particularly, on so difficult a subject as combustion.

Now, to bring Mr. Hall, and his invention to a practical test, I ask him to satisfy the public on the following points:-1st, On what principles does he expect a more perfect combustion in steam boiler furnaces, by the use of hot, rather than cold air, when unaccompanied by the blast; for such is not advocated by any chemical authority? 2nd, On what principle does he rely, when he introduces this hot air at the front end of the furnace and near the door, rather than at the back end, as done by Mr. Coad? 3rd, On what principle does he rely for increasing the quantity of oxygen in a furnace, by heating the air which is to supply such oxygen -seeing that every well-informed chemist tells us, that the hotter the air is made, the less oxygen will be introduced? 4th, On what principle does he rely for preferring to burn the smoke, rather than the gas, from which the smoke is generated, by some imperfection in the process?

To common minds, it appears a more common sense proceeding, to burn the gas, in the first instance, by a perfect process, (as we do in the Argand burner,) rather than adopting the round-about measure of, first, making the smoke, and then endeavouring to burn it. Until these questions are answered, clearly and explicitly, (and which, I guess, he will be rather slow in doing,) Mr. Hall is not justified in expecting that his mere dictum is to pass for authority; or in charging the principles of others as "fudge."

I am, Sir, yours, &c.

C. W. WILLIAMS. Liverpool, October 17, 1842.

PURE WATER V. IMPURE CISTERNS.

Sir,-In bringing this discussion to a close, I beg to offer a few additional remarks, and, in the first place, to our "old friend Cole," who, it seems, must needs have a brush with me, and brings forward such sweeping arguments, that the Atlantic itself might well re

coil from his sturdy besom. Mr. Cole states (as a fact) at page 333, that the water as it comes from the main is so thick as to be unfit to drink, or to use in the preparation of food"-and thence he argues the inutility of occasionally cleansing our cisterns. If his statement had any foundation in truth, it would rather go to enforce the necessity of adopting this precaution. I will,

in return for Mr. Cole's, also mention a fact, which is, that where the daily supply of water is drawn direct from the main, without the intervention of cisternage, better and purer water is generally obtained than where filtration by deposition within a cistern takes place-neutralized, as it too often is, by admixture with a mass of accumulated impurities. The only exception to this rule occurs during the prevalence of heavy rains and floods.

The improvement in cisterns suggested by Mr. Cole at the close of his letter is too good to give away-it must be patented.

My doughty antagonist "B.," having closed his case, a few words in reply will dispose of him; for I think it can hardly have escaped the notice of any attentive reader, that "B." has most studiously avoided the only point upon which he professed to join issue with me-viz., the state of the water as supplied by the London Companies! The whole of his last lost labour was to have proved two things-Firstly, "that impure water was injurious to health and to life;" a proposition which, I apprehend, no sensible person would ever attempt to dispute. I certainly never did; on the contrary, in my opening paper I gave a striking proof of the fact from my own personal observation. This proposition I hold to be incontrovertible, and therefore think the evidence adduced in support of it altogether superfluous.

The second proposition was, "that the water, particularly as supplied by the London Companies, is impure, and a primary cause of the augmenting mortality of the metropolis." To support this proposition, extracts are brought forward, from the evidence of medical men and others; but it will be seen that they are all out of court-not one single evidence relating to the fact sought to be established. Not one of these parties speaks to the quality of the water as supplied! The greater portion of the remarks refer generally to the water as used—i. e., as drawn from filthy cisterns; and not as supplied. Other extracts relate to water taken from the Thames close to the mouth of common sewers, and in some cases (to ensure the desired results) from the sewers themselves. Sir John Hall is made to illustrate the quality of the water as supplied, by

speaking to that of the stagnant water in the St. Katharine's Docks!" Oh fie! Mr. "B.," call you this" honest-ay, honest?"

46

That the water, as supplied, is impure to the extent assumed (the injury of health and cause of death) I have already given a denial; its impurity, in a qualified sense, I willingly admit. To the latter limb of the proposition I merely reply, that, as no augmenting mortality of the metropolis" exists, the attempt to ascribe an effect, which has no existence, to any particular cause, is truly absurd. The health of the metropolis, like that of all other towns, fluctuates with the seasons, and therefore must be attributed to general and not to local causes. The insinuation may be ingenious, but it is assuredly unjust.

The effect produced upon the milliners' girls, and attributed to their drinking impure water,* might be referred solely to the filthiness of the water butt—or with much greater propriety, to the sedentary nature of their employment, and the impure and unwholesome atmosphere in which the "female slaves of England" usually labour; the effects of which, in producing "pallid faces" as well as aching heads and hearts, are, alas! too well known.

Going "out of town for a few days," affording, as it does, relaxation from mental and bodily labour, change of air and scene, would produce a beneficial effect upon persons engaged in much less unwholesome employments than that of "milliners' girls❞— leaving change of water (which is not always for the best) entirely out of the question.

But a drowning man will catch at a straw, and "B." must have been sadly at a loss for proofs when such lame cases as these are brought forward. They are quite out of place in a practical and scientific discussion; as are likewise the quoted expressions of a noble lord, who is represented to have said, "that he would not take a bath in the water as supplied to him, much less drink it." The noble lord's expression is no proof whatever, either of the goodness or the badness of the water; if true, it is merely a proof of his lordship's effeminate fastidiousness, and I pity him. If " Alexander the Great" prefers a bath of double distilled lavender water, and his means can compass such a luxury, in the name of all that's delightful let him have it, and welcome-"every one to his liking."

And yet, I fancy ere this noble lord gained any laurels in America-or ever smoked

If their employer was as anxious about their welfare as he pretends, could he not have supplied them with a moderate quantity of some more generous drink?

his first puff with brother Jonathan, he did actually gulp down some of this much-abused "compound;" for I believe the ship that carried him out was not provided with a store of Stuckeyfied water* for his lordship's private use. As for "B.'s" "raw head and bloody bones" stories about "poison water," he must tell them to the marines, the sailors won't believe him; and who, after all, are better judges of fresh water than the sailors? Ask Jack where he gets the best water, and where he takes care to ship the largest quantity that he can carry-he will tell you, "in the Thames!"

Numerous as have been my contributions to your pages, I remember none that has been received as was my first on this subject: I have received numberless thanks for calling the attention of parties to a matter which had so entirely escaped their notice, and I know that there has been more "cistern cleaning" going on during the last month, than London ever saw in twelve months before. What may be the ultimate result of this discussion I know not, but its present effect has been (as intended) extremely beneficial, and in taking leave of the subject, I beg to submit the following practical deductions, leaving each person to apply them as seems best for his particular object.

1. The water stock of the Londoners is impure.

2. The sources of impurity are two-fold, viz., Firstly, The impurities supplied with the water by the water companies. Secondly, The impurities which enter the cistern and become mixed with the former.

3. The remedy for the first of these impurities, rests entirely with the water companies.

4. The second source of impurity is within the power of every housekeeper materially to diminish, in two ways: - Firstly, By closing up all those apertures through which a great variety of animal and vegetable matters now find ready access to our cisterns. Secondly, By occasionally (say two or three times a year) clearing the cistern of all those impurities, which, in spite of every precaution will be deposited, let the state of the water as supplied be what it may.. I remain, Sir, yours respectfully, WM. BADDELEY.

29, Alfred-street, Islington. October 13, 1842.

I beg Mr. Stuckey's pardon, I mean no offence, to him; the expression originated with the man of bristles, and it comes in rather apropos just now. + If I were making an Almanack I would put down against the last day in the months of March, June, and September," To preserve health, clean out your cisterns and water butts."