412

house on fire presents, is beyond their capability.

The stream of Braithwaite's floating-engine on the Thames is about the bigness of one's arm, and it is said to throw up a ton of water a minute:* here, then, we have an engine of efficient power; but it is only available in cases of fire near the river-side, and then not at low-water,-which was the cause of its not rendering such good service at the fire in question. Deficiency or delay in the supply of water is the common complaint at all fires; and the water-companies also complain of the enormous waste of water, which they allege to be the cause of the deficiency, though it cannot be of the delay. The quantity of water suffered to run down into the sewers, is doubtless more than is used in checking the progress of the flames. Surely there are other methods of supplying an engine with water than by flooding the streets? A pipe screwed on to the main, having branches communicating with the hose of several engines, would convey all the water withdrawn from the reservoir on to the fire; and such an increase of propelling force might be supplied as would project a greater volume of water to the requisite height. Steam power is at present the most available for this purpose; and we used to hear mention made of a steam fire-engine, which performed wonders. What has become of it? The efficacy of a stream of water less than six inches diameter seems to us to be inadequate to the quenching of a mass of fire: if a whole cistern of water could be raised to the requisite height and overturned on the flames, a few repetitions of such a dose might suffice to extinguish them at once, with less labour and a far smaller consumption of water than by the present mode. Should this not be practicable, however, the column of water propelled by the engines ought at least to be greatly increased; and some mode adopted for preventing the waste of water, and securing a prompt supply. When the fire-insurance companies suffer so largely as the Sun is reported to suffer, we may reasonably expect that the Directors, looking to their own interest, will cast about for some better protection from loss, which will benefit the public generally. The first step to an improvement of the fire-police has been effected by adopting the principle of co-operation : it now remains to put an efficient mechanical power into the hands of the Fire Brigade.— Spectator.

The writer labours here under some mistake. Mr. Braithwaite has no floating-engino on the Thames; he did submit to the associated fireoffices the plan of one which would have thrown, not a ton, but a ton and half of water a minuts -to a height of some seventy or eighty feet-but it was declined, for reasons which we must leave the gentlemen whose characters are implicated by the refusal to explain.--ED. M. M.

HINT WHICH WILL BE USEFUL WHEN (?)

MAGNETIC LOCOMOTIVES ARE IN USE..

Sir, I observed in your last monthly Number, among the "Notices," that Mr. Mullins, M. P. for Kerry, was constructing a locomotive-carriage to be propelled by the power of electro-magnetism. If he generates his power by means of the action of diluted sulphuric acid on alternate plates or cylinders of copper and zinc, hydrogen gas is rapidly evolved, which I should advise him to save for the purpose of lighting up the carriage if intended for night travelling. And, again, the zinc and the copper decomposed by the action of the acid would be converted into sulphate of zinc and sulphate of copper, which, if formed in a considerable quantity, would be well worth extracting, and go a long way toward paying the expense of a new generator.

I remain, Sir, yours obediently,
TYRO MECHANICUS.

Chacewater, Sept. 13, 1836.

AVERY'S ROTARY STEAM-ENGINE.*

The re-invention in America of Hero's engine, and the application of so old a principle in the power of steam to useful purposes, has created some stir on this as well as on the other side of the Atlantic. In both the old and new countries have the statements put forth by its re-inventor, Mr. Avery, been met with disbelief and an unfavourable prejudice. These obstacles, however, seem to be gradually diminishing in America, where the engines are becoming, by a sort of reaction, great favourites; according to the American Railroad Journal, "the demand for them is greater than can be supplied, by the constant labour of one hundred men!" One is about to be shipped for the government of Russia, and another for the government of Prussia. Will not some engineer put the thing to a working test in England? From the above-mentioned source (into which they are copied from a pamphlet), we abridge the following testimonials in its favour. In the Railroad Journal, copies of the letters are given verbatim; they have a genuine appearance, and are from known persons, and as such we are

Described in No. 637,

bound to give credence to the statements contained therein.

After describing the rotary engine as working a saw-mill, it is said that,

"Saw-mills of this description are in common use in the western and south western states, driven by Avery's rotary engine, which is now coming much into use, for flouring and saw-mills, cotton-gins, and other purposes, as will be seen by the accompanying extracts of letters to Judge Wilkeson, of Buffalo, who has the agency west of the Lakes and Alleganies. These are only a few of the very numerous letters, which might be published, commendatory of the engine; yet they are, with others herewith given, sufficient to place it in its proper light before the community.

"A candid perusal, and unprejudiced examination of the engine, will satisfy those who desire to be convinced. This engine speaks, by its silence, its own praise, to those whe witness its operation.

"The gentleman, Mr. Kinney, who wrote the letters from which the following extracts are made, resides at Louisville, Ky., and has a machine-shop there, in which the first rotary engine was put up west of Pittsburgh. The engine operated so much to the satisfaction of Mr. Kinney, and his partner, that they undertook the putting up of engines in the south western States.

"It will be observed, that it was with difficulty introduced into use, in the south-west, as there were but few who dare trust their eyes when its operation was so directly in the face of previous theories, and especially whilst every machinist and man of science opposed it."

The principal facts mentioned in Mr. Kinney's letters are as follows:- On the 15th of August he put up an engine for Messrs. E. Grover and Co., of Richmond, which he left in complete and successful operation. He says, "I met with no difficulty the first time I raised the steam in making the engine operate to the entire satisfaction of its owners, and the admiration of multitudes who came to see the far-famed rotary steamengine." On the 23rd of September, he acknowledges the receipt of three engines. One of these, a large one (he does not state the size), he put up at a mill at Shelbyville; and on the 28th of the same month he writes as follows:

"The mill at Shelbyville operates admirably well; I put up the three 18-inch boilers which I received from Pittsburgh, and find that there is a superabundance of power to

413

drive two pair of 3 feet stones, so as to grind wheat or corn, well and fast. I remained two days after they commenced grinding, and left every thing operating to the entire satisfaction of all. Mr. Dupuy was much pleased with the engine, and unhesitatingly paid 400 dollars, and gave good security for the remaining 500 dollars.

"Having all my machinery ready to drive the stones by bands when your plan arrived (to drive them with gear), I could not, without much expense and delay, make the alteration. The large wheel is six feet, its shaft is nine feet long, upon which is a drum, and from which drum-bands pass to pulleys on the spindles which drive the stones; bands also pass from the drum to drive the force and cold water pumps, elevators, bolts, screen, fan, and hopper boy, all of which perform their office well and sufficiently fast to convert 10 bushels of wheat per hour into flour."

On the 13th of November, he acknowledges the receipt of one engine, and mentions the shipping of another. Having erected the former for a Mr. Henry, he says,

"Mr. Henry's engine is in successful operation. He is fully satisfied with its performance, so far as he has had an opportu. nity of testing it. ** I have put two run of 3 feet stones in operation for him, and believe the power is sufficient for three run of 3 feet, or even 4 feet. I put up three boilers 20 feet long and 22 inches diameter, say exactly by that size. More pains should be taken to have the large engines accurately balanced, and the pulley also should be put on the shaft before the arms are, and exactly balanced-if the pulley is not balanced, it produces a vibration between the end of the shaft and the centre, against which it runs. I am more pleased with the operations of all parts of this engine than any rotary I have yet put up; and I believe it will be so managed, by those who have the care of it, that it will continue to perform well. **The stones have 135 revolutions per minute, and grind at the rate of seven bushels per hour."

In February, in the present year, Mr. Kinney states,

66 I have put in operation for Judge M'Ghee two cotton-gins and one pair of mill-stones 3 feet diameter, and I find that the engine has an abundance of power, although I have been under the necessity of using very poor wood, but have no doubt that if I had another cotton-gin to put on, it would drive the three, with the mill. The boiler is 23 feet long, and 26 inches diameter. I expect to attach to this engine a saw mill-saw, as

414

the power is sufficient. This engine has three feet arms."

In various letters, engines are spoken of favourably, as working at different mills, upon a railroad (of which no particulars are given), and in a boat. Certificates also, with numerous signatures, attest its successful operation; that it is the best engine for milling purposes,the easiest of management, &c.; and this after two and three years experience of its working.

Messrs. Lynds and Son, of Syracuse, engine manufacturers, having put up one for a saw mill, for a Mr. N. Felt, addressed to him the following queries :

"1st. Have you made any alterations in your boiler, in any form or manner, since putting the rotary in use, so as to afford more steam with less fuel?

"2nd. Is there any difference in the amount of fuel required to perform an equal amount of labour with either of the engines? If so, which requires the least, and what is the difference in the quantity used?

"3rd. Does the rotary engine do more or less work, in the same time, than the piston engine? What is the amount of difference?

"4th. Which engine do you conceive to be the most simple in its construction, and in its application to any mechanical purpose the most natural? Also, which is kept in repair with the least expense?

Mr. Felt returned the following Answers: "In answer to your first question, I would say I have made no alteration in my boilers or arches.

"2nd. As to the amount of fuel required, I am not able to answer precisely, but am sure the rotary does not require more than two-thirds the quantity to put it in operation the piston engine required.

"As to the amount of the business performed, the rotary will do double the amount of the piston engine in the same time. So far as I am acquainted with the two engines, I consider the rotary the most simple in its construction and application to mechanical purposes, and I think is kept in order with the least expense. With the experience I have with the two engines, I should prefer the rotary for any mechanical purposes whatever."

Dr. Jones, the editor of the Franklin Journal, to whose pages we are so frequently indebted, and in whose judgment we place great confidence, gives some very favourable testimony in re

lation to Avery's engine. We subjoin what he says, therefore, as an answer to the various correspondents who have asked us for further information, or our opinion, upon the subject. The remarks appended are from the Franklin Journal, and are given in answer to a correspondent signing "Fair Play" :

"It so happens that 'Fair Play,' and others, who desire information on the subject of Foster and Avery's re-acting steamengine (commonly called Avery's), will, in the present number,* have a full opportunity of seeing what constitutes the claim of these gentlemen to a patent for an improvement in this machine. They were fully informed respecting what had been attempted with engines similar in construction to their own, previously to their obtaining a patent; and it will be seen that they have confined their claim to improvement within very narrow limits, and so far as we are informed, their claim is a valid one. It may be said that their improvement is trifling; that, however, is their own concern, as those who do not need it are at full liberty to use the machine in any of the various forms which had been previously given to it, or to devise others which are new, without buying from them what may be deemed unimportant.

"We are not sufficiently well informed respecting the comparative results obtained from Avery's and the reciprocating, or Avery's and other rotary engines, to make up our minds respecting its real value. Between four and five years, however, have elapsed since this engine was patented, and it has been at work at Syracuse, and various other places, during the whole of that time, so that those who have seen it, and who possess a competent knowledge of the subject, have had time enough to investigate it. Before the patent was obtained, we expressed to Mr. Avery our general want of confidence in the real value of such engines, and our doubts respecting the importance of the improve ments claimed; and we did not suppose that the career of the one in question would extend to two years; a length of life greater than has usually fallen to the lot of rotary engines; it still lives, however, maugre our anticipations, and all the reports which we have received relating to it, tend to show that it has not yet exhibited the first symptoms of decline."

The following extract from the specification shows the claim of the patentees :

See extract from the specification annexed.

"We find it to be a point of great importance to give such a form to the revolving arms, as shall subject them to the least possible resistance from the air; we therefore, instead of making them in the form of round tubes, which has been heretofore done, give to them the form which results from making each half of the arm a segment of a large circle, so that, when the two halves are united, the edges of the tube present acute angles. The tubes, however, may be made elliptical, or oval, and the same end will be, in a great measure, attained. We use any number of such arms on the same shaft, as we may find best adapted to our purpose.

"We do not claim to be the inventors of the re-acting steam engine, nor of the case, or drum, within which we intend the arms shall, in general, revolve; but what we claim as our invention, is simply the giving the oblate, or flat, form to the revolving arms, so that, in proportion to their capacity, they shall experience much less resistance from the air than that to which they have been heretofore subjected, thereby obtaining a greatly increased power."

"In several articles published in other papers alluding to Avery's rotary-engine,' information has been asked for; and in order to give an answer as satisfactory as possible, I made personal examination and frequent inquiry of gentlemen of intelligence and character in this city, who are perfectly familiar with the daily operation of one of them with 30 inch arms, or five feet sweep, and thei followng is the result of my investigation; and for its correctness I can give the most satisfactory testimony if desired :

"The engine alluded to is now, and has been for several months, in operation in Attourney-street, in this city-where it has been visited by hundreds of intelligent gentlemen, who have been not only delighted, but astonished at its performance—and especially with its quiet and modest behaviour

if I may so speak. It is not uncommon for gentlemen unacquainted with its appearance to go into the engine-room at the Astor House, where there is one of eight-horse power, after looking at the boiler, pump, and machinery, inquire for the engine-notwithstanding they may be within a few feet of it in full operation. There is nothing in its appearance which indicates a steam-engine; and in the cost of repairs and attendance there is very little more resemblance.

"It will be observed, that a statement is given in the following extract from the (American) Mechanics' Magazine, of the quantity of water evaporated; and it may be proper for me to say that that result was

415

arrived at after repeated and frequent measurements I may also say that the result has since been even more satisfactory-the work having been done with an average of 35 gallons of water per hour-a result very different from what is usually estimated to be required for a piston engine. The estimate is, if I am not in error, from 7 to 9 gallons per hour per horse-power. Allowing these statements to be correct-and they are susceptible of the most satisfactory proof,-it does not require very profound wisdom to arrive at the conclusion that a less quantity of fuel, as well as of water, is used for the rotary than for the piston engine. Should it be also found, on inquiry, that the economy is equally great in the first outlay and in the cost of repairs and attendance, as it appears, by the above to be in the use of water and fuel, there can be little doubt of its coming, and immediately too, into general use. That such is the fact I am prepared to show to those who desire farther information.

"The arms of the engine are 30 inches long from the centre of the shaft to the apertures, and the apertures are each the

of a square inch-they are enclosed in a circular cast-iron case-the shaft receiving the steam at one end, and having a pulley for the main band on the other.

"The following machines are all attached to, and operated by it, viz. :

"I upright saw with 30-inch stroke, or 15-inch crank-averaging 110 strokes per minute.

"1 buz saw, 24-inch, cutting a kerf of of an inch, with 22 to 2400 revolutions per minute.

66

66 66

"3 24-inch circular veneering saws. "126 "127" varying from 12 to 1500 revolutions per minute. "115-inch buz saw, with 1200 revolutions per minute; and

"I whip saw for curves, with 9-inch sweep and 250 strokes per minute. "I grindstone.

"1 blower for the furnace. "And the pump raising water 30 feet into a reservoir for its own use.

"These machines are not always all at work at the same time--as some of them require repairing, or filing, or they are taking off or putting on logs; but this may be said without fear of contradiction-they can all be driven at the same time by the engine now in use, for 10, 12, or any number of hours that the superintendent and hands can tend it; and that, too, with the evaporation of an average not to exceed 40 gallons of water per hour.

"The boiler now in use was made for a

416

"But to avoid over-estimates, we will put the whole at 15-horse power, to accomplish which 40 gallons of water were evaporated at an expense of fuel of one dollar for every ten working hours, and 1 dollar 25 cents for attendance on the engine and fire.

"It should be borne in mind that these saws are all used in sawing mahogany-except the whip-saw, which is used for sawing all kinds of timber.

"In addition to the above, a turning-lathe is to be put in operation in a few days." The following letter we extract in full on account of the interesting particulars it contains, with respect to the mode of operation in obtaining gold from the ore, as well as in relation to the engine. The writer is a Mr. Harris, superintendent of a gold mine, of Charlotte, Mechlenburgh Co., N. C. The letter is dated July 12th, 1836, and is addressed to Mr. Minor, of the Railroad Journal:

"Your note containing questions respecting the rotary engine has been duly received, therefore in compliance with your request I transmit to you the following answers:

"1st. The diameter of the engine, or length of arm, is 5 feet.

2nd. Its estimated capacity or power, was considered by the maker to be equal to twenty horses, which power it has generally performed since it has been in full operation, so considered by myself as well as others employed at the establishment. I am not prepared to say what power the engine would be, by an additional pressure of steam, but the highest pressure used by us, never exceeds 100 lbs. per square inch in the boilers, and frequently not over 80 lbs.

3rd. The machinery and apparatus used are of a very complex character,-six Chil

·lian mills, two Arrestres, one Hungarian washing-machine, four shakers (making two sets of shaking-tables), and one pump of six inches diameter, 110 feet in length, are the various kinds of machinery used and set in motion by the rotary engine. Perhaps a brief description of the nature of the machinery will better enable you to judge of the power required to propel such machinery. The Chillian mill is much on the same principle as that of a Bark mill; consisting of a large stone 6 feet in diameter, and 14 inches thick, which is made to revolve in a vertical position in a circle of 4 feet diameter, which circle is enclosed by staves in the form of a tub, and made so as to contain water; the ore is therefore regularly deposited by means of a shovel under the vertical stones, which revolve, crush the ore, and pulverise it to a powder, when it is carried off, by a constant stream of water passing through the tubs. Much depends on the attention paid, and the character of the ore ground in this kind of mill, as respects the power required to propel them. At our establishment they have always been considered equal to one and a half horse power each. The Arrestre mill differs in its construction and mode of operation from the Chillian mill. It consists, in the first place, of a large bed of solid granite rock, generally about 9 feet diameter, and from 12 to 18 inches thick, encircled by staves which form a complete tub, in the centre of which is placed a perpendicular shaft, and through which, about two feet from the bottom of the tub, pass two horizontal arms, extending the diameter of the tub; to these arms are suspended from four to six large rocks that will generally weigh from 200 to 300 pounds each, when the whole is set in motion by gearing-wheels from the top, and propelled to the speed of about ten revolutions per minute, and the ore mixed with water is pulverised to the consistence of paste. This process, as well as the one described above, depends much on the manner in which it is treated, and the character of the ore, as respects the power required, which has been considered at our establishment equal to 3-horse power each mill. The other apparatus used for washing, &c., require but Jittle power, and therefore need no description. The pump is calculated to raise about 67 gallons of water per minute, with the present number and length of stroke, which, together with the washing apparatus, is considered to require about 5-horse power, making altogether, according to calculation, 20-horse power.

"4th. The engine, since its erection, has been kept in constant operation, Sundays and accidents excepted.

"5th. When in full operation, as all the