Cornish poll pick for hard ground: Length over eye, 2.2inches; of poll-end, 3 inches; of pick-end, 12.5 inches; thickness (depth) at poll-end, 1.2 inch; at pick-end, 1.1 inch; width over eye, 3.1 inches; at poll-end, 1.2 inch; at pick-end, 1.1 inch; poll-end 8-sided; point set at 850 to handle.

Cornish poll-pick for soft ground: Length over eye, 2.1 inches; of poll-end, 3 inches of pick-end, 17.5 inches; thickness at poll-end, 0.8 inch; at pickend, 0.9 inch; width over eye, 1 inch; at poll-end, 0.8 inch; at pick-end, 0.8 inch; point set at 83° to handle.

Derbyshire double pick, used in rock or vein, with short points.

Derbyshire "slitter," double, one side pointed, the other horizontal edge, 0.4 inch wide.

Derbyshire poll-pick, (mandrel,) short, bluff point; for hard veins and rock, where slitter" is too slight.

Northumberland, double, straight-armed; arms thickened in the middle, like two gads.

Flintshire, single-pointed, with short 8-sided poll.

Flintshire, double; one wedge-point arm, the other with horizontal, chisel edge, 0.1 inch wide.

Monmouthshire (coal) cutting mandrels; straight, taper directly from center to points.

Monmouthshire holing mandrel, stronger and bluffer.

Monmouthshire bottom mandrel; curved, double-pointed.

Monmouthshire bottom mandrel; curved, 2 chisel arms-1 horizontal, 1 vertical.

Monmonthshire rock mandrel; curved, 8-sided arms-1 wedge-pointed, 1
chisel end.

Flintshire (coal) metal-driving pick; tapered V cheek-pieces.
Flintshire (coal) holing pick; tapered V check-pieces; chisel-edged arms,
0.1 inch wide, with strongly curved top surface.

Flintshire (coal) heading pick; tapered V cheek-pieces; slightly curved;
arms taper regularly.

North of England, (coal;) lower edge horizontal; top, 2 inclined planes; in plan, a lozenge, diminishing from center.

North of England; like the foregoing, except that the arms are bent or
anchored, inceting at 1555.

North of England stone pick; slightly anchored; tapering V cheek-pieces;
arms beveled to 8-sided sections, with 4-sided pyramid at points.
North of England stone pick; like the foregoing, but stronger and more
anchored.

Saxon pick; single armed; tapered octagonal section; no poll; greatest
thickness, 1.5 inch; breadth over eye, 2.12 inches; head set at 85° to
handle.

Russian poll-pick; slender curved arm; length of pick-end, 12.8 inches; greatest diameter, 0.7 inch; eye circular.

Russian gravel pick; single curved arm; blade broadens to a spoonbill near the point.

It is curious to notice how great are the variations in this apparently trivial tool among different nations. Yet the proper form of a pick is not unimportant. If it only affected by a small fraction (and it does more than that) the amount of work which a laborer can perform daily, its aggregate importance to the effective daily labor of the world could scarcely be estimated in money. Our American patterns are so excellent, that there is little excuse for those who do not select the tool best suited to the work.

The Saxon gad resembles a long slender hammer. It is furnished with a narrow rectangular eye. When in use, it is held by a handle inserted into this eye, and is driven by striking the poll-end. A common size is, length of the iron, 6.2; of the eye, 0.86; of the handle, 14.0; breadth across the eye, 0.95; greatest depth, 0.7-all in inches. The point is formed by a small bluff pyramid, and the poll-end also contracts suddenly. Weight, 10 ounces. As the Saxon miners are enabled, from the fissured character of the rock, to make considerable use of these gads, they carry them under-ground in sets of a dozen or fifteen, strung

by the eyes upon iron stays, with a joint or yoke in the middle, so that the whole may be slung over the shoulder, the gads being equally distributed before and behind. The gad passes over, as it were, by degrees into the pick. Thus the fimmel is a large hammer-like gad, weighing, with handle, 2 pounds, 8 ounces, and having a head 10.2 inches and a handle 12.6 inches long. The small heavy poll-pick, weighing 7 pounds, 12 ounces, is very similar in form, but has a head 13.5 inches, and a handle 19 inches long. The ordinary German gads, and those of Hungary, are stronger and more hammer-like than those of Saxony. The Hungarian steel gads weigh 13 or 14 ounces, and the common gad 2 pounds 6 ounces.

HAND-DRILLS.

The hand-drills in California are made of English octagon steel, generally one inch in diameter for ordinary powder; sometimes, but rarely, 14 inch; and the striking hammers weigh from 8 to 10 pounds. For the new "giant powder" a three-quarter-inch drill is used, and the striking hammers weigh from 3 to 5 pounds. The use of proper copper-tipped tamping bars is rare, but safety-fuse is universally employed, so that the risk in using iron bars is somewhat diminished but is by no means removed.

The following pertinent observations upon blasting and hand-drilling are from notes of a lecture by Mr. Warrington Smyth, of the Royal School of Mines, England:

The introduction of gunpowder has been an immense boon to mining undertakings. It not only enables the miners towork upon rocks of great hardness at an economical rate, but it has led to the enlargement of such excavations as drifts and levels, and so placed the workmen in a better position as to ventilation, comfort, and health. Formerly the miners, when cutting the rock, were compelled, by the narrowness of the levels and smallness of the working places, to inhale the dust made by themselves in piercing the rock, and their lives were shortened in a frightful degree. The mines, since the use of gunpowder, have had to be arranged with greater regard for ventilation, and the cylindrical holes for the gunpowder are now often, while being bored, kept full of water, and the old injury to the breathing faculties are for the most part avoided. There are, of course, occasions and places where gunpowder could not or ought not to be used. Where, for instauce, fire-damp is common, and it is necessary to use safety-lamps, the lighting of a fuse with an open match will be most dangerous. In many collieries a certain man is employed to fire the shots, whose duty is to test the places beforehand. and see that no gases are present in quantities sufficient to take fire; but, as we all know, accidents do occur very often, and it is much to be desired that the practice should be greatly restricted, if not done away with altogether. Another case in which gunpowder should not be used is where the seam is much fractured and fissured naturally, so that a shot would result in so large a proportion of small coal as to make the working unremunerative. Again, its use is inadmissible in quarrying marble, or other stone, where it is an object to obtain the rock in large and perfect masses. The methods of employing gunpowder are, to a great extent, the same in principle in all the mining districts of the world. At first in this country, as elsewhere, boring the holes proved a slow and imperfect work, but, nevertheless, it soon came to be observed that by cutting away underneath, and then blowing the rock or seam down by gunpowder, one man could do as much as six with a hammer and gad alone. This, then, at starting renders it possible for a mine to be taken up and worked to profit which could not formerly have been done. The hole is bored, the powder placed in it, either loose or in a cartridge, it is then filled up, or "tamped," to the surface, and a fuse having been arranged, it is fired, and the result is that a portion of the rock is blown down. The hole is bored with what is called in different places a "jumper," a "drill," (Fr. pistolet,) or an "auger"-a piece of iron with a sharp steel ending called "a bit," which may be shaped in various forms, and then struck in the hole with considerable force and dexterity by the workman, until gradually a sufficient depth is pounded out. In most cases it is struck with a hammer wielded by the borer single-handed, but sometimes one man holds the jumper, and turns it after every stroke, while two men strike alternate blows, and thus greatly accelerate the work. The larger augers are usually from one and one-half inch to two and one-half inches in diameter, and in Germany it has been proved by experiment smaller bits are not advisable. The material of which

these borers are made has been a question of great importance. About eighteen years ago, the bar of the auger was almost always made of the best fibrous iron, the head being of steel, and the bit or edge of the best shear steel. In Derbyshire, however, they were accustomed to use cast steel, which in the fluor-spars usual there, of very moderate hardness, did very well, and lasted so long that borers bequeathed their angers to their sons; a very different state of things from that of other districts where an auger often would be worn out in a day. Cast steel, however, has been substituted generally for iron; and that because it is not only more economical, but the blow given on the head of an auger of cast steel is transmitted so much quicker to the edge as to give it a decided advantage over iron augers with steel bits. It had long been observed that when the borers had worked for some time with the iron augers some change in the metal was produced, and the blow became more effective than at first. Since 1852 steel augers have, however, become general, in spite of their greater first cost. In a case in North Wales, where very accurate accounts were kept, it was found that the use of steel borers decreased the cost of working nearly ten per cent. The form of the cutting edge varies a good deal. When the ground is moderately soft, the ordinary chisel-shaped edge prevails. In the Hartz it is often curvilinear. In Italy the borers have two edges at right angles, while in Mexico they are swallow-tailed. In all cases, however, the borer must be turned after every blow through a small portion of the circle, so that the edge never falls upon exactly the same place. When the bottom of the hole is clogged with the debris produced by the cutter, the hole is filled with water, which washes out a good deal, and a scraper takes out what is left.

There are many circumstances under which it is necessary to put down holes of a larger character; and then the augers are made larger and longer, and the hammers to strike it heavier. Stages are erected in such instances, so that on each stage several men may be placed to raise the auger, and thus a dozen men may at a word of command all lift and let go together. A jumper of this kind may weigh from two to three hundred-weight. In cases of this kind the spring pole may be used to advantage. This brings us to the question whether or not machinery may be employed for the purpose of boring, and whether it cannot be done at a less expenditure of human labor, and more rapidly.

Among the mining tools that attracted some attention at the Paris Exposition, was an apparatus for enlarging the holes in rock made by an ordinary drill, the object being to secure an enlarged space or chainber at the bottom of the hole for the reception of the powder. The apparatus is described in full detail in the Exposition Reports; but as it does not appear to be of any practical value, it is not repeated here. It is, however, well to mention that, in 1864, a miner from Humboldt County, Nevada, made a drill for the same purpose and in a similar manner. It was known as Linscott's Patent Chamber Drill, and was made, and tested upon granite blocks, at San Francisco. It consisted of a bar of steel or iron, about two and a half feet long, with movable cutters, or steel blades, about two inches long, fitted into recesses, one on each side. These, when passed to the bottom of the hole, would fly out and cut upon the sides of the hole when the drill-bar was struck upon the top with a sledge. In this way, a chamber some three inches in diameter could be made at the bottom of an ordinary one or two inch hole.

The various forms of apparatus for drilling by steam-power or compressed air are described in another chapter.

CHAPTER LXVI.

EXPLOSIVES.

"Nothing is more surprising, considering how early gunpowder was invented and used for the purpose of piercing and shattering the bodies of men, that so great a length of time should have elapsed before its application to the purpose of blasting rocks in mining. The discovery of gunpower for warlike purposes took place in 1354, but it was not introduced into mining until the last century. In a curious old book, published in 1700, entitled 'Familiar Discourse Concerning the Miné

Adventure,' which, among other things, compares the use of gunpowder as a newly introduced system of blasting with the old method of wedg ing down the material in mines, its use for mining purposes is sup posed to have been first proposed at Freiberg, by Martin Weigal, in 1613, but the idea met with little countenance, and it was not till 1631 that it began to be generally employed throughout Saxony, the Hartz, and North Germany. The practice was first adopted in Englend in 1670, at the Ecton Mines, in North Staffordshire, but the blasting at that time was but a clumsy process, and was used to blow in pieces masses of rock which had already been freed from their beds by other agencies. We must not, however, be led astray by statements in books respecting the earlier use of gunpowder in mines, as the older references to firing' belong to the still more ancient practice of 'fire-setting,' which dates from a very early period, and was, no doubt, employed by the Romans.” Even so late as the year 1862, gunpowder had not been introduced in mining in Japan, and it was introduced there for the first time by Mr. Pumpelly and the writer, acting in the capacity of mining engineers to the Japanese government. Up to that time the miners of Nipon and Yesso had cut their way through the rocks by means of the pick and gad, aided sometimes by fire, and they were very greatly astonished when they saw the hard rock at the end of a drift, abandoned by them because it was too hard to cut, thrown down by means of a few ounces of powder.

The consumption of powder for mining purposes upon the Pacifie Coast and in our mining Territories has always been large. A part of this is of course used in the construction of roads and grading for railways, but of late the consumption for breaking up the hard cemented conglomerates of the deep placer deposits has greatly increased. For this purpose very heavy charges are employed. Tunnels are driven inwards for 40 to 70 feet from the face of the bank, and cross-tunnels run for 100 feet each way, so that the excavation has the form of the letter T. A charge of from 100 to 500 kegs of powder is placed in the crosstunnel, and the whole is simultaneously ignited by electricity. The effect is to lift the whole deposit, and to shatter and loosen it to such a degree that the rest of the disintegration is readily effected by water.

Two companies, with adequate capital, are organized for the manufaeture of powder in California. The demand for powder for those regions which usually draw their supply from California, is reported to con siderably exceed 200,000 kegs annually.

The works of the California Powder Company are the only ones now in operation. At the mills of this company, situated at Santa Cruz, there were manufactured as stated in the following table:

*

From notes of a lecture by Mr. Warrington Smyth, at the Royal School of Mines, London Mining Journal, January, 1870.

Besides the above there has been some powder made at the Marin Mills, probably not exceeding 30,000 kegs of blasting powder, in the years 1867 and 1868. With the facilities now possessed by the California Company, they can turn out 640 kegs of powder daily. The kegs contain 25 pounds each.

The materials for making powder are abundant and accessible in California, with the exception of niter, which is to a great extent replaced by nitrate of soda from Peru. The peculiar dryness of the air in California for the greater part of the year permits this more deliquescenc salt to be successfully used; and, with proper precautions in the manufacture, it makes excellent powder. The capacity of the two mills is over 1,000 kegs of powder daily. A recent modification of the manufacture promises important results. Glycerine is added to the grains in some way not yet made known, and it is said to greatly increase the strength.

Works for the manufacture of safety-fuse have recently been erected in San Francisco, so that the miners can now obtain an article superior to that which is imported.

Notwithstanding the familiarity which all who use powder must gain with the many causes of accident, it is extraordinary that there should continue to be so much carelessness and recklessness in its use. One of the British mining inspectors says that in blasting an iron instead of a wooden or copper rammer is still too often used in getting the wadding and first part of the stemming fairly bedded upon the powder, and shots which have missed fire are still drawn, although experience shows that, even with water in the hole, the drill goes in advance and fires the powder. Accidents are also frequently caused by driving the pricker down into the powder.

The mineral statistics of Victoria, Australia, give exact returns of the quantities of gunpowder issued at each of the mining districts where there are magazines. In the year 1867 the quantity in stock, at the commencement of the year, in all the districts was 71 tons 16 hundredweight; the quantity issued during the year, 196 tons 13 hundredweight; the quantity received during the year, 186 tons 12 hundredweight; and the quantity in stock at the end of the year, 61 tons 15 hundred-weight. In many parts of the colony, however, there are no magazines, and great quantities of blasting powder are used there, of which there is no accurate return.

NEW EXPLOSIVE COMPOUNDS.

In introducing the subject of the new explosive compounds, which are now attracting much attention from engineers and miners, I cannot do better than to cite from the authority mentioned at the commencement of this chapter:

Of all explosives used for blasting powder is the most largely used, and continues to be the most popular. It has been, however, proposed, and that many years ago, to mingle with it various substances, and it has been tolerably well made out on the Continent that the effects of powder have not been deteriorated by a moderate proportion of sawdust being mingled with it. Within comparatively a very few years propositions have been made to completely change our explosive agents-as, for instance, by guncotton, which seemed to be peculiarly adapted for blasting purposes. It is difficult to enter upon the comparative merits of different classes of explosives on account of the great jealousies which are indulged in respecting them. This is the case even with powder, every separate manufacture of which has its advocates. Gun-cotton has, however, been most successfully employed in many places, among which may be mentioned the important quarries of the Austrian government up the Danube. In England an improvement in its manufacture was made some time ago, by which it is produced in the