ng acids, alkalies,
salts, reagents, every conceivable essential oil and all the thinkable
extracts. It may be remarked that this collection includes the eighteen
hundred or more fluorescent salts made by Edison during his experimental
search for the best material for a fluoroscope in the initial X-ray
period. All known metals in form of sheet, rod and tube, and of great
variety in thickness, are here found also, together with a most complete
assortment of tools and accessories for machine shop and laboratory
work.

The list is confined to the merest general mention of the scope of this
remarkable and interesting collection, as specific details would
stretch out into a catalogue of no small proportions. When it is stated,
however, that a stock clerk is kept exceedingly busy all day answering
the numerous and various demands upon him, the reader will appreciate
that this comprehensive assortment is not merely a fad of Edison's,
but stands rather as a substantial tribute to his wide-angled view of
possible requirements as his various investigations take him far afield.
It has no counterpart in the world!

Beyond the stock-room, and occupying about half the building on the same
floor, lie a machine shop, engine-room, and boiler-room. This machine
shop is well equipped, and in it is constantly employed a large force
of mechanics whose time is occupied in constructing the heavier class of
models and mechanical devices called for by the varied experiments and
inventions always going on.

Immediately above, on the second floor, is found another machine shop in
which is maintained a corps of expert mechanics who are called upon to
do work of greater precision and fineness, in the construction of tools
and experimental models. This is the realm presided over lovingly by
John F. Ott, who has been Edison's designer of mechanical devices for
over forty years. He still continues to ply his craft with unabated
skill and oversees the work of the mechanics as his productions are
wrought into concrete shape.

In one of the many experimental-rooms lining the sides of the second
floor may usually be seen his younger brother, Fred Ott, whose skill as
a dexterous manipulator and ingenious mechanic has found ample scope
for exercise during the thirty-two years of his service with Edison, not
only at the regular laboratories, but also at that connected with the
inventor's winter home in Florida. Still another of the Ott family, the
son o