In further considering the effect of wearing, it will be found that the one roller becomes dislocated a little from its central position to the one side, while the other turns into the opposite

side. The consequence thereof is, that the rollers in the course of time exhibit a kind of brims on opposite ends. Against this action a very efficient and simple construction has been proposed in Germany, by employing a guiding roller and a guided one (fig. 3). The

former gets on both ends a kind of brim or flat ring, of about 1 inch in thickness and height, while the guided one remains without this addition, but fitting itself nearly exactly between both these rings. Several years' experience have given sufficient guarantee to recommend this construction of rollers.

Fig. 3.

The laying down of Crushing Rollers.-Observing the violent blows and shocks to which a whole set of machinery is exposed in crushing-mills, where the relative places and situations of the rollers are regulated and strengthened so as

to effect by powerful lever arms and by weight hanging thereat, I endeavoured to remedy those evils. The first suggestion of employing powerful spiral springs have got no trial, because the proposition of laying the rollers upon inclined planes appeared more simple and sure. In this case the weight of the rollers performs a very useful and twofold purpose. Firstly, the weight assists the breaking of the stuff; and secondly, it makes the rollers slide down the incline on account of their gravity, after having been driven upwards the same length of the incline. Fig. 2 will readily explain the arrangements and provisions to be made :-c are the brasses in which the rollers move; b are pieces of iron to fill up all empty spaces on the one or other side of the rollers which require to stand tolerably firm in the frames; the two iron-pieces (aa) on each side of each roller have in their centres excavations, into which pieces of India-rubber are so fitted that they project at least one half-inch, while they are as much in the countersink. It has been found that this kind of buffers makes the motion of the rollers still more smooth, and adds to pressure and power of resistance.

In reference to the angle under which the rollers should be laid down, it is clear that it ought not be above, but rather under, 45°, in order that the sliding of the rollers to and fro be gentle enough, and not with too great stress. Trials to this effect have shown an angle of from 38° to 40° to answer best.

Description of a Cylinder Engine Blowpipe and Regulator. By Mr ALEXANDER KIRKWOOD, Jun., Die, Stamp, and Metal Seal Cutter, and Medallist, Edinburgh.*

The blowpipe worked by the mouth being very tiresome when used for any length of time, and also ineffective for many purposes, the idea suggested itself (when pressed for time to execute a large order) of converting a small oscillating steamengine which I had into a force-pump, acting both by up and

* Read before the Society, and apparatus exhibited, 23d April 1860. VOL. V. 2 I

down stroke, thereby giving a continuous blast, with the boiler for a condenser, to equalise the pressure and supply, and bringing the air and gas through the ordinary nozzle, a steady flame would be produced. But to render it serviceable, a regulator was required to vary the flame, which would shut off both air and gas in equal proportions, as it would be troublesome first to adjust the air, then the gas.

The regulator which I now exhibit to the Society effects this, the construction being as follows:-At the under part (fig. 1) are the ends of four tubes, one pair of which is in

tended for the entrance and exit of the gas, the other pair for the transmission of the air from the condenser of the blowpipe through the regulator to the centre of the nozzle. The four tubes are placed at equal distances from one another, and from the centre of the regulator, as represented in fig. 1. Above the two tubes through which the air

and gas escape to the nozzle-being those which are marked "air out" and " gas out"-is a flat brass disk with two arms

CAS

(fig. 2), completely closing these tubes when the apparatus is not in action. This disk (F) is shown in fig. 2 as unshaded; whilst the shaded portions, marked "air" and "gas," represent the canals in the regulator, through which the relative gases pass from the entrance to the exit tubes. In fig. 3 all the working portions of the regulator are shown, with the two entrance tubes opening into the canals or passages, and the disk slightly turned round, so as to open a small portion of both

Fig. 2.

of the exit pipes for the passage of air and gas during the working of the blowpipe. The principal object attained by the regulator is the complete control which is possessed by the operator on the size of the flame, by the simultaneous opening or shutting of equal portions of the exit tubes. The blowpipe nozzle (fig. 4), through which the gases are transmitted and burned, consists of a tube I for the passage of the gas, in the centre of which is soldered a narrower tube, con

Fig. 3.

F

veying the air; and thus, by supplying air within the flame as

an auxiliary to the air without, the blowpipe flame is obtained in perfection.

On Some of the Derangements of the Scotch Coal-field. By Mr JOHN J. LANDALE, M.E.*

The miner, in his explorations, is favoured with occasional glimpses of some of the most wonderful and interesting geological phenomena, and in many cases is enabled to trace with no small degree of accuracy some of the changes and revolutions which the strata of our globe have undergone. His operations pierce through deposits which have been laid down regularly and systematically age after age-deposits which speak of other organisms than those with which we are now acquainted, and which tell of the duration and extent of sea and land ages before man was introduced on the scene.

* Read before the Society, and drawings exhibited, 23d April 1860.

He opens a book of many pages, every leaf teeming with symmetry and beauty, and every chapter a wondrous chronicle of life and death, an unerring record of the past. Many of its leaves are frayed and torn, and often we want a key; but still we may read of the many glorious wonders wrought in these long ages of still silence of a power which has had no limit, a volition which was never exercised without foresight, and of a method and purpose which, even when inscrutable to us, the highest of His creatures, exists in and pervades the great work.

The subject of this paper is one of considerable interest, and one on which few geologists have bestowed more than a passing notice (principally, I fancy, because their observations have been limited, or chiefly so, to investigations at the surface), and one on which the working of mines can alone give us proper and reliable information.

In the course of the following remarks, I shall only advert to such derangements as affect the coal measures, and endeavour to explain their nature by examples which have either come under my own observation in the discharge of professional duties, or been communicated to me in like manner; and while I shall endeavour to be as clear and concise as I can, I most humbly throw myself on your kind indulgence for any slips or hitches other than those I am to speak of.

The troubles which occur in the Scotch coal-field may be divided into four classes :

First.-Dislocations, faults, or slips;

Second.-Dykes composed of different materials—clay, sandstone, loose stones, and trap;

Third.-Wants and nips (these are total absences of the mineral for certain distances);

Fourth.-Local changes and aberrations of the stratification of the mineral field.

The terms dislocation, hitch, slip, step, and fault, are nearly synonymous. They are essentially cracks or breaks in the strata, by which the line of deposit is shifted above or below its former level, and the continuity of the strata interrupted.

That the strata forming the coal measures were at one time