In the same way two molecules of Göthite, less one molecule of water, give one of Turgite, thus:

or graphically,

((HO),(Fe,O,)),—H,O=(HO),(Fe,Os),

HO-Fe) OH HO

Fe2-OH

This mineral, also, might be considered but for analogous com

It would appear that much confusion has been the result of attempting to classify the hydrates of iron according to the few species now generally admitted, and that the name of each, and of Limonite in particular, has been probably made to do duty for more than one thing.

Any one will appreciate how easily this might occur who knows the chemical activity of iron, and who has seen the varying shades of color and grades of lustre and density which characterize the contents of any iron ore bank.

It has been the writer's task to try to show that numerous ores of iron were possibilities, and that some were actually found by analysis but remained unnamed.

THE ROTHSCHÖNBERGER STOLLEN.

BY ROSSITER W. RAYMOND, PH.D., NEW YORK CITY.

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

THE 12th of April, 1877, witnessed the celebration, at Freiberg, Saxony, of an event profoundly important for the ancient mining industry of that district, and full of interest to mining engineers throughout the world-namely, the connection of the famous Roth

schönberger Stollen with the Freiberg mines. Since the invention and perfection of steam machinery for pumping, winding, and ventilation, the supreme importance formerly conceded to deep adits has declined. Yet such works still remain, in many cases, measures of true economy; and the instance just referred to furnishes a striking example of a vast undertaking, steadily pursued through many years, and completed, at last, just in time to afford vital relief to a declining industry, which has lasted through seven centuries.

To engineers it is also interesting, as furnishing another proof (if any were needed) of the efficiency of machinery in works of this character.

I have thought, therefore, that'a brief description of this adit, together with tabular exhibits of its progress and cost (for the material of which I am chiefly indebted to Mr. Adolf Mezger, Mining Engineer, of Freiberg), would be welcome to the members of the Insti

tute.

Already, in the last century, the difficulty of dealing with subterranean waters had caused the abandonment of some of the most important groups of mines around Freiberg. To those acquainted with the locality, I need only mention the Halsbrückner Spatgang, the Thurmhofer Zug, and the Hohebirker Zug. In the first quarter of the present century it was evident that mines at other points in the district would suffer a general decline, and certain final cessation of active operations, from the same cause. The use of steam power was deemed too costly for an industry based upon small veins, and ores mainly of low grade. A deep adit was the only other remedy; and in 1838, Oberberghauptmann von Herder published his famous plan of the great Elbe adit (der tiefe Meissner Stollen), which, starting from the Elbe at Meissen, should pursue a straight course to Halsbrücke, a distance of 22,000 meters. At that point it would drain the ancient and abandoned mines belonging to the state, and beyond that it could be continued and connected with the various deep mines of the Freiberg district, at the cost of the parties benefited. The depth of this adit, below the deepest then existing, would have been about 183 meters.

As is well known, this plan was finally abandoned, as requiring too much time and money, and, in lieu of it, the Freiberg authorities urged upon the government, in 1843, the undertaking which has recently come to a successful end. This plan, the execution of which was commenced in 1844, and has been steadily continued for nearly thirty-three years, contemplated an adit from the Triebisch valley at

Rothschönberg, about 12 kilometers above Meissen on the Elbe. The distance to Halsbrücke was to be 12,882 meters (exclusive of 334 meters of auxiliary drain); the depth below the Anna Stollen 94 meters, or 89 meters less than that proposed for the great Elbe Stollen; the height and width of the adit, 3 meters respectively, and the grade 3 millimeters to the meter. The adit was to be prosecuted from the mouth, and from seven air-shafts; the estimated time required was twenty-two years, and the estimated cost was 1,300,000 thalers, or $950,000, gold. Both the time and the money were considerably exceeded, as will be seen by reference to the details given below. The causes of this disappointment (nothing unusual, by the way, in enterprises of this character), were unexpected hindrances and difficulties of every kind. Among them may be mentioned the penetration by the first air-shaft of an ancient ravine, filled with quicksand; the encountering, in the different headings driven from the air-shafts, of unlooked for quantities of water, and a change of plan in the interest of the Halsbrücke mines, and those of the Freiberg district beyond, involving an eighth air-shaft, and an increase in the length of the government adit—the new length being (inclusive of 846.84 meters auxiliary drain) 13,900.79 meters. Moreover, the originally estimated cost was appropriated in nearly equal instalments annually; to the great delay of the work in the first few years, when the sinking of shafts, the erection of buildings, and the purchase of machinery, consumed large sums. The influx of water, above alluded to, necessitated the erection of more powerful machinery, and suspended actual progress in the meantime. Experience has shown in this instance, as in the striking instances furnished by the Sutro Tunnel and the deep mines on the Comstock lode in our own country, that it is not safe to presume on the absence, or small quantity, of subterranean waters, even at depths below those in which the mines are comparatively dry. The amount of water continually standing or circulating, at great depths in the earth's crust, is a matter concerning which little is known or speculated; but reflection will convince us that it must be very great, since nothing but absolutely impermeable and insoluble rock (if such exists), or a zone of heat too intense to permit the existence of water, as water, can form its lower limit. The effect of such an all-pervading agent in the metamorphosis of rocks, under high pressures, and at great depths, is a subject most interesting to geologists, and not yet exhausted. The possible ascription of the increasing heat encountered as we penetrate the earth, to the reaction of water upon the rocks and minerals, is

likewise a most inviting topic, upon which I shall not enter here, further than to say that whatever may be the lack of evidence for such a theory, it cannot well be urged against it that water does not exist in the deep strata in sufficient abundance to permit such action. to take place on an adequate scale. The indications of experience are rather the other way, although the greatest depths attained by human explorations are trivial in comparison with the dimensions of the earth, and can scarcely give conclusive evidence on either side.

But one of the greatest causes of delay and expense in the construction of the Rothschönberger adit was an element which I do not find set forth in the congratulatory speeches of the orators who celebrated its completion. I refer to the steady decrease in the efficiency of the workmen. Perhaps the Freiberg district is not alone in this respect; but certainly the day's work of a man has diminished there to very unsatisfactory proportions. This is due partly to the fact that as the industry declined, the younger men have sought their fortunes by emigration, until the government works have come to be almost an eleemosynary institution for the support of decayed and superannuated veterans. But this is itself an effect as well as a cause. The policy of paternal government, with its adjuncts of pensions, insurances, regulated labor, and the like, has many good features; but the danger in all such systems is the gradual loss of independence and ambition on the part of the laborer, and conversely the loss of such laborers as possess these qualities. In many foreign states, the government has planned anxiously to prolong work for the miners of certain ancient, halfexhausted districts. What more natural result than that the miners, catching the infection, should plan to prolong work for themselves, nursing every job to make it pay wages as long as possible? The interest of society is to save labor. The immediate interest of the laborer is to sell labor. And this is the root of the contest between capital and labor. No doubt the laborer often seeks his immediate interest at the sacrifice of his permanent interest, or that of his class and country. In the present case, for instance, the slow and lazy progress of the deep adit, while it prolonged the occupation of a few men, delayed the commencement of a new era of activity throughout a considerable area, which will give occupation to many men. As might be expected in such an atmosphere, the modern improvements in drilling and explosives were not adopted. Experiments were made by the skilful engineers who abound at Freiberg, and reports of value were published; but a vigorous adoption of the new labor

VOL. VI.-35

saving agents did not take place. The exodus of labor to more promising fields had left the Freiberg mines in such a condition that the discharge of a miner for mere laziness and inefficiency was regarded as a sad, last resort. To force upon the miners improved machinery and explosives, was a step too daring for the authorities, who, having coddled their laborers into insubordination, were now at their mercy. I think it was in 1875 that the unfavorable report upon the use of machine-drills in the Himmelfahrt mines was given to the world. In the same year Mr. Adolph Mezger, a mining engineer known to many members of this Institute, whose years of practice in this country, Russia, Mexico, and Greece had enabled him to perceive, and whose native energy urged him to adopt, whatever was most effective in methods and machines, took a contract to finish the Rothschönberger adit. The condition of the work in October of that year is shown by the sketch on Plate XI. Air shaft VII was fully connected with the main tunnel. Air shaft VIII was not connected, and required constant pumping. The work of connecting these two shafts was slowly progressing; and the continuation southward from shaft VIII to meet the counter-drift from the Himmelfahrt mine, a distance of about 250 meters, was the work undertaken by Mr. Mezger.*

After much annoying delay, and in the face of no little opposition, he got under way, employing Burleigh drills. Before the contract was completed, he had succeed in maintaining a regular rate of progress of 6 meters a week (3 meters high by 3 meters wide), or say 84 feet per month. This, under the circumstances, must be considered excellent work. The Sutro Tunnel header advanced in 1875 at the average rate of 94.7 meters (310.7 feet) per month, the best month's work being 112.6 meters. In 1876 the average monthly rate was 93.2 meters, and the best month's work 109.6 meters. But the rock in the Sutro Tunnel is less refractory than the Freiberg gneiss; the section of the Rothschönberger (3 meters square) is onefifth greater than that of the Sutro (8 feet by 10 feet), and the difficulty of working from an air-shaft is considerably greater than that of driving a header already connected with the tunnel mouth. Nevertheless, there remains a surplus of progress in the American work which I feel justified in ascribing to the superior efficiency of our miners and laborers. On the other hand, the cost of the work

* Among the honors distributed at the celebration, Mr. Mezger received, in recognition of his skill and energy in completing the work, the decoration of the Albrechtsorden.