f John F., for some years past has been on the experimental staff
of the Orange laboratory. Although possessing in no small degree the
mechanical and manipulative skill of the family, he has chosen chemistry
as his special domain, and may be found with the other chemists in one
of the chemical-rooms.

On this same floor is the vacuum-pump room with a glass-blowers' room
adjoining, both of them historic by reason of the strenuous work done
on incandescent lamps and X-ray tubes within their walls. The tools and
appliances are kept intact, for Edison calls occasionally for their use
in some of his later experiments, and there is a suspicion among the
laboratory staff that some day he may resume work on incandescent lamps.
Adjacent to these rooms are several others devoted to physical and
mechanical experiments, together with a draughting-room.

Last to be mentioned, but the first in order as one leaves the head of
the stairs leading up to this floor, is No. 12, Edison's favorite room,
where he will frequently be found. Plain of aspect, being merely a space
boarded off with tongued-and-grooved planks--as all the other rooms
are--without ornament or floor covering, and containing only a few
articles of cheap furniture, this room seems to exercise a nameless
charm for him. The door is always open, and often he can be seen seated
at a plain table in the centre of the room, deeply intent on some of the
numerous problems in which he is interested. The table is usually pretty
well filled with specimens or data of experimental results which have
been put there for his examination. At the time of this writing these
specimens consist largely of sections of positive elements of the
storage battery, together with many samples of nickel hydrate, to which
Edison devotes deep study. Close at hand is a microscope which is
in frequent use by him in these investigations. Around the room, on
shelves, are hundreds of bottles each containing a small quantity
of nickel hydrate made in as many different ways, each labelled
correspondingly. Always at hand will be found one or two of the
laboratory note-books, with frequent entries or comments in the
handwriting which once seen is never forgotten.

No. 12 is at times a chemical, a physical, or a mechanical
room--occasionally a combination of all, while sometimes it might be
called a consultation-room or clinic--for often Edison may be seen there
in animated conference with a group of his assista