pread over this space
there passes, automatically, in course of treatment, a vast quantity
of material resulting in the production of upward of two and a quarter
million pounds of finished cement every twenty-four hours, seven days in
the week.

In that one day's designing provision was made not only for all
important parts, but minor details, such, for instance, as the carrying
of all steam, water, and air pipes, and electrical conductors in a large
subway running from one end of the plant to the other; and, an oiling
system for the entire works. This latter deserves special mention, not
only because of its arrangement for thorough lubrication, but also on
account of the resultant economy affecting the cost of manufacture.

Edison has strong convictions on the liberal use of lubricants, but
argued that in the ordinary oiling of machinery there is great waste,
while much dirt is conveyed into the bearings. He therefore planned
a system by which the ten thousand bearings in the plant are oiled
automatically; requiring the services of only two men for the entire
work. This is accomplished by a central pumping and filtering plant
and the return of the oil from all parts of the works by gravity. Every
bearing is made dust-proof, and is provided with two interior pipes. One
is above and the other below the bearing. The oil flows in through the
upper pipe, and, after lubricating the shaft, flows out through the
lower pipe back to the pumping station, where any dirt is filtered out
and the oil returned to circulation. While this system of oiling is
not unique, it was the first instance of its adaptation on so large and
complete a scale, and illustrates the far-sightedness of his plans.

In connection with the adoption of this lubricating system there
occurred another instance of his knowledge of materials and intuitive
insight into the nature of things. He thought that too frequent
circulation of a comparatively small quantity of oil would, to some
extent, impair its lubricating qualities, and requested his assistants
to verify this opinion by consultation with competent authorities. On
making inquiry of the engineers of the Standard Oil Company, his theory
was fully sustained. Hence, provision was made for carrying a large
stock of oil, and for giving a certain period of rest to that already
used.

A keen appreciation of ultimate success in the production of a fine
quality of cement led Edison to provide very carefully in