, he pursued his
investigations with the thorough minuteness that characterizes all his
laboratory work, and in due time produced a mixture which on elaborate
test overcame all objections and answered the complex requirements
perfectly, including the making of a surface smooth, even, and entirely
waterproof. All the other engineering problems have received study in
like manner, and have been overcome, until at the present writing the
whole question is practically solved and has been reduced to actual
practice. The Edison poured or cast cement house may be reckoned as a
reality.

The general scheme, briefly outlined, is to prepare a model and plans of
the house to be cast, and then to design a set of molds in sections of
convenient size. When all is ready, these molds, which are of cast iron
with smooth interior surfaces, are taken to the place where the house
is to be erected. Here there has been provided a solid concrete cellar
floor, technically called "footing." The molds are then locked together
so that they rest on this footing. Hundreds of pieces are necessary for
the complete set. When they have been completely assembled, there will
be a hollow space in the interior, representing the shape of the house.
Reinforcing rods are also placed in the molds, to be left behind in the
finished house.

Next comes the pouring of the concrete mixture into this form. Large
mechanical mixers are used, and, as it is made, the mixture is dumped
into tanks, from which it is conveyed to a distributing tank on the top,
or roof, of the form. From this tank a large number of open troughs or
pipes lead the mixture to various openings in the roof, whence it flows
down and fills all parts of the mold from the footing in the basement
until it overflows at the tip of the roof.

The pouring of the entire house is accomplished in about six hours,
and then the molds are left undisturbed for six days, in order that the
concrete may set and harden. After that time the work of taking away
the molds is begun. This requires three or four days. When the molds are
taken away an entire house is disclosed, cast in one piece, from cellar
to tip of roof, complete with floors, interior walls, stairways, bath
and laundry tubs, electric-wire conduits, gas, water, and heating pipes.
No plaster is used anywhere; but the exterior and interior walls
are smooth and may be painted or tinted, if desired. All that is
now necessary is to put in the windows, doors