PORTION OF SASH-BAR DRILLING-MACHINE.
HE total length of these required was about sixteen miles. They are cut out of timber three inches square, in section, and are of the form shown in the diagram, with a groove on each side to receive the glass. This was also done by machinery which, with about five-horse power, turned out one hundred lengths of twenty-four feet in a day of ten hours, allowing the time for the necessary stoppages. After they had been delivered at the building, these ridge-pieces were cut to the exact lengths by means of the same apparatus used for the solid gutters which has already been described. At each end of the ridge-piece two holes were also drilled to receive dowells to connect it with the adjoining length. By no other than mechanical means could the immense number of holes thus drilled have been placed so exactly that those in the opposite ends of any two ridge-pieces should correspond precisely.
SECTION OF RIDGE AND ORDINARY SASH-BAR.
The different essential component parts of the roof having thus been described, we propose to take the different members of the construction in succession downwards.
UT first it may be mentioned here that the glass used throughout the building is sheet, on an average about one-sixteenth of an inch thick, and weighing one pound per foot superficial. This gives an aggregate weight of about four hundred tons for the whole of the work, the greater part of which was supplied by Messrs. Chance and Co., of Birmingham. Each square is forty-nine inches long and ten wide, the greatest length of sheet glass that has ever been made in this country. The manufacture of this kind of glass is of comparatively recent introduction into England, though practised for some time on the Continent; and the rapid progress made by the manufacturers alluded to must be in a great measure attributed to the wise removal of the fiscal burden on the article, made by the late Sir Robert Peel. That lamented statesman, with his usual foresight, doubtless contemplated that great social benefits would follow from that enactment; and it is, perhaps, not too much to say that, but for Sir Robert's enlightened measure, this "huge pile of transparency" would never have been reared.