and the largest establishment of the kind in Scotland, the total number
of retorts erected being about 750. The system in its most recent shape
was applied to four ovens, each of which had seven retorts, but which
number has since been increased to eight, owing to the space occupied
by the furnace in the ordinary settings being rendered available for
an additional retort in the new or "Siemens" setting. For each oven or
chamber of eight retorts there was erected a separate gas-producer,
so that even one set of eight retorts might alone be used if thought
necessary.

[Illustration: GAS RETORTS WITH REGENERATIVE FURNACES .--GLASGOW
CORPORATION GAS WORKS.]

In Figs. 1 and 2 of our illustrations, the general arrangement and the
relationship of the gas producer, the regenerators, and the retorts to
each other are clearly shown. It was a sort of _sine qua non_ of the new
method of firing the retorts that the producer should be in as close
proximity as possible to the place where the gaseous fuel was to be
used, and it was concluded that the most convenient situation would be
immediately in front of its own set of eight retorts, and with its top
on a level with the working floor of the retort house. To place it
in such a position meant a good deal of excavation, which was also
required, however, for the regenerator flues. The excavation was carried
down to a depth of 10 ft. below the level of the retort house floor, and
as a matter of course the operation of underpinning had to be resorted
to for the purpose of carrying down the foundations of the division
walls, which, together with the main arches and the hydraulic main, were
in no way otherwise disturbed. As in most new inventions, a good deal
of difficulty was experienced at first in connection with these gas
producers and heat regenerator furnaces; but by dint of application and