which the bit is detached from the rods when they are lifted to the height necessary for the proper fall; it then drops by its own weight, whilst the rods follow separately, and when they have been again lowered to the neck of the tool an opposite action to that which detached it causes it to be caught and held firmly while it is being again raised to the requisite height.

The value of these improvements to the practical borer becomes apparent on considering the results obtained.

With regard to the use of light wooden rods, we may notice the sinking of a hole at Besch, in Luxembourg, to the depth of 290 yards, at a cost of £320. As an example of the use of wooden rods and the free fall tool, the deep sinking at Mondorff, in Westphalia, may be quoted. The first 371 yards had cost £1,873, and occupied 37 months; this gives an average cost of £5 1s. per yard. This depth was bored by the ordinary methods. M. Kind then introduced his improvements, and succeeded in sinking the remaining portion, 393 yards, in 14 months, at a cost of £829, or £2 2s. per yard.

The tool employed in M. Kind's system weighs from 8 to 10 cwts., and makes from 8 to 25 blows per minute, according as manual power or that of machinery be made use of; the fall is usually about 2 feet, but varies from 1 to 3 feet, and the usual size of the hole is 12 inches in diameter. The rods are 45 feet long and connected by male and female screws.

The average cost of boring by various systems for holes of from 250 to 400 yards in depth, where no extraordinary accidents have happened, may be thus given :

The cost of the well at Grenelle amounted to £14,500, or £24 per yard.

We now come to the third improvement of M. Kind, viz: that of obtaining cores. This is effected by means of two distinct tools. The first is a crown borer, consisting of five different chisels: this tool works by percussion and makes a circular cut, this arrangement is subsequently replaced by another of a circular form, with curved teeth pressed inwards by a spring; this is passed down on the core, and when at the bottom of the cut made by the first tool, a slightly rotary motion is imparted to it;-the teeth in this way are made to form a groove around the core; a jerk is then given to the whole, when the core becomes detached, and is brought to the surface, taking care not to

twist the rods in bringing them up. The precise strike and dip of the strata may in this way be ascertained. In this manner cores of the length of two feet have been obtained, and by thus knowing the exact dip of every bed passed through, its true thickness is determined.

M. Kind has likewise attempted borings of a size sufficient for ordinary shafts, and in this respect has also been successful. A shaft 14 feet in diameter was bored 100 yards in 9 months; another small one 4 feet in diameter was carried to a depth of 120 yards in 7 months, at a cost £1 4s. per yard.

The application of boring to sinking shafts in collieries where water is an impediment, or in metallic mines to making connections with lower depths which are in communication with means for unwatering, is an important consideration, and it is to be regretted that in this country we have not given that attention to the subject which it deserves.

The field open in this direction is wide and important, and cannot fail largely to reward, in a pecuniary sense, any intelligence which may be devoted to its development.

MINING AS AN INVESTMENT.

THE mineral resources of Great Britain are, at the present time, being developed with unexampled rapidity, and every year adds considerably to the number of mines in active operation.

It was formerly customary to carry on mining undertakings chiefly by means of local capital; but, of late years, associations have been formed for that purpose, both in London and many of the larger provincial towns. These associations have greatly stimulated mining industry, and, although not managed perhaps as cheaply and advantageously as some of the smaller adventures, yet they have unquestionably conferred important benefits on the miner, and given considerable impetus to commerce.

The mines best known in the market are chiefly those of copper, lead, and tin, in addition to which a few quarries and collieries also claim a portion of public attention. The former are mostly situated in Cornwall, Devonshire, Wales, and the North of England; the latter in Wales and the Northern counties. A marked distinction is, however, to be made between metalliferous deposits, slate veins, and coal seams. The value of the one class of property is invested with much uncertainty, whilst that of the other may in most instances be ascertained with a greater degree of accuracy.

The metallic ores are usually found in lodes or veins following a given direction, and intersecting the strata at greater or less angles. In some cases, however, such deposits are interfoliated between the lamina of the beds constituting the strata.

A lode intersecting the cleavage of the strata is generally spoken of as a true vein. It may be of indefinite length and depth, and has commonly a greater or less inclination with the meridian. Its composition is usually different from that of the enclosing rock. The distance between its two walls is called the width or thickness of a vein, and may vary considerably. In Europe a metalliferous vein is considered wide if it exceeds five or six feet in thickness. The deposits of ore occurring in veins are extremely irregular, forming masses of very diversified form and extent, separated from

each other by intervening patches of veinstone, which may be either entirely devoid of mineral, or otherwise mixed with inconsiderable quantities of finely divided ore.

In mountainous districts veins are often explored and worked by means of galleries driven from adjacent valleys. In this way the ground is unwatered, and a direct communication established between the different workings in the mine. When the conformation of the country will not admit of a deep gallery of this kind, the explorations are carried on by means of shafts drained by machinery. This is effected by sinking one or more main shafts, and fixing pump-work to remove such water as may be met with during the progress of the operations. Galleries right and left of the shafts are then extended at vertical intervals of about 10 fathoms, and any ore existing between the various levels subsequently stoped out, whilst the sinking of the shaft is continued in proportion as the workings advance.

The uncertain nature of metalliferous mining affords unusual facilities for making unscrupulous misrepresentations, and consequently whenever, through the abundance of money or other favourable causes, the public mind becomes credulous, it admits the grossest misstatements without examination, and readily consents to pay exorbitant sums for properties which are, probably, altogether worthless, or at least of but little intrinsic value. Sooner or later, however, the truth is arrived at, and, under the influence of a violent reaction, an industry that deserves well is denounced as a delusion, whilst the real circumstances producing the evil are either slurred over or forgotten.

It is often asked if mining, on the whole, is a profitable industry. It may be replied that it is not only profitable but largely so, provided caution and judgment be exercised in selecting the mines, and due integrity, skill and economy, displayed in their management. If, however, these conditions be not fulfilled, the most disastrous consequences may be anticipated; since worthless undertakings will in this case be supported by the public, and after subscribers have paid extravagant premiums for indifferent properties, the capital necessary to develope them will either be squandered or injudiciously spent.

It would be, perhaps, difficult to conduct mining operations to any considerable extent without such a division of interest and contribution of means as to diminish, in a great degree, the pressure which must be individually felt where the number of shareholders is small. It is, however, questionable whether it be prudent to extend the number of shares beyond a reasonable limit; since it is evident that reduction of price must tend to create an undue traffic in them, and their value is consequently made to

fluctuate rather in accordance with a more or less unhealthy state` of public feeling, than with reference to the intrinsic merits of the undertaking itself.

Mining operations are conducted either on the cost book system, under the Joint Stock Act, or the recent Act for limiting the liability of shareholders. The cost book system has, when fully carried out, many excellent features; since it not only provides for the immediate relinquishment of shares, but also completely limits the liability of subscribers. This system had probably its origin in local customs; but its true principles have, unfortunately, been seriously perverted by attempts to render them conformable with the practices governing ordinary commercial enterprises. The routine of mining is peculiar to itself, and its operations are of such a technical character as to necessitate a considerable departure from the general usages of trade. A mine may be intrinsically good, but unless it be worked so as to anticipate a great variety of contingencies, not only the interest of the adventurers must be prejudiced, but the character of the neighbourhood as a mining district may also be seriously affected. Although it is desirable to limit the liability of individual shareholders, it is nevertheless somewhat hazardous to apply this principle of limitation to all the uncertainties and vicissitudes attending mining explorations, unless a wide and ample margin be preserved over and above a reasonable estimate of the necessary expenditure. No individual, on entering upon experimental mining, should exceed to a large extent his surplus means, or in any case risk a greater sum than he would be enabled to lose, without injury to his credit, should the speculation prove unfortunate.

Mining may be classed under two distinct heads, viz.: experimental and profitable. The first comprehends the various researches necessary to establish the presence of metallic ores in remunerative quantities; whilst the second, or profitable mining, includes all properly developed undertakings in which a sufficient amount of ore has been discovered to ensure their being advantageously worked for a more or less extended period.

A capitalist wishing to become associated with a company prosecuting a mining enterprise should first inquire into the character of the district in which the mine is situated; secondly, the honesty and ability of the person reporting on it; and, thirdly, ascertain if the shareholders generally are in a position to meet the demands which a vigorous trial would be likely to impose on them. The constitution of the undertaking should also be investigated. Free shares are generally objectionable, and the system of giving a large sum of money for an untried property is highly pernicious; since, in addition to its effects upon the ultimate profits