mention of pipe-veins, I applied through a friend to the School itself, and received from one of the officers of its Museum of Practical Geology the reply, that the model contains "no indications of pipeveins." This is positive evidence of the subordinate character of the pipes of ore.

Similar testimony is given by Prof. L. Moissenet, of the Paris Ecole des Mines (Observations on the Rich Parts of the Lodes of Cornwall, etc. Translated by J. H. Collins, F.G.S. London, 1877), who says (p. 2) of the lead-veins of the mountain limestone-the same as Wallace discusses-"To these lodes the pipe-veins and flats are attached; these are accessory deposits occurring in some of the limestone beds." (Italics mine.) Again, speaking (p. 10) of the ore-deposits of Cornwall, he says: "Floors and carbonas are accessory deposits. . . . The floors are analogous in structure to the 'flats' of the lead mines of carboniferous limestone. . . . The carbonas are rich masses of tin ore occurring in granite, the true equivalents of the pipe-veins of the North of England. . . . Mr. Henwood has described how they are related to the lodes."

Vague reference having been made by some advocates of the independent character of pipe-veins to the occurrence of such veins in Cornwall, and a paper by Dr. Clement Le Neve Foster, the Royal Inspector of Mines for that district, having been alluded to as authority, I attempted to verify this reference. In my collection of Dr. Foster's writings, which are everywhere recognized as among the most trustworthy and important contributions of the present generation to the science of mineral veins, I could find nothing to warrant this citation of him. Prof. Moissenet says in a footnote (p. 10): "Deposits of tin ore resembling pipe-veins occur at East Wheal Lovell, in Wendron, and were described in a paper read to the Royal Geological Society of Cornwall, in 1875, by Dr. C. Le Neve Foster." This paper does not bear out the conclusions sought to be drawn; and to make sure that there was not some other to which the reference might have applied, I wrote to Dr. Foster, and received from him several letters, setting forth his views on the veins of Cornwall with much clearness and force. I take the liberty of quoting a few sentences immediately concerning the point now under consideration:

"The paper referred to . . . was probably one I read about two years ago on East Lovell Mine. I send you a copy by this post. I have not used the term 'pipe-vein.' I merely called some of the ore-bodies pipes.' I have used the word 'pipe' to designate a long, narrow ore-body, a narrow shoot (or 'chute,' as

you write it) of ore, in fact. ... All the pipes' at East Lovell are merely altered granite on the sides of fissures; and I am coming round to the opinion that most Cornish tin mines in granite are merely bands of altered rock. ... The carbonas of Cornwall, which are supposed to correspond to pipe-veins, are merely altered granite. . . The carbona is a mass of stan niferous schorl-rock formed by the alteration of granite. It is not a large chamber in the granite, subsequently filled by minerals. .. I doubt whether the carbonas are the equivalent of the pipe-veins. I have never seen a true pipe-vein in limestone myself, so cannot speak authoritatively."

Having examined all the authorities cited by those who assert that pipe-veins, as hitherto known in literature, are independent ore-deposits, I am led to conclude that this view is not fairly deducible from anything that has been quoted in its favor. Whatever may have been anciently believed, it is now clear that the term pipe-vein applies only to an ore-body of a certain shape, which may be part of a fissure-vein, a bed, or a stockwork.

The question remains, whether this name should be revived, and applied, either (1), as some have proposed, to ore-deposits in which the ore has ascended "through pipes instead of fissures," or (2), as others have proposed, to fissure or other veins, in which elongated bodies of ore occur. To this I would say, in general reply, that the revival of an old name for a new thing is objectionable, and unnecessary. But there is no new thing presented. The three chief mines in the United States which have lately received this name at the hands of some are, the Emma in Utah, the Richmond in Nevada, and the Union at Cerro Gordo, California. Neither of these is a pipe-vein in the old sense, though each of them may contain, as subordinate interior features, a great many pipe-veins. It is much better to class them geologically as metalliferous beds, containing, if you please, pipes, chimneys, chambers, strings, and what not, of ore. A new name for this class of ore-deposits might indeed be convenient, not because they are not well known already, for the greater part of the lead product of the world is derived from just such deposits, but because the present names do not briefly and clearly define them. Yet the name of pipe-vein would be no relief. It might apply to one of the deposits of this class, by reason of the shape of the orebodies, and fail for the same reason to fit another deposit of the same class, or another part of the same deposit. The notion that oredeposits exist, in which "pipes," apart from fissures, have been conduits for ascending solutions or sublimations, lacks proof.

The most mischievous result of such a nomenclature would be its legal effect, if our courts were not too wise to permit it to influence

their construction of the law. Title, under the United States Mining Law, is referred to the strike and dip of the veins claimed, and it is universally understood that the strike and dip must be taken at right angles to each other. But in the famous Eureka-Richmond Case, a distinguished advocate, himself a mining expert, arguing that the Richmond ore-body was a "pipe-vein," declared that the dip of such a body "is the inclination at which it enters the earth. When you follow the body of ore downward into the earth, you are following it on its dip. And you may call the direction at which it enters the earth by any name that you like; you cannot divest it of that name. That applies to it, no matter whether it be also the course or not." (Argument of Hon. Thomas Wren, p. 31.) This confusion of strike and dip would naturally result from applying the terms to a deposit, the horizontal section of which shows no principal, longest axis. It might be troublesome to ascertain the strike of a stock work or mass. But nothing would give quite as much trouble as a "pipe," the dip of which, if taken by itself as an independent body, might be plausibly urged to be the same as its pitch-or, in plain words, "it dips wherever it goes." On the whole, therefore, it seems best not to erect such an ore-body into a new class. Let the "pipe" be an ore-body, and give to the deposit containing it and its associated bodies such a name as the facts will justify.

IRON MANUFACTURE IN MEXICO.

BY J. P. CARSON, NEW YORK CITY.

(Read at the Wilkes-Barre Meeting, May, 1877.)

THE works of the Tula Iron Company are in the Republic of Mexico, State of Jalisco, twenty-eight leagues southwest of Guadalajara, ten leagues northwest of the town of Sayula, through which passes the projected line of the Mexican National Railroad. Its geographical position would be about: latitude, 20° 10' N., longitude, 4° 35′ W. of Mexico City. The surrounding country is a rolling plateau, 6000 feet above the sea, enjoying the most magnificent climate in the world, the average temperature being about 70°.

The works were commenced in 1850 by a company with very small capital, having not the least idea of the undertaking. They soon fell into the hands of the money-lenders, and after changing

owners three times, the works came, in 1870, into the possession of the present company, and have been in a manner rebuilt. As they were originally commenced without any fixed plan, and each successive owner has pulled down and rebuilt according to his fancy, the result is a number of old machines and sheds, huddled together in the most inconvenient manner, which have cost about four times as much as an entirely new establishment.

DESCRIPTION OF THE WORKS.

Water-power.-Being placed at the junction of two synclinal valleys, Atunajac on the north and Tapalpa on the south, the direct drainage of thirty square miles is partially received; and for a trifling amount expended in straightening and removing the obstructions of the various water-courses, the amount of water in the dryest season (the month of May), which is now 3.6 cubic feet per second, may be doubled. The rainy season commences in June and ends in October. The present dam collects sufficient water to last until the end of April, or about ten months, more or less. This dam is of rubble masonry, built in form of an L, across the valley. It is 650 feet long and 20 feet high at the highest point. Here it is 7 feet at the base and 33 feet at the top; the back vertical and the face with a batter of 2 inches to the foot, or the base is equal to 0.35 of the height. A wall of this height (20 feet), to be just equal in resistance to the pressure of the water, should be at least 8.4 feet, or 0.42 of the height. The numerous retaining-walls added at intervals of 30 feet protect it from overturning. The back-water extends half a mile; the average width is 600 feet.

The ground contiguous to the works is in the shape of a horseshoe. At the apex or top there is a basalt dike, 80 feet high, which being in the bed of the old stream, the water has eroded a deep ravine below, and caused the present topography. On one side is a watertank, to be subsequently mentioned, on the other are the works.

The Furnaces. In a deep excavation in the hillside, No. 1 furnace was built. Stack (brick), 28 feet high; bosh, 6 feet 5 inches, inclination, 50°; throat, 3 feet; hearth, 19 by 20 inches, rectangular; two tuyeres, 1 inches and 17 inches above hearth-line; cold blast; pressure, 1 pound.

The lining above the bosh is of refractory stone, said to have been in use thirteen years; the hearth is of stone. From the tuyeres to the bosh a composition is used, made of equal parts of clay, from a place called Capula, powdered stone, and powdered quartz. It gen

erally lasts from four to six months. Blast is supplied by two double-acting wooden blowing cylinders, with clock valves; diameter, 3 feet; stroke, 7 feet. These also furnish blast for four bloomary fires and two smiths' forges. This machine is driven by a 30-feet overshot water-wheel, which gives about 46 per cent. of the power of the water used. This wheel drives also a small drill-press and turning lathe.

In front of furnace No. 1 is the foundry, 40 x 60 feet, arranged with suitable cranes and apparatus. To the right, in an excavated space, are two badly constructed cupolas and the exit gate. At the end is the carpenter shop, very small and crampy, beneath which is a storeroom for pig iron and billets. On the same level is the bloomary, twenty feet below the level of the foundry, to the left, which consists of four bloomary fires, two trip-hammers, operated by separate overshot water-wheels of 15 feet diameter. In the same building are also an old single-puddling furnace and nine-inch bar mill, both now worthless and abandoned. About fifteen feet to the left of the foundry and furnaces is a reservoir, 50 x 80 feet, which catches the water from the 30-feet water-wheel and delivers it to the water-wheels of the bloomary.

Furnace No. 2 is immediately behind or to the south of No. 1 about twenty feet, in a space excavated for the purpose. The stack was of cut stone, with ornamental cornices. It was erected in 1869. Two horizontal wooden blast cylinders, 4 x 7 feet, were geared to the above-mentioned 30-feet water-wheel. A Wasseralfingen stove was constructed to supply hot blast. An attempt to blow in was made, and after two weeks' severe labor a gas explosion destroyed the stove, the machinery was found ineffective, the work was abandoned, and the lining torn out. Such was the condition of the old works in 1870, which are said to have absorbed $400,000, without taking into consideration the hacienda, church, workmen's houses, and other improvements necessary for the existence of iron works.

THE NEW WORKS.

Blast furnace No. 2 has been reconstructed after plans furnished by Messrs. Taws & Hartman, of Philadelphia. Hearth (round), 3 feet 6 inches diameter; bosh, 9 feet; height, 35 feet; throat, 3 feet; two tuyeres, 3 inches diameter and 30 feet above the hearth-line.

It is lined from the mantle to the throat with the so-called refractory stone. This is a white magnesian silicious stone, which, when