in contact with the roller marked F, the projecting points on which so far seize it as to propel it forward to meet the rapidly revolving set of cutters marked A. Passing onwards to B, it is subjected to a second action. By C a third operation is performed, and in passing through D, a perfect form is given to the piece of timber. Thus, while, the end beyond D presents the perfect section of a Fig. 20.

finished gutter, the other end, which has not yet passed the set of cutters at A, remains in its original square form. In fig. 22, a vertical section is given, exhiFig. 22.

The Paxton gutters-how

completed for use on the ground.

biting the precise angle at which the cast-iron blocks are made to revolve, and the cutters to clear away the timber before them. O shows the section of the gutter acted on by the cutters, N the holdfast by which the gutter is kept in its place during the operation. By the use of this machine three feet of gutter can be made per minute, and, working night and day at this rate, the whole quantity required was completed in two months.

The Paxton gutters, thus prepared, were delivered on the ground, and after having been carefully examined, and the defective ones removed, they were conveyed to other machines (vide fig. 23), fixed upon the ground, by means of which they were finished ready for use. A large circular saw, the spindle of which could be raised or depressed by the action of a lever, had fixed in the centre of one of its sides two gouges, adapted to produce, by rapid revolution, a semicircular groove. A frame, the exact length of the gutters, was fixed at right angles to the

Fig. 23.

plane of this saw. In the centre of this frame a species of chair was constructed,
capable of turning round, and a shoe was fixed at the extremity of the frame farthest
from the saw. The end of a gutter about 24 feet long was thrust into this shoe,
and its middle supported by the chair already mentioned. The end nearest to
the saw was then pressed down, and secured by an iron strap. Thus retained in
position, it was necessarily bent to precisely that camber arranged to be ultimately
given to it by suspension-rods and struts. The circular saw, revolving rapidly,
was then made to descend until its edge came in contact with the end of the
gutter, which it cut to the precise length required, and at exactly the right
angle. The axis of the circular saw
was then still further lowered down,
until the gouges fixed on its side cut
their way through the gutter, making
a semicircular groove through its
depth. One end being thus scooped
out, the gutter was released from its
position, turned round, and secured
in a contrary direction in the shoe at
the opposite extremity of the sup-
porting frame. The other end of the
gutter, thus presented in its turn to
the saw, was then subjected to a
similar process, after which it was
removed, perfectly ready for the at-
tachment of its iron bowstring.

A machine of somewhat similar construction (though much simpler) to that by which the Paxton gutters

he ridges.

Mr. Paxton s

improvements in

the manufacture

were made, brought the ridges to their proper form. In the course of numerous experiments which Mr. PAXTON had commenced as The sash-bars, early as the year 1828, the great necessity for providing some machine by which a quantity of sash-bars might be speedily and economically cut, was forcibly of, generally. impressed upon his mind. In the paper we have already quoted, Mr. PAXTON thus describes the origin of machines of this description:-" In 1837 the foundations "of the great conservatory (at Chatsworth) were commenced; and in constructing "so great a building, it was found desirable to contrive some means for abridging "the great amount of manual labour that would be required in making the "immense number of sash-bars requisite for the purpose. Accordingly, I visited "all the great workshops of London, Manchester, and Birmingham, to see if anything had been invented that would afford the facilities I required. The only "apparatus met with was a grooving-machine, which I had at once connected with "a steam-engine at Chatsworth, and which was subsequently so improved as to "make the sash-bar complete. For this apparatus the Society of Arts, in April, " 1841, awarded me a medal, and this machine is the type from which all the "sash-bar machines found in use throughout the country to the present time are "taken. As the conservatory was erected under my own immediate superin"tendence, I am able to speak accurately as to the advantages of the machine. "It has, in regard to that building alone, saved in expenses 1,4007. The length of " each of the bars of the conservatory is 48 inches, only one inch shorter than those

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"of the Exhibition Building. The machine was first used in its present form in August, 1838, and its original cost, including table, wheels, and everything complete, was 207. The motive power is from a steam-engine employed on the premises for other purposes, and any well-seasoned timber may be used. The "attendants required are only a man and a boy, and the expense of the power required for it when in use is comparatively trifling. The sash-bars may be "made of any form, by changing the character of the saws. There is one par"ticular feature in working the machine, namely, that the bars are presented to "the saws below the centre of motion, instead of above it, as is usual; and to the "sides of the saw which are ascending from the table, instead of those which are descending. These arrangements were necessary to suit the arrangement of the teeth to the grain of the wood; for when the bars were presented to the saws "in the usual way, the wood was crushed, instead of being cut and cleaned. It is "essential that the machine should revolve 1,200 times in a minute to finish the "work in a proper manner."

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66

Sash-bar machine

used for the

building.

We shall now proceed to describe the modification of this machine, which is due to the inventive powers of Mr. BIRCH, of the Phoenix saw mills, near Cumberland-market, Regent's Park, with whom a contract was entered into by Messrs. Fox and HENDERSON for the supply of all the sash-bars for the roof, the upright bars for the vertical lights, and the ridges. Two of the principal points of difference between Mr. BIRCH's machine and that described by Mr. PAXTON are, that revolving cutters are substituted for saws, thus obviating difficulties incident to the grain of the wood; and that, by the addition of a second set of cutters, a plank passed between them is operated upon on its upper and under surfaces at the same time. In fig. 25 is shown a cast-iron block (somewhat similar to those previously described in connection with the gutter-cutting machine), to which are attached a variety of cutters. The rapid revolutions of the spindle (A fig. 26) operate upon the planks submitted to the action of the cutters, in the manner shown in fig. 28. So soon as the plank, presented by the feed-roller, has been operated upon by the rapid revolution of these miniature adzes, it is carried on by the roller C, and is subjected to the action of circular saws of varying diameters, the lesser of which cut just sufficiently deep to form the groove for the

glass, while the larger pass completely through the plank, and divide it into four finished sash-bars. In figs. 24 and 28 is represented the mode in which the sashbars for the vertical lights are made, the hatched lines indicating the parts removed; and in fig. 27, the way is shown in which the sash-bars for the roof have been cut. Modifications in the cutters affixed to the spindle A, fig. 26, produce the variation in form.

how finished on

As delivered at the building, the sash-bars were cut approximately only to The sash-barstheir length, and in order that it might not be necessary to execute any carpen- the ground. tering operation on the roof, it was requisite that they should be adjusted on the ground, ready for fixing. An arrangement of circular saws, set at the angles requisite to cut the ends of the sash-bars to accord with the pitch at which they would have to be presented for attachment to the ridges, served at once to cut a large number passed between them to a perfectly uniform length, and to form the necessary rebate for notching down upon the gutter edges.

To ensure the gimlet-holes necessary for nailing down the sash-bars being made with perfect regularity, a row of five gouges were set in motion by a band from an adjacent steam-engine, passing over a series of drums. The sash-bars, placed at a proper angle to them, were moved along by boys, in the manner shown in fig. 29, and presented to the points of the gouges, by the rapid revolution of which the necessary nail-holes were pierced.

for painting the

It yet remained to paint these sash-bars, and even for that purpose the inge- The machine nuity of Messrs. Fox and HENDERSON provided mechanical assistance. A number sash-bars. of brushes were arranged in a frame, at right angles to one another, in such a manner that their bristles would just admit of the passage between them of a sashbar. In a trough filled with colour a number of sash-bars were immersed, and one of them being lifted from it, loaded with colour, and presented to an aperture at one end of the series of brushes, it was passed through them to a corresponding aperture at the other end; by which process the whole of the superfluous paint was removed, and the sash-bar drawn out as neatly painted as it could have been by the workman's hand. This machine is represented in use in fig. 30.

Morticing machine employed.

The making of the glass.

To facilitate the putting together of the sash-frames and sash-bars, considerable use was made of a machine for making mortices and tenons, patented by Messrs. FURNESS & Co., of Liverpool.

While these various machines were busily operating in the preparation of the necessary framework to receive the glass, Messrs. CHANCE BROTHERS & Co., of Smethwick, near Birmingham, to whom the contract for its supply had been committed, were not less actively employed. The large size of the sheets required (4 feet 1 inch by 10 inches), and the extraordinarily short time within which the

Progress made in framing roof trusses;

immense quantity necessary had to be supplied, demanded the employment of numerous additional hands, and workmen had to be sought for from abroad to assist in the completion of the order within the requisite time. The mode of manufacturing the description of glass employed is a great improvement on the old system of crown-glass making; as by it the variation of the substance occasioned by the thickness of the glass, as it approaches the bull's-eye, is completely avoided. In the manufacture of sheet glass, the workman, having taken up a lump of glass on the end of his pipe, alternately blows, swings his ball of glass to and fro, and rolls it upon a metal table until it assumes the form of a long cylinder; the ends being then taken off, and the cylinder cut in the direction of its length, the sheet of glass falls down, is flattened to a perfectly true face, and is then trimmed off and finished.

During the preparation of the materials necessary to commence the construction of the Paxton roofing, active progress had been made in the framing of the wrought-iron trusses requisite to span the central 72-feet nave, and the 48-feet avenues on each side of it. A steam-engine of 6-horse power gave motion to drilling, punching, and cutting machines, represented in figs. 31 and 32. By ing, and cutting, means of these, the necessary pieces of bar-iron were adjusted to their requisite

by means of drilling, punchmachines;

lengths. The holes for rivetting having been marked upon them with templates, were punched out, and any larger perforations necessary for extra-sized rivets, drilled. The various parts, thus prepared for combination, were then arranged upon platforms, and the holes in the various portions being made to correspond,