is increased, and there is attached to the lower end of the suspension bars a suitable frame, which, in combination with the "carrier," is furnished with joints, enabling all necessary angles and curves to be passed. Figs. 5 and 6 show the double carrier for conveying a self-dumping bucket or car holding 500 pounds of ore. By increasing the number of

carriers, and thus distributing the load along the rope, the load or weight to be conveyed can be also increased.

The rope being set in motion, carries with it the various loads of ore or whatever material is transported; passing without impediment all the bearing and guide-pulleys, as well as the end grip-pulleys. On account of the arrangement of the bearing and guide pulleys a and b, Fig. 3, the rope cannot jump out from the groove of the pulleys under any circumstances, while they permit the rope and its load to pass over any mountain or through any valley.

The curves are passed in two ways. For a very acute angle two horizontal grooved pulleys are employed, the rope of the interior angle passing around in manner shown in plan, Fig. 7; and for ordinary curves a series of pulleys are so placed that the rope always leads fair on to the next pulley, being deflected in passing off at an angle not to exceed 11o, until the curve is completed. This manner is shown in Fig. 8. Fig. 9 shows another mode of conveying the ore. The car being on an

Fig. 9.

inclined track, is taken up by the carrier, which has attached to the lower end an inclined bar fitted with notches.

The speed of the rope is usually 200 feet per minute. If the ore-sacks contain 150 pounds, and are suspended every 50 feet, 36,000 pounds are delivered per hour, at a cost, including interest, wear and tear, &c., estimated by the patentee at from 20 to 40 cents per ton per mile.

CHAPTER XXIII.

ELECTRICITY AND ROCKS.

This chapter was read by me as a paper before the American Institute of Mining Engineers, at their Troy meeting, in November, 1871. There is much vague theorizing about the connection between electrical currents or discharges and the formation of mineral-deposits, and those who substitute the word "magnetism" for "electricity" mean probably the same thing. There is no need of being exact when one is explaining things on a grand scale, and without reference to the details, that is to say, the facts!

In a brief treatise on mineral-deposits, contained in my report of 1870 on mines and mining, I have intimated my view of the limits to which electrical theories of vein phenomena should be confined, namely, those of chemical reactions, either taking place in vapors or solutions. of mineral substances, and resulting in precipitation, or occurring in the permeable contents of mineral-deposits already once mechanically or chemically precipitated, and resulting in varied metamorphosis. In the latter case, as well as in the former, the process, strictly speaking, involves the presence of vapors or liquids, since this is a condition of all chemical reactions. The effects produced, aside from such as I have described, by the mere transmission of magnetic or electrical currents through solid rocks, I believe to be trivial and rare. Mr. Darwin, in his "Voyage of the Beagle," describes the vitrified siliceous tubes of La Plata, caused by lightning entering loose sand. In the second volume of the "Geological Transactions," referred to by the same author, there is an account of the similar formations, called fulgurites, occurring at Drigg, in Cornwall; and another case is described by Ribbentrop, in Germany. I quote a part of Darwin's description:

"Four sets entered the sand perpendicularly; by working with my hands I traced one of them two feet deep; and some fragments, which evidently had belonged to the same tube, when added to the other part, measured five feet three inches. The diameter of the whole tube was nearly equal, and therefore we must suppose that originally it extended to a much greater depth. These dimensions are, however, small, compared to those of the tubes from Drigg, one of which was traced to a depth of not less than thirty feet.

"The internal surface is completely vitrified, glossy, and smooth. A small fragment exhibited under the microscope appeared, from the number of minute entangled air, or perhaps steam-bubbles, like an assay fused before the blow-pipe. The sand is entirely, or in greater part, siliceous; but some points are of a black color, and from their glossy surface possess a metallic luster. The thickness of the wall of the tube varies from a thirtieth to a twentieth of an inch, and occasionally even equals a tenth. On the outside the grains of sand are rounded, and have a slightly glazed appearance. I could not distinguish any signs of crystallization. In a similar manner to that described in the Geological Transactions, the tubes are generally compressed, and have deep longitudinal furrows, so as closely to resemble a shriveled vegetable stalk, or the bark of the elm or cork tree. Their circumference is about two inches, but in some fragments, which are cylindrical and

without any furrows, it is as much as four inches. The compression from the surrounding loose sand, acting while the tube was still softened, has evidently caused the creases or furrows. Judging from the uncompressed fragments, the measure or bore of the lightning (if such a term may be used) must have been about one inch and a quarter. At Paris, M. Hachet and M. Beudant succeeded in making tubes, in most respects similar to these fulgurites, by passing very strong shocks of galvanism through finely-powdered glass; when salt was added, so as to increase its fusibility, the tubes were larger in every dimension. They failed both with powdered feldspar and quartz. One tube, formed with powdered glass, was very nearly an inch long, namely, 0.982, and had an internal diameter of 0.919 of an inch. When we hear that the strongest battery in Paris was used, and that its power on a substance of such easy fusibility as glass was to form tubes so diminutive, we must feel greatly astonished at the force of a shock of lightning, which, striking the sand in several places, has formed cylinders, in one instance at least, thirty feet long, and having an internal bore, when not compressed, of full an inch and a half; and this in a material so extraordinarily refractory as quartz!"

It is unnecessary to dwell upon the power of electricity thus manifested. It is manifested to us in several instances where houses are struck by lightning, and metallic objects are instantly melted by the surcharging current. What I wish to point out is the comparative rarity of such electrical effects in nature, and particularly in ore-deposits. We do not find in these, as a general rule, any traces of vitrifying fusion, and we may fairly conclude that they are not particularly liable to this form of electrical action. It has, however, occurred to me that some puzzling cases in mineralogy might be due to this cause. Every mineralogist now and then encounters specimens sincerely alleged to be Lative, i. e., in a natural state, but which he recognizes as the products of more or less perfect fusion. In most instances, no doubt, the fusion has been artificial, and the specimens are really forge or furnace produos. Sometimes, however, they may be really native, and vitrified by lighming. Mr. Daubré, in a paper on meteorites in the Annales des Ming for 1868, remarks that lightning produces on the rocks of the eartha varnish which is not without analogy to that of meteorites. It occasins, namely, on certain rocks, particularly toward the summit of mountains, the formation of little drops, or of a glaze, to which De Saussub first called attention. It was on account of this resemblance that the avants to whom certain meteorites were submitted, which fell at Lucè in 1768, expressed their opinion that they were merely terrestrial stones vitified by lightning.

But the rarity and comparatively insignificant extent of such phenomena, and the fact that nothing of the kind is observed as normal to mineral-depoits, even at their outcrops, warrants me in saying that electrical distarges of this character cannot be considered as active agents in the ormation, filling, or metamorphosis of veins.

I pass to consder another class of electrical phenomena, namely, those connected with he electric resonance or boudonnement of mountains. Mr. George S. wight, of Montclair, New Jersey, has communicated to me a recent cas of this kind, personally observed by him on Gray's Peak, in Colorado, he highest summit of the Rocky Mountains. He ascended this peak ith a party about the 10th of June last, reaching the top at 2 p. m. "ouds had been gathering for an hour or two, and storms were in prosess on the adjoining ranges, principally to the north and east, with avy, rumbling thunder at brief intervals. "A

strong wind from the west," says Mr. Dwight, "drove us to shelter behind a pile of stones some four feet high, which former visitors had erected as a screen. Behind this we crouched for some time, resting and viewing the gorges below. Presently one of the party arose to a standing position, and the instant his head and shoulders were elevated above the protecting line of wall, a hissing sound was heard by all of us. Our friend, with a possible suspicion of snakes, turned about in a bewildered manner to ascertain whence the noise came, and in a moment exclaimed, 'Why, it is me!' His hair stood out, and the gold spectacles he wore, about which there was doubtless some small amount of steel, crackled. At first we were disposed to laugh heartily at his experience, but, as one by one we rose, (there were four of us,) and encountered the same phenomena, we thought best to beat a hasty retreat from a spot which might prove dangerous, and discuss the theory on a lower plane. Each of us experienced the sensation the moment we entered the draught or current from the west. The sound was as loud as that produced by the effervescence of ale from a partially uncorked bottle, and similar in character, though a trifle more whistling in tone. It was accompanied by a strong smell, as of sulphuric or muriatic acid fumes. We all felt the prickling sensation in our fingers also, and a certain exhilaration. These passed away as we descended, and I should say left us entirely within 250 feet of the summit.”

Similar experiences are described by M. Fournet, in the Comptes Rendus de l'Académie des Sciences of 1867, and also by M. Henri de Saussure, in an article translated for the Smithsonian Report of 1868. The cases enumerated are seven in number, and the circumstances strongly resemble those above related, except that the odor perceived by Mr. Dwight and his companions, possibly due to the presence of ozone, is not mentioned in any of them, though, in a number of these instances, the electric tension appears to have been very great, and, ir almost all, there was a crackling of the soil and rocks themselves, and a peculiar vibration of the staffs or alpenstocks of the last observers, called the chant des bâtons. Invariably, according to the authorities quoted, there was an attendant shower of hail or sleet at the summit of the mountain. M. Fournet mentions also an instance of nocturnal luminosity on the Grands Mulets (Mont Blanc) as referable to a sinilar electrical condition.

De Saussure draws from the observations discussed by him tie following conclusions:

1. The efflux of electricity from the culminant rocks of moutains is produced under a clouded sky, charged with low clouds, envelping the summits, or passing at a small distance above them, but whout the occurrence of electric discharges above the place whence the continuous efflux is proceeding. It would seem, therefore, that when this efflux takes place, it sufficiently relieves the electric tensio to prevent lightning from being formed.

2. The continuous efflux of electricity from the groud toward the clouds is not unconnected with the formation of vapor and probably also with that of the hail.

These electrical phenomena seem not to be rare high regions, though they are by no means frequent. Many persos accustomed to climb mountains, such as guides and hunters, have ever observed the electric resonance; others have heard it but one or twice in their lives. But, as De Saussure acutely remarks, it isprecisely on those days when menacing skies repel adventurers from ae highest altitudes that the phenomenon manifests itself.

If we now inquire what are the permanent physical traces left by this electric tension or efflux, we find nothing at all. Gray's Peak is a locality within my personal acquaintance, and it bears the marks of far other agencies than this. The whole mountain, for some hundreds of feet below the summit, appears to be a heap of broken fragments, sometimes erroneously called boulders. These have undoubtedly been produced from the exposed crags and ledges, and chiefly through the agency of frost. There is good reason to believe that this and many other summits have been frozen through, and that the summer thaws do not penetrate into their solid portions, except so far as disintegration may be still advancing year by year. I have been informed that the tunnel of the Baker mine, which is above timber-line on the Kelso Mountain, adjoining Gray's Peak, did not, by penetrating 200 feet, get beyond frozen ground. But neither the Baker mine nor the Stevens mine, which is about at an equal altitude on the McClellan Mountain opposite, nor any other of the numerous mines in our western districts, situated at great elevations, presents, so far as my observation goes, peculiar appearances referable to electricity as the cause.

In reply, then, to the assertion of electric theories of vein-formation, it may be said that they lack the basis of direct proof, and that the indirect evidence of analogy is against them. We are acquainted with certain effects of electricity upon rocks; these effects we do not find in ore-deposits; and what we do find there is referable to other causes. The prudent theorist will be content, for the present, with electrochemical, not electro-physical, action, and confine himself to the study, in this department, of the possible existence and effects of galvanic currents in vein-contents, depending upon chemical reactions.