t the various ramifications
of the plant, but the principal ones are worthy of mention, such as:

The giant rolls (for crushing).
Intermediate rolls.
Three-high rolls.
Giant cranes (215 feet long span).
Vertical dryer.
Belt conveyors.
Air separation.
Mechanical separation of phosphorus.
Briquetting.

That Mr. Edison's work was appreciated at the time is made evident
by the following extract from an article describing the Edison
plant, published in The Iron Age of October 28, 1897; in which, after
mentioning his struggle with adverse conditions, it says: "There is very
little that is showy, from the popular point of view, in the gigantic
work which Mr. Edison has done during these years, but to those who are
capable of grasping the difficulties encountered, Mr. Edison appears
in the new light of a brilliant constructing engineer grappling with
technical and commercial problems of the highest order. His genius as
an inventor is revealed in many details of the great concentrating
plant.... But to our mind, originality of the highest type as a
constructor and designer appears in the bold way in which he sweeps
aside accepted practice in this particular field and attains results not
hitherto approached. He pursues methods in ore-dressing at which
those who are trained in the usual practice may well stand aghast.
But considering the special features of the problems to be solved, his
methods will be accepted as those economically wise and expedient."

A cursory glance at these problems will reveal their import. Mountains
must be reduced to dust; all this dust must be handled in detail, so
to speak, and from it must be separated the fine particles of iron
constituting only one-fourth or one-fifth of its mass; and then this
iron-ore dust must be put into such shape that it could be
commercially shipped and used. One of the most interesting and striking
investigations made by Edison in this connection is worthy of note,
and may be related in his own words: "I felt certain that there must be
large bodies of magnetite in the East, which if crushed and concentrated
would satisfy the wants of the Eastern furnaces for steel-making.
Having determined to investigate the mountain regions of New Jersey, I
constructed a very sensitive magnetic needle, which would dip toward the
earth if brought over any considerable body of magnetic iron ore. One
of my laboratory assistants went out with