plate, and the latter on brass plate; and that, in consequence of iron being less ductile than brass, the iron must go through a greater number of operations.

The iron must, it appears, be annealed by fire from time to time, as it may require, at suitable stages in the course of going through these operations. About two or three times of annealing, during the course, are said to be sufficient. To prepare the brass or other metal, (such, for instance, as German silver,) which is to form the exterior surface of the ball part of the knob, a square piece of thin sheet brass or other metal, of a suitable size, is cut out with shears, and then that square piece is stamped in the same manner as before described respecting the iron, by a like series of operations, performed in the same or similar dies, and with tools corresponding thereto, except that, in consequence of the ductility of brass or German silver, it is not requisite to subject them to so many successive operations as prescribed for iron.

The mode above described of preparing the deep cup of brass or other metal is stated to be the same as is usually practised in the manufacture of hollow knobs of the ordinary kind, which are made from brass plate without iron, except that the plate of brass or other metal may, in manufacturing according to the present patentee's improvement, be thinner, if desired, than could with propriety be used in manufacturing knobs of the ordinary kind, of brass plate without iron.

The corresponding deep cup of brass or other metal being thus formed, the iron cup is put therein, the border edge of the latter being first clipped round with a pair of clipping tools, to remove the superfluous metal, bringing the edges of the two cups nearly to correspond.

Then the two cups together are forced through a circular hole in a steel ring, by a corresponding tool urged by a fly-press, and thereby the sides of the two cups are drawn in, or contracted to a cylindrical form, and the brass caused to adhere very closely to the iron.

The circular border edge of the compound cup of brass lined with iron is then cut round with shears, so as to reduce the iron and the brass to an exact correspondence, and so as to give a true border edge to the compound cup.

The compound cup is then closed in, or so contracted at the border edge, around the mouth, and at the parts of the sides adjacent to that mouth, as to be of suitable size to receive the large part of the neck of the knob. This closing in of the mouth is performed in the usual manner of closing in, as practised in the manufacture of hollow knobs

from brass plate without iron, that is, by means of a pair of closing tools in the fly. press, which force the large open mouth of the cup into a concave hollow die, of a suitable concave shape for gathering in the border edge around the mouth, and also part of the sides adjacent to the mouth, to the proper shape. The preparation of the hollow ball part of the knob is now completed, except that, if the border edge around the contracted mouth be not quite true and smooth, it may be made so by means of a revolving conical tool, furnished with cutting-teeth around its conical surface, such tool being of the nature of a countersink of large size. This tool or countersink may be mounted in a lathe, by affixing it at the end of the revolving spindle of the lathe, so that the countersink will be turned round, and by holding the hollow ball in the hand, and applying the contracted mouth to the revolving countersink for an instant, the border edge of the mouth will be cut by the revolving countersink, and may thereby be rendered truly circular and smooth, and bevelled internally to suit the conical form of the cutting part of the countersink.

If the cutting of the border edge of the compound cup with shears has been truly performed (or it may be filed smooth and true after cutting with shears,) then the border edge of the contracted mouth will, of itself, assume a proper level shape during the contraction, and will continue to be sufficiently smooth and true without cutting that border edge by a countersink, which may therefore be used or not according as may be found requisite.

For preparing the neck part of the knob the hollow iron part for lining the neck may be made of cast-iron, cast into the intended shape with a square hole through the centre of it, and a groove around each end of it, for the purpose of fastening the several parts of the knob together.

To prepare brass or other metal for the exterior surface of the enlarged part of the neck of the knob a piece of the same kind of sheet brass or other metal, as has been used for making the cup, is to be cut out in a square shape, and that square piece is to be stamped in a concave die, so as to bring it (by one or more operations of stamping, as may be requisite,) to the proper form. Then the exterior border of that piece of brass, or other metal, is to be clipped true with shears, and a central hole is to be pierced through it, with a pair of cutting-out tools in the flypress, that hole being of a proper size to fit tight over the neck part, and then the neck piece is to be forced on to the iron casting, by pressure of suitable tools in the fly-press, so as to make it apply closely thereto.

And in order to prepare brass or other metal, for the exterior surface of the small or neck part, a piece of tubing of brass or other metal, of a suitable size to fit on that neck part, is cut off to the requisite length to form a ferule, which is forced on around the iron, the end of the ferule applying against the piece around the central hole.

To form the collar, or shoulder, around the end of the neck, the neck with the neck-piece, and the ferule upon it is to be put into a mould formed of sand in the usual manner practised by brass-founders, so as to leave a cavity in that mould around so much of the end of the iron neck as protrudes beyond the ferule, and melted brass or German silver, or other metal is to be cast around the said protruding end of the iron, and around the groove thereof, so as to form a collar, or shoulder, which, by that means, becomes firmly fastened around the neck.

The two parts for the knob being thus prepared, (viz.) the hollow ball part, and the neck part, those two parts are to be put together by means of a pair of mounting tools, in the same manner as is commonly practised in manufacturing hollow knobs of brass without iron; that is to say, the neck is dropped into a hollow tool, which permits the collar to go down into the hollow of that tool, and the concavity of the said tool above that hollow affords a resting place for the enlarged part of the neck, and then the hollow ball is dropped with its open mouth over the enlarged part of the neck, and the part of the ball around the mouth thereof, will also find a resting place in the concavity of the tool, and in that position of the parts the border edge of the mouth of the ball will be opposite to the groove around the enlarged part of the neck, and then by pressure of another suitable concave tool upon the concave part of the ball opposite to the mouth, by force of the fly-press, the part surrounding the open mouth, will be gathered in more closely, and that mouth will be further contracted, so as to interlock its border edge very firmly into the groove, whereby the two parts of the knob become united firmly together, which, being the same mode of union, and being performed with similar tools, and in the same manner as commonly practised in manufacturing hollow knobs of brass without iron does not require further explanation.

The knob, made as before described, is then finished by dressing and burnishing the exterior surface in a lathe in the usual manner, and the collar, or shoulder, is turned true.

The tools employed in the process before described are of the ordinary kind, and such as are well known; and no claim of new invention is made in respect of such tools, nor in the mode of using the same.

Claim." I do hereby declare, that the new invention, whereof the exclusive use is granted to me by the aforesaid letters patent, consists in the improvement hereinocore described in manufacturing hollow metal knobs for the handles of door and other locks; the essential character of that improvement being that of forming an interior lining of stamped iron-plate to the hollow-ball part of the knob, and (in case it is preferred) an interior of cast-iron to the neck part of the knob, in order, by means of such stamped iron, and such cast-iron (if the latter be used) to give support to the brass, German silver, or other metal, whereof the exterior surface of such knob, is, or may be composed."

ANDREW KURTZ, OF LIVERPOOL, MANUFACTURING CHEMIST, for certain improvements in the manufacture of artificial fuel. Rolls' Chapel Office, August 26,

1842.

The improvements which are the subject of this patent consist, firstly, in mixing with inferior coals such proportionate quantities of coke, (made from coals,) rosin, or naphthaline, with pitch, (made from gas-tar,) or other bituminous substance, as will equalize or counterbalance the combustible strength or evaporative power of such inferior coal with that of the best coal known or found in

"I

England and Wales. The proportionate quantities of superior combustible matters to be added to the inferior coals, in order to bring them up to the same standard of evaporative power as the best English or Welsh coal, must of course depend upon the inferiority of the coal to be improved, and as the British government standard for contracts for artificial fuel is, that one pound of fuel shall evaporate eight pounds of water, the present patentee takes that as his standard, and the following experiments are related, as showing the manner and proportions in which the addition of combustible matters must be made to inferior coal. have found," says Mr. Kurtz, "that the evaporative power of coals is as follows, (by way of illustration :) one pound of anthracite coal will evaporate eight pounds of water; one pound of best Welsh coals, 7 lbs. to 8 lbs.; one pound of Liverpool coals, called Smith's coals, 7 lbs. ; one pound of ordinary Liverpool coals, 4 lbs. to 6 lbs. Newcastle coals are similar in effect to Liverpool coals, so that it will be readily perceived, that where the best Welsh coal wants, as it were, one of superior combustible matter, ordinary or inferior coals will require four or more parts, and that the proportions must be suited and varied according to the ascertained quality of the coals when in a natural state."

The patentee claims, secondly, certain improvements in the application and use of certain machinery or apparatus, for the purpose of preparing or mixing the component parts of such artificial fuel, and forming or moulding the same into portable and convenient shapes or bricks for use, as follows." The natural coal is first to be ground small between an ordinary pair of horizontal grinding-stones, or in a grinding-mill, and is afterwards to be submitted to a drying kiln or apparatus, for the purpose of expelling all moisture from the coal. This drying apparatus is to be constructed with three chambers or compartments, say 12 feet long by 9 feet wide, and by 6 feet deep altogether. The flooring of these chambers should be of plate-iron, and somewhat dished or sunk in the middle, and also provided with a small aperture or opening, with a sliding door or cover to each. Between each compartment, and around these chambers, there are flues heated by the flame and air proceeding from the furnace or fire-place situate at one end of the apparatus, and each flue is to be provided with a damper, to regulate the heat as required. The upper

chamber or compartment is open at top, and may be called the reservoir; and in this the ground coal is to be placed, after being taken from the grinding apparatus, and heated or dried, so that the principal part of the moisture is evaporated; the sliding door is then to be removed from the opening in the bottom of this reservoir, and the coal raked or pushed down into the middle, or drying chamber. In this chamber the pulverized coal is also to be further dried and heated to about 300° Fahr., so that no moisture whatever remains. The sliding door is next to be removed from the aperture in the bottom of this chamber also, and the coal passed into the bottom, or mixing chamber. The pulverized and dried coal now lying in the lower chamber, the pitch, or other auxiliary combustible matter, is to be supplied through a trough, or other convenient means, and in such proportions as have been previously ascertained, and dependant upon the quality of the coal under operation, and after being sufficiently mixed together, by raking or otherwise, may be carried away in boxes or baskets to the next process. The composition or artificial fuel now being in a plastic state, is in the next place to be put into a machine very similar in form, and in the mode of operation, to an ordinary clay or pug-mill, as used by brickmakers. The form of this apparatus is similar to a vat, say of 6 feet diameter at top, and 8 or 9 feet deep, and tapering downwards. This vat or chamber is to be of cast-iron, and surrounded with a jacket or casing, to act as a steam

chamber, in order to keep the composition under operation in a continuous heated state, and thus capable of being more efficiently worked. For this purpose, a steam-pipe is supplied to the lower part of the casing of the pug-mill, conveying the waste steam from the steam-engine employed to work the whole system of apparatus, and which steam is to be passed off at the upper part of the vessel, the condensed water escaping below. The interior of this pug-mill is somewhat peculiar in its construction, and consists of a central upright shaft driven from gearing below, in connexion with a steam-engine or other moving power. Upon this shaft, of about 6 inches in diameter at the lower end, and tapering upwards to about 4 inches, are placed several pairs of arms or agitators, say about 6 pairs, about 9 inches wide, and reaching to within about an inch of the inside of the mill, at the top, and about 6 inches at the bottom, each alternate pair being set or fixed at right angles with the adjoining pair, and each arm placed at an angle of about 20° from the plane of the horizon, so that, as the shaft revolves, these arms or agitators will act as one continuous screw, and keep forcing or conducting the composition in the mill towards the bottom, simultaneously with the mixing and puggling process. A separate or independent arm is also fixed at the lower end of the shaft, and touching the bottom of the pug-mill. This arm is formed heliacally, and its outer end forces the composition or fuel in a continuous stream or course, out of an aperture or mouth-piece formed at the bottom of the mill. This aperture or trough may be shaped in any way, being open at the top, and having the sides and bottom square, so as to shape or form the plastic composition as it is being forced from the mill. Masses of this compound are now to be taken from the opening at the bottom of the pug-mill, and, whilst in a heated state, to be thrown or cast into square boxes or frames, the depth of an ordinary brick, when the plastic material will flatten as it cools, and spread itself evenly until it is confined by the sides of the frame; these frames may be large enough to contain a sufficient quantity to form 100 bricks or cakes of fuel. When the composition is sufficiently cooled, but not allowed to harden, it may be cut into forms or bricks, by means of a cylinder having a series of rotary cutters placed thereon, at given distances apart, and projecting from the cylinder so as to pass through the entire depth of the cake of fuel in the frames. This cylinder, or series of cutters, is to be passed across the composition in the frames lengthwise, and will thus cut up the fuel into lengths; and a similar

series of rotary cutters must be passed over the frames crosswise, and will thus form or cut the fuel into oblong squares or bricks. The frames must be well moistened with a strong solution of milk or lime, and the cutters and cylinders must also be well supplied with a similar solution from a saturated brush above, so that all sides of the bricks or cakes of fuel shall be coated over with lime, which will prevent their adhering to each other when packed closely together for use. The hardness of the fuel may be varied, and its capability of withstanding the effects of different climates, may be modified by a greater or lesser proportion of the pitch, or other emollient materials.

Claim."I claim as my invention the manufacture of artificial fuel, firstly, by bringing all natural coals to one uniform standard of combustible power or effect by artificial means; that is, by adding such proportions of coke, rosin, and naphthaline, with pitch, to inferior coals, as will equalize or counterbalance the combustible strength of the best coals known or found in England and Wales; and, secondly, the application and employment of the machinery or apparatus herein described for the purpose of preparing, mixing, and pressing or shaping sach artificial fuel into convenient portions, shapes, or bricks, for use."

INSTITUTION OF CIVIL ENGINEERS.

May 10, 1842.

"Description of a Flax Mill recently erected by Messrs. Marshall and Co. at Leeds." By James Combe, Assoc. Inst. C.E.

The mill described in this communication consists of one room, 396 feet long by 216 feet wide, covering nearly two acres of ground. The roof is formed of brick groined arches 21 feet high by 36 feet span, upon cast-iron pillars: an impermeable covering of coal-tar and lime is laid on a coating of rough plaster over the arches, and upon that is a layer of earth 8 inches thick, sown with grass. This immense room is lighted and ventilated by a series of skylights 13 feet 6 inches diameter; one at the centre of each arch. A vaulted cellar with brick pillars extends under the whole of the building, and contains the shafts for communicating the motion from a pair of engines of 100 horses' power, to the machinery in the mill; the flues and steam cases for warming and ventilating; the revolving fan for urging the air into the room, with the gas and water pipes, and the remainder of the space is appropriated for warehouses.

The heating and ventilating are effected by a large fan, which forces the air through the

pipes of two steam chests, each 10 feet long, and containing together 364 pipes of 3 inches bore: the temperature can be regulated by the quantity of steam which is admitted into the chests, or by allowing a portion of cold air to pass by without traversing the pipes; valves and doors in the flues permit any temperature which is desired to be obtained, or that degree of moisture which is essential for some part of the process of working flax.

The general details of the construction of the building are given, with the dimensions of the brick and stone work; the cast-iron pillars and caps, the wrought-iron tie-bars, with the reasons for adding a second set after the accident occurred to the first set: the mode of drainage from the roof; and the striking the centres of the arches, &c.

The total cost of the mill, including the ornamental stone front, was £27,443, which is stated to be about the same cost as that of a good fire-proof mill on the common plan; but as this mode of construction was novel to the workmen, it is probable that a second building of the kind would be less expensive.

The advantages resulting from the plan are, convenience of supervision, facility of access to the machines, the power of sustaining uniformity of temperature and moisture, the absence of currents of air which are so objectionable in other mills, the simplicity of the driving gear, and the excellent ventilation which is so desirable for the health of the workpeople.

The paper was illustrated by two drawings with a sheet of reference, and an appendix contained the result of some experiments upon the strain on the tie-bolts, the pressure on the arches, and the deflection of the bolts, &c.

Mr. Smith was much pleased to find this description of building brought before the Institution, as he had been the first to adopt it for a weaving shed of the extent of half an acre; the columns for carrying the arches were 30 feet 6 inches apart, and the skylights were 8 feet in diameter; some of the arches were of brick, with stone springers; others were entirely built with rubble stone well grouted, which latter mode of construction he found succeeded quite as well as brick: the settlement of the arches on striking the centres after standing four days was only ths of an inch: The arches were thickly plastered with common mortar and at first were only covered with a coating of boiled coal-tar pitch and lime ths of an inch thick, but as the wet penetrated, the thickness of coal-tar pitch was increased to ths of an inch, with a mixture of sharp

sand, which had proved perfectly watertight: for some months there was an appearance of moisture, which proceeded from the interior of the brick-work, as it could not escape outwards on account of the impermeable covering; after some time the copious ventilation carried off this moisture and the building became perfectly dry. Over the coal tar a thickness of earth laid, which is cultivated, and has proved a prolific garden: in severe weather the frost has not reached above 14 inch deep in the soil, while it has penetrated to the extent of 12 inches in other situations.

The construction of the floor is peculiar : it is desirable in such weaving sheds to have a boarded floor, to prevent the small parts of the machinery from being broken by falls, and also on account of the health of the persons employed; but the vibration of an ordinary wood floor is objectionable. In order to meet these views, a bed of concrete was laid throughout the building, a series of small deal spars 14 inch deep by 1 inch wide were set flush into the concrete whilst it was wet, and the whole surface was smooth plastered: upon this bed, when it was perfectly dry, a floor of boards 14th inch thick was nailed to the spars: it was found to combine the solidity of pavement with all the advantages of a wood floor, and there had not been any symptoms of dry rot; which might be attributed to their being no cavities left beneath the boards, the whole being firmly bedded down.

The ventilation was effected by tunnels beneath the floor, the covers of which wer pierced with a number of small holes to spread the air. The warming was accomplished by means of hot water circulating under the pressure of the atmosphere only, in "tubes of tin plate" 4 inches diameter; the temperature was very regular and perfectly under control. With one ton of coal per week the shed could be kept up to 70° during the winter.

The cost of this building was 30 shillings per square yard of area covered, which was less than the cost of Messrs. Marshall's mill, but building materials were much cheaper at Deanston than at Leeds. He expected that this mode of building would become more general as it combined many advantages, and whatever might be the first outlay in purchasing ground, the cost of which was the only inducement for constructing buildings of several stories in height, it would be fully compensated by the facility of superintendence alone, as in manufactories this was of the utmost importance.

These buildings would, he believed, be eventually used for agricultural purposes, and when engineering knowledge was more

directed to the processes of agriculture, good results might be anticipated: his attention had been particularly directed to the subject, and he was convinced of the necessity of concentrated superintendence which is not at present possible in the separate farmsteadings as they are now constructed: this might be apparently foreign to the subject before the meeting, but the range of engineering was so wide that it was difficult to say where it should stop.

Mr. Lindsay Carnegie as a landed proprietor could bear testimony to the importance of the connexion of engineering with agriculture, and to the advantages already derived from the improvements which had been introduced by Mr. Smith, who might be justly termed the father of the improved system of agriculture in Scotland.

Mr. Marshall explained that he was indebted to Mr. Smith for the suggestion of this mode of construction, which he had not hesitated to adopt, although all the plans had been prepared for mills of several stories in height he had been convinced of the superiority of the present plan and his expectations had been fully realized. There were, of course, some difficulties to be overcome and some experiments to try, all of which had not been successful, but in all the essential points this kind of building was superior to any other. An equality of temperature and a facility of imparting a certain degree of moisture to the air which was indispensable for spinning yarn had been perfectly attained.

A member inquired whether the arches were found to be perfectly water-tight? On some of the railways which were laid upon arches it had been found that asphalte had failed in rendering them impervious, and they were consequently useless, even for store-houses.

Mr. Marshall explained that a few leaks had occurred, particularly near the skylightframes, but they had been easily repaired and were now water-tight.

Mr. Combe found that a mixture of finelysifted engine ashes with the coal-tar pitch was better than lime. The depth of soil above the arches should be sufficient to prevent the heat of the sun from penetrating through the cracks to the pitch and forcing it up. He had recently examined the roof carefully and could only discover six indications of moisture penetrating; these had been easily repaired and all was now perfectly sound.

Mr. Field agreed with Mr. Smith in his estimation of the advantages of carrying on all manufacturing processes as much as possible under one roof and on one floor-great economy of time and labour would result, espe