of
the water bill of the plant. This was already of large proportions,
but it had suddenly jumped to the extent of several hundred dollars.
Investigation soon disclosed the fact that this water shield was one
of the main causes of the added cost of water. A little estimating
of the amount of water that can flow through a 1/2-in. pipe under
30-lb. pressure, in the course of a day, will show that this amount
at 10 cts. per 1,000 gal., can count up rather rapidly.

Figure 103 is a section through a portion of the furnace front and
shield showing all of the principal parts. This shield consists
essentially of a very thin tank, about 2-1/2 in. between walls,
and filled with water. Like other shields it is fitted with an
adjustment, that it may be raised and lowered as the work demands.
The tank having an open top, the water as it absorbs heat from
the flame will simply boil away in steam; and only a small amount
will have to be added to make up for that which has evaporated. The
water-feed pipe shown at _F_ ends a short distance above the top
of the tank so that just how much water is running in may readily
be seen.

An overflow pipe is provided at _O_ which aids in maintaining the
water at the proper height, as a sufficient quantity can always be
permitted to run in, to avoid any possibility of the shield ever
boiling dry; at the same time the small excess can run off without
danger of an overflow. The shield illustrated in Fig. 104 has been
in constant use for over two years, giving greater satisfaction
than any other of which the writer has known. It might also be
noted that this shield was made with riveted joints, the shop not
having a gas-welding outfit. To flange over the edges and then
weld them with an acetylene torch would be a far more economical
procedure, and would also insure a tight and permanent joint.

The water-cooled front shown in Fig. 105 is an absurd effort to
accomplish the design of a furnace that will provide cool working
conditions. This front was on a bolt-heating furnace using hard
coal for fuel; and it may be seen that it takes the place of all
of the brickwork that should be on that side. Had this been nothing
more than a very narrow water-cooled frame, with brickwork below
and supporting bricks above, put in like the tuyeres in a foundry
cupola, the case would have been somewhat different, for then it
would have absorbed a smaller proportion of the heat.

A blacksmith who knows how a piec