Scientific American Volume 22, No. 1, January 1, 1870 Part 10

A correspondent, in discussing the causes of fires in flour mills, gives the following facts and queries:

"F. Bertchey's mill, at Milwaukee, burned in September last. The fire originated from a candle held near a bran or feed spout, reaching from the upper to a lower floor. The ignition was instant, and attained different points of the building at about the same moment.

"On November 20, 1868, Schmidt & Co's mill, at St. Louis, burned in a similar manner, the light in this case being in a globe lamp, but the conflagration was, nevertheless, quite as sudden and general as in the first case cited. Other instances of like character have occurred quite recently. And now the query is, What caused the disaster? Whence the combustion?

"It has been conjectured that the bran-dust, or fine and dry powder, pa.s.sing down or up these conductors, may be the kindling cause of the fire in these cases; but bran is not over combustible in itself, nor do we know why it should become so when thus reduced to an impalpable powder.

"Another theory is that a gas arises from the trans.m.u.ting grain, which, excluded from surrounding atmosphere in these close conduits, becomes inflammable, and hence the results, as recited above, whenever a lighted flame is brought in contact therewith.

"Be the cause gas or dust, the disaster is the same: and is it not a phenomenon worth studying and remedying, so far as within the province and control of those most interested?"

Some similar instances came under our personal observation while adjuster for the Aetna at its western branch. The Star Mills at Mascoutah, Ill., burned about the year 1864. They were grinding middlings. About three o'clock in the morning the miller in charge went up to the chamber (a large box extending through several stories), as he had often done before, to jar the middlings down, they having clogged.

He carried a small, open oil lamp, which he placed on a beam, just behind and above his head. He then opened a slide and thrust in a shovel, which started the middlings down with a thump, raising a great dust. As this dust issued in a thin cloud from the slide, it approached and touched the lamp, when instantly, as if it had been coal gas, it flashed, burning the miller's hair and beard, and filling the middlings box with a sheet of flame, which spread with great rapidity and destroyed the mill.

A mill at Dover, Ky., had acc.u.mulated a large quant.i.ty of middlings in an upper story, when the weight caused some sagging, and a man was sent up with a shovel to "even" the bin. His pressure was the "last straw,"

and the floor under the man broke through, pouring out a cascade of middlings, which flowed down from story to story, filling the mill with its dust. In a very few minutes it reached the boiler room, and the instant it touched the fire it ignited with a flash, and the mills was in flames instantly. It was totally destroyed.

In this last named case the gas theory will not apply. The dust was not confined in a spout, but was floating free in the air throughout the mill. The phenomenon was like the others mentioned, and seems to indicate that the fine dust itself, when floating in the air, is the fatal incendiary.

The subject is worthy of a scientific a.n.a.lysis, such as we have never seen bestowed upon it. The facts are well authenticated, but the philosophy of such ignition is not generally understood.--_Insurance Monitor_.

Fire-Proof Buildings.

"It has long been a vexed problem with architects and builders, how to make a building completely fire-proof without the enormous expense of iron beams and girders, and even this has sometimes failed to prove a complete protection. In the building of the National State Bank, the architect estimated that it could not be made fire-proof in the ordinary style for less than $6,000, and while hesitating as to the expense and seeking to provide some remedy against the dampness incident to iron beams, Mr. Fowler learned from the SCIENTIFIC AMERICAN that Edwin May, of Indianapolis, the well-known architect of our county jail, had taken letters patent on a fire-proof lath for ceilings and inside part.i.tion walls, together with a concrete floor for the protection of the upper edge of the joist which by actual test had been demonstrated to be fire-proof. After a critical examination of the invention upon its merits, it was adopted, and the workmen are now engaged in putting it in. Our citizens engaged in, or contemplating building, will be interested in an examination of the work while in progress."

[We copy the above from the _Lafayette_ (Indiana) _Courier_, and in this connection we make the following extract from a letter just received by us from Mr. May, the inventor:

"You will see by the above notice one result of my advertis.e.m.e.nt in the SCIENTIFIC AMERICAN. This is only a _mite_. I have more than I can do, and I would say to inventors who are not realizing what they expected from their patents, that one _ill.u.s.trated advertis.e.m.e.nt_ in the SCIENTIFIC AMERICAN will effect more than a notice in all the newspapers in the United States. This is saying a good deal but such is my belief."]

The Decline of American s.h.i.+pping.

At a meeting of the New York Chamber of Commerce, held December 16, to consider means for reviving American commerce, the following resolutions were adopted:

Resolved, That this Chamber recommend to the Congress of the United States, about to a.s.semble, the modification of existing laws, so that

I. Foreign-built steamers may be imported free of duty, and privileged to carry the American flag, provided they are American owned and not to be employed in our coastwise trade.

II. That iron plates and such other material for the construction of steamers as may be deemed advisable, be admitted free of duty.

III. That on all s.h.i.+p stores procurable in bond, drawback be returned, as upon goods s.h.i.+pped for sale to foreign lands; and

Finally, That ample subsidies be granted to lines of steamers built in American yards, to the end that compet.i.tion with powerful foreign organizations may be successfully inaugurated and sustained.

The Chamber ordered the resolutions engrossed, accompanied by a memorial forwarded to Congress.

These resolutions, in our opinion, embody the solution of the question under consideration, and we trust they may be speedily and favorably acted upon by Congress.

Young men out of employment can easily obtain enough subscribers for the SCIENTIFIC AMERICAN to receive a cash prize of sufficient magnitude to insure them a good salary for six weeks' work. Send for prospectus and circulars.

CORRESPONDENCE.

_The Editors are not responsible for the Opinions expressed by their Correspondents_.

Aerial Navigation--A Suggestion.

Messrs. Editors:--As a constant reader of your invaluable paper, many subjects of deep interest come under my observation, and doubtless no journal throughout the land contains more instructive reading--that which tends to accelerate the progress of scientific investigation, and promote the general interest of the people--than the SCIENTIFIC AMERICAN. The series of articles under the head of "Aerial Navigation,"

commenced on page 309, volume XXI., has, perhaps, been read with as much pleasure and interest as anything published in your valuable journal. I say with pleasure--because it is really gratifying to mark the advancing steps which inventors are making in this branch of science; and with interest--because every new idea set forth, calculated to further the success of aerial navigation, should be, and no doubt will be, regarded as of great importance by every one. And, as the more suggestions placed before the minds of those working for the improvement of any invention, the greater number will they have from which to choose or experiment upon, I would like to make one suggestion here, which may be of some importance in the construction and operation of the "Aeroport," under the supervision of Mr. Porter, of your city, a description of which is given on pages 346-7, volume XXI., of your paper.

I suggest that the propelling wheels be placed in some other position than that given in the said description. From what little knowledge I possess of aerial navigation, I am persuaded that it would take less power to propel the "Aeroport" at a given speed, if the wheels were placed at the rear or front portion of the flying s.h.i.+p. My reason for being thus persuaded is, that as the forward and aft halves of the float are cone-shaped--the center being the base, and the front and rear ends being the vertexes--there must be an increased velocity of the atmosphere from front to aft as the aeroport advances. Consequently the driving wheels being placed under the center or largest diameter of the float, they must evidently revolve with greater rapidity in the current of air pa.s.sing between the float and the saloon, going in opposite direction to that in which the aeroport is flying at a given speed, than they would were they placed in front or behind where the atmosphere is comparatively at rest. I take this view from the fact that steamboats and other vessels proceed with greater speed, with a given power, _down_ stream than they do _up_ stream, mostly on account of the paddles striking against the current flowing in the same direction in which the vessel is rowing. The propelling wheels placed either at the front or rear may have the axle extended through the end of the float to the center, and the cog-wheel, for the chain, placed on the inner end of the axle, and the chain descending through the bottom of the float, and connected to the engine in the same manner as given in your paper. The chain should be inclosed from the float to the saloon below, with a pipe of the same material as the float, and sufficiently large to insure the free action of the chain, and the axle of the propellers should be made tight with suitable packing to prevent the escape of gas. However there may be different arrangements employed for connecting the engine to the wheels. A shaft extending directly under the float, and reaching from the center to the axle supporting the propellers, and connected therewith by means of side cog-wheels, might be used; and as the shaft would necessarily diverge from a straight line with the said axle, the shaft having the chain-wheel on the end directly over the engine and connected therewith in the manner proposed by Mr. Porter, I would suggest further that it would, perhaps, be preferable to place the wheels at the front end, that the rudder might remain in its original position, and the aeroport could swing behind the propellers on encountering side currents of air, and could thus be more easily guided.

I firmly believe that Mr. Porter has taken "the right step in the right direction" to accomplish that which has been so long sought, and which evidently will be accomplished at some future time. The air will yet be navigated by numerous flying s.h.i.+ps, going from one city to another like those that now cover the broad bosom of our oceans.

HIRAM VAN METER.

Macomb, Ill.

Puttying Floors of Jewelers Shops and Otherwise.