from the number of men employed, both on the ground and for fixing the
trusses in their position aloft, and from the rapid progress so many hands
made. Each gang of men was managed by a foreman, who was obliged to issue
his orders through a speaking-trumpet, to enable his voice to be heard in
the din caused by the other works going on around. Besides the two large
gangs of men engaged in the hoisting of the trusses, other smaller gangs
were at work at different points getting up the columns and girders. In one
part, the roofing of which was completed as early as practicable, a crowd
of carpenters were preparing the Paxton's gutters and other portions of the
work. In another place, as soon as a sufficient space could be roofed over
and a temporary floor laid, various parts of the machinery we have already
described were fitted up and worked by portable steam-engines. Of these
there were three in different parts: one drove the machinery for finishing
the sash-bars, gutters, ridges, &c.; another worked the drilling, punching,
and other machinery connected with the iron-work; and a third was used for
working circular saws.
Of the number of trusses that were hoisted as above described, in only one
instance (and that the first) was the result otherwise than perfectly
successful. The first truss was raised by its ends, instead of from the
centre; but that method was afterwards abandoned, from the difficulty of
maintaining the truss in an upright position during its ascent; which was
important, as, if it turned on its side, its lateral strength was not
sufficient to prevent it from bending, which would have destroyed the
joints of the work.
One of the tall masts was worked on each side of the transept, from the
centre to the ends of the building, being maintained constantly in an
upright position, while traversing from point to point, by alternate
slackening and hauling up of the ropes which steadied it; and it was
curious to witness the motion of these tall giants, as they slowly
progressed from one point to another, in the performance of their important
office. Stout planks were laid along the ground, upon which the foot of the
mast was forced forward by crowbars and levers; the planks served also to
distribute the weight, which would otherwise have sunk the end into the
ground. As many as seven trusses were hoisted in one day by each derrick,
which had therefore to travel a distance of 168 feet.
So careful were the men, under the direction of the manager (to whom was
intrusted the active superintendence of the whole erection of the
building), that no accident of importance occurred in these difficult
operations.
[Illustration: HOISTING THE 72-FEET TRUSSES.]
Provision for Expansion of Girders.
In connexion with the fixing of the girders, it may be desirable to mention
the provision that was made for the expansion and contraction of the iron,
which in so great a length as that of the building might have otherwise
produced results prejudicial to its stability.
Between the projections cast on to the connecting-pieces and those
projecting from the ends of the girders which they were made to clip,
sufficient space was left for the introduction of oak keys, by driving in
which the girder was fixed in its place, whilst the compressibility of the
wood left sufficient play for the expansion of the metal. In describing the
girders, it was mentioned that in the upper and lower flat flanges small
sinkings were cast near the ends. Corresponding with these sinkings, a
notch was left in the projection which came out from the connecting-piece;
and when the girder was put into its place, iron wedges were driven in
between the notch and the sinking, by which means any lateral motion of the
girder was prevented. It was a great advantage to have the means of fixing
the girders of so simple a nature, as any arrangement presenting the least
complication, or requiring great nicety, would have materially retarded the
progress of the work.
The wrought-iron trusses were held by the connecting-pieces in a similar
manner to the cast-iron girders; but, as an additional security, bolts were
passed through holes provided in the standards at the ends, and through the
connecting-pieces, where they were screwed up with nuts.
The raising and fixing of the extra-strong roof-trusses crossing the main
avenue near the side of the transept required particular care, from their
great weight; the heaviest being, as we have before mentioned, no less than
eight tons. These trusses were the first that were fixed across the central
avenue, and about 150 men were engaged in the hoisting of each one. They
are secured to the columns by four strong bolts passing through the
end-standards.
In order to provide additional support for the great weight brought upon
the last-mentioned trusses by the transept roof, extra columns were
introduced underneath them. These were built up in storeys corresponding
with those of the other columns, with which they were connected, at the
levels of the girders, by bolts and straps. A cast-iron shoe, fixed on the
top of the columns, provided a bearing for the ends of the truss. The
columns just described project slightly into the main avenue from the line
of the other columns; and this is the only instance in the interior of the
building of the iron columns occurring at a less distance than twenty-four
feet apart.
Glazing the Roof.
We have now traced the erection of the building up to the level of the
roof, in which it will be readily conceived the operation of glazing was
one of extreme difficulty, there being no scaffolding to aid the workmen in
conducting their operations. When the glazing was first commenced a light
scaffolding was suspended from the rafters; but this was found to be too
tedious and troublesome a method of proceeding for so large an extent of
roofing. It was, moreover, of great importance that some means should be
devised for completing this part of the construction independently of the
weather; a matter of some moment, when it is remembered that the work had
to be done in the winter, when in our climate such operations are liable to
be very much impeded by heavy rain. The arrangements made to meet this
difficulty, as well as some others for carrying on the works, are very
clearly described in a paper by Mr. Digby Wyatt, read at the Institution of
Civil Engineers, on the 14th January, 1851, from which we quote some
passages, by permission, for the benefit of our readers.
With reference to the means employed for glazing the roof he says: "To
effect this purpose, a travelling stage was devised by Mr. Fox, which
superseded the necessity of any scaffolding for glazing, and by means of
seventy-six of these machines nearly the whole of the work has been
executed. The stage was about eight feet square, and rested on four small
wheels travelling in the Paxton's gutters. It thus embraced a width of one
bay of eight feet of the roof, with one ridge and two sloping sides. Each
bay in width required, therefore, a separate stage."
"Each stage was occupied by two workmen, and was covered by an awning of
canvass stretched over hoops, to protect them in bad weather, and was
further provided with a box on each side to contain a supply of glass. The
sash-bars and other materials were piled upon the stage itself, the centre
of the platform being left open for the convenience of hoisting up
materials, for which purpose there was a small iron arm with a single block
pulley."
[Illustration: GLAZING-WAGGON, FOR FLAT ROOF.]
"Whilst working, the men sat at one end of the platform (the ridge having
been previously fixed in position by means of the extra-strong sash-bars),
and they fixed the glass in front of them, pushing the stage backwards as
they completed each pane. On coming to the strong sash-bars previously
fixed, they temporarily removed them to allow the stage to pass. In this
manner each stage travelled, uninterruptedly, from the transept to the east
and west ends of the building, and the glaziers were enabled to follow up
the previously-fixed work very closely. The average amount of glazing done
by one man per day was fifty-eight squares, or about 200 superficial feet;
and the largest amount done by any one man in a working-day was 108
squares, or 367 superficial feet."
The mode of fixing the squares of glass was this: a sash-bar having been
nailed down between the ridge and the gutter, the workman inserted one long
edge of a square of glass into the groove in the sash-bar, he then placed a
loose bar against the other long edge of the glass and brought the whole
down to bear upon the ridge and gutter, the second sash-bar fitting into
the notches prepared for it; the glass was then pressed up a little, in
order to insert its upper edge into the groove in the ridge, and the
workman then filled in the grooves on the outside of the glass with putty,
the lower edge of the glass having been also bedded on putty where it bears
on the edge of the gutter. The ends of each sash-bar were fixed with a nail
driven into the holes previously drilled.
Stage for Repairing Glass.
As it might naturally be expected that out of the thousands of panes of
glass employed, particularly in the flat roof of the building, many would
be broken in the course of the works, subsequently to their being fixed, it
was necessary that a ready means should be devised for repairing any such
damage, as the glazing-waggons used for the first execution of the work
would not be available for that purpose. A light stage was therefore
constructed, travelling with wooden wheels upon the ridges instead of in
the gutters; and from this the men were able to perform their work without
walking along the narrow gutters, which would have been attended with much
risk. This stage was also used for fixing the canvass on the outside of the
roofing, where it is nailed along the ridges, and allowed to bag down
slightly between them. The object of the canvass, which covers externally
the whole of the roof except the transept, is twofold: it preserves the
glass from damage, and also protects the objects exhibited from the direct
rays of the sun, which would, of course, in many instances, be very
prejudicial; for the latter purpose the upright sashes on the south side
are also covered with canvass on the inside.
Hoisting the Ribs for Transept Roof.
One of the most interesting operations which attracted the attention of the
numerous visitors to the works was the raising the ribs for the
semicircular roof of the transept, the description of which we give from
Mr. Wyatt's paper:--
"The operation about which most anxiety had been felt was the hoisting of
the arched ribs of the transept. These ribs were constructed on the ground
horizontally, and when completed with all their bolts, two of them were
reared on end, and maintained in a vertical position, at a distance of
twenty-four feet from each other, by guy-ropes. As the ribs singly
possessed little lateral stiffness, they were framed together in pairs with
the purlins, intermediate small ribs and diagonal tie-rods, forming a
complete bay of the roof twenty-four feet long; two complete sets of
temporary ties were also introduced to provide for the strains incident to
the variations in position of the ribs during the hoisting. The feet of the
ribs were bolted on to a stout piece of timber, and the lower purlins
strutted up from the same." In this state the framework is shown in the
engraving.
[Illustration: A PAIR OF RIBS PREPARED FOR RAISING.]
"The whole framework was then moved on rollers to the centre of the square
formed by the intersection of the transept and the main avenue, where it
was afterwards hoisted. All the ribs were landed over this square, and were
afterwards moved on a tramway formed of a half baulk of timber constructed
over the columns on either side of the transept, at a height of about four
feet above the lead-flat. The hoisting-tackle consisted of four crabs, each
one being placed on the side of the transept opposite to the part of the
ribs to be lifted by it, so that the men at the crabs might watch the
effect of their exertions with greater convenience."
"The hoisting-shears were placed on the lead-flat immediately over the deep
trusses of seventy-two feet span; each set consisted of three stout
scaffold-poles, lashed together at the top, and footed on planks laid
across the flat, and secured by the necessary guy-ropes. The hoisting-rope
passed from each of the crabs across the transept horizontally, to a
leading block attached to the foot of the opposite angle column of the
square; it then passed up to a treble block fastened to the shears on the
flat, and from thence down to a double block secured by chains to the
bottom part of the ribs."
[Illustration: Hoisting the Ribs for the Transept Roof.]
"There was a peculiar difficulty to be overcome in this operation, which
arose from the circumstance that the width of the framework was greater
than that of the transept, the extreme width of the framework to be hoisted
being seventy-four feet, and the clear width apart of the trusses above
which it had to be hoisted being only seventy-one feet four inches. It was
therefore necessary to raise one side to a height of thirty-five feet
before raising the other, so as to diminish the horizontal width of the
whole, the diameter of the semicircle being maintained at this angle; the
whole was then hoisted, until the highest end could clear the tramway."
This accounts for the slanting position in which the ribs are shown in the
view given.
"The foot of the ribs on one side was then passed over the tramway
sufficiently to allow the other side to clear the opposite truss; after
which the whole was hoisted to the full height, and rested on rollers of
hard wood placed between the sills attached to the framework and the
tramway, by means of which it was moved to its permanent position. There it
was again raised by another set of shears, while the sill and tramway were
removed from under it; and the ribs were then lowered into the sockets
prepared for them, formed by the continuation of the columns above the
level of the lead-flat."
"Each successive pair of ribs was fixed at a distance of twenty-four feet,
or one bay from the preceding one; and the purlins, &c., were fixed in the
intervening space without any scaffolding from the ground, by means of
jointed ladders, which were adjusted to the form of the roof."
The first pair of ribs was hoisted December 4th, and the eighth pair on
December 12th. The operation, which was one of great excitement and
considerable anxiety, was personally superintended by the contractors,
aided by their most able foremen and assistants; and a crowd of visitors,
including many of the illustrious promoters of the undertaking, watched
with intense interest the steady ascent of the apparently unwieldy piece of
construction, and every spectator seemed astonished at the mechanical
regularity with which the whole operation proceeded. It took about one hour
to raise a pair from the ground to the level of the lead-flat, and the
whole was done without any accident whatever. About sixty men were employed
in the hoisting, there being eleven men to each crab, and the remainder on
the lead-flats.
Glazing the Transept Roof.
The semicircular form of the transept roof rendered it necessary to adopt a
different mode of operation for glazing it to that used in the horizontal
portion. A stage, thirty-two feet long and about three feet wide, with a
protecting rail at the side, was constructed, so that it rested upon
rollers, travelling on the ridges. It was slung by ropes from the crown of
the arched roof, and could be raised and lowered at pleasure. It
accommodated eight workmen, with the necessary quantity of materials in
sash-bars and glass; and they thus performed, with ease and rapidity, an
operation which before the fitting-up of the stage appeared at least
extremely difficult, and to the uninitiated next to impossible.
[Illustration: STAGE FOR GLAZING THE ROOF OF TRANSEPT.]
The men commenced fixing the glass at the bottom or springing of the arch,
and as they completed their work the stage was raised at intervals by
labourers stationed on the lead-flat. A portion of the glazing at the crown
of the arch was effected by men working on a light scaffold, suspended
within from the temporary ties mentioned as having been attached to the
ribs; whilst those upon the stage worked upwards till they joined the
portion done from the top.
The Painting.
A portion of the work which necessarily occupied a very large amount of
time was the painting, which was necessary for the preservation of all the
parts, as well as for their appearance; and when it is considered that
every portion required to be gone over four times, it must be evident that
it was highly desirable to adopt some means for facilitating the operation.
It was found that the sash-bars of the roof, being in short lengths and of
small dimensions, could readily be operated upon by some mechanical
contrivance.
[Illustration: THE SASH-BAR PAINTING-MACHINE.]
A wooden trough was made sufficiently long to receive the sash-bars, and
this was filled with paint; a number of the bars were then put into it, and
upon being taken out separately, they were passed through a frame into
which a set of brushes were fixed in such a manner as to clear off all the
unnecessary paint. Two small brushes, placed where the bar first entered
the frame, cleared out the grooves. One workman pushed the bar in at one
end of the frame, which was about two feet six inches long, and another
drew it out at the other end, where a trough was placed to receive any
droppings of paint. The bars were then stacked upright, until they were
sufficiently dry for the next coat. The first coat only was put on by this
apparatus, the second being done in the ordinary manner, and the last not
till after the work was all fixed in its place. By means of this apparatus
a workman could perform at least ten times the amount of work done in the
ordinary way.
[Illustration: THE FRAME-WORK WITH BRUSHES.]
The finishing the painting of the various parts of the roof internally,
after they had been put together, was very ingeniously managed, so that
while the workmen were able to work with ease to themselves, the
scaffolding on which they stood required no supports from the ground, where
they would have been much in the way of other operations; loops of
wrought-iron were hooked on to the roof-trusses, and by means of these a
perfect cloud of scaffold-boards was suspended, enabling between 400 and
500 men to be at work at one time. The roof of the main avenue,
particularly, presented a very singular appearance, as nearly one half of
the entire length was thus covered at one time, and a crowd of painters
were at work over the heads of many, perhaps unconscious exhibitors, who
were arranging their goods undisturbed below.
The Hand-rail Machine.
One of the mechanical contrivances which were put up on the ground during
the works, for saving labour and increasing the rapidity of production,
remains to be mentioned; it was contrived for turning out the rounded
mahogany hand-rail for the gallery railing as well as that for the
staircases.
The mahogany being supplied in slabs of the requisite thickness, these were
first cut up by circular saws into pieces of a square section, and the
angles of these were then bevelled off by the same means; the lengths were
afterwards transferred to the hand-rail cutting machine to be rounded.
[Illustration: THE HAND-RAIL CUTTING MACHINE.]
[Illustration: PART OF HAND-RAIL MACHINE.]
The principal portion of the machine consists of a hollow cast-iron
cylinder, round which a strap may be passed to drive it. At one end of this
cylinder four cutters are fixed, so that a piece of wood passing between
them and through the cylinder, as it revolves, is rounded off to a true
circular form of section, and is turned out so smoothly finished as to
require scarcely any further work upon it before fixing. In advance of the
cutters pressure-rollers are placed, furnished with teeth; and these, as
they are turned round by a cranked handle, seize upon a piece of mahogany
and force it forward against the cutters, which form, as it were, the jaws
of the hollow cylinder, which thus seems to be constantly swallowing
lengths of rough mahogany, which escape from it finished. The wooden rail
is passed up to the cutters along a groove, the end of which is shown in
the small engraving; and opposite each end of the revolving cylinder
springs are fixed, which prevent the rail from shifting its position. The
hand-rail was all turned out in 21-feet lengths, of which about thirty were
completed in the day.
General View of the Works.
We have mentioned that the actual commencement of the building was made by
fixing one of the columns on the 26th of September; and, within a few
weeks, more than a thousand men were at work, though, from the great extent
of the ground they were spread over, it was difficult to estimate their
number, which was, however, made apparent by the rapidity with which the
building began to grow. The place presented an animated and interesting
scene, which attracted a great number of visitors; and crowds of the fair
sex were not deterred by the rough state of the ground from endeavouring to
satisfy their proverbial thirst for knowledge. In one part of the ground
might be seen the putting together of the wrought-iron roof-girders to the
deafening tune of more than a hundred hammers; in another place gutters
were being put together by the mile, for which some hundred or two of
sawyers were cutting up ship-loads of timber. Three portable steam-engines
in various parts were driving the different machinery already described,
which, however, was mostly grouped in one place near the transept. The
central avenue formed, of course, the great thoroughfare, where teams of
horses were constantly passing, dragging the slender columns, or
unwieldy-looking girders, to their places, while other teams were engaged
in running them up to their final position. Over-head, too, the glaziers'
waggons, dotted about the roof, seemed to be running on some new aerial
railways; in every direction that the eye turned the busy scene extended.
For carrying on these extensive works an immense number of men were
necessarily employed on the spot, besides those occupied in preparing the
various parts at different places. The greatest number of men on the ground
in any one week was 2,260; and the season of the year frequently rendered
it necessary for the workmen to continue their labours after dark, which
they did partly by the light of huge bonfires of shavings and odd scraps of
wood. The effect of these great fires, which were generally lighted in some
part of the main avenue, was exceedingly grand. The light of the tall
flames was reflected from the glass of the roof far away into the darkness
which concealed all the other parts; whilst occasionally a lantern carried
by a workman engaged in fixing the upper columns, or some part of the roof,
glimmered like some new star.
On one occasion, when the greatest efforts were being made to push on the
progress of the works, no less than twelve large bonfires lighted the men
at their midnight toil; and had the building been formed of combustible
materials, a passing observer would have imagined that the whole was in
flames.
Paying the Workmen.
The process of distributing their wages among so large a number of men, on
every recurring Saturday evening, was one which could only be effected
within a reasonable time by some systematic arrangement; and to such
perfection was this brought in the course of the works, that the whole
number of 2,000 men or upwards were sometimes paid in little more than an
hour; though at first it occupied a considerably longer time.