Dr. A. E. Kennelly, now professor of electrical engineering
in Harvard University to whose energetic and capable management were
intrusted many scientific investigations during his long sojourn at
the laboratory. Unfortunately, however, for the continued success of
Edison's elaborate plans, he had not been many years established in the
laboratory before a trolley road through West Orange was projected and
built, the line passing in front of the plant and within seventy-five
feet of the galvanometer-room, thus making it practically impossible to
use it for the delicate purposes for which it was originally intended.

For some time past it has been used for photography and some special
experiments on motion pictures as well as for demonstrations connected
with physical research; but some reminders of its old-time glory still
remain in evidence. In lofty and capacious glass-enclosed cabinets, in
company with numerous models of Edison's inventions, repose many of
the costly and elaborate instruments rendered useless by the ubiquitous
trolley. Instruments are all about, on walls, tables, and shelves, the
photometer is covered up; induction coils of various capacities,
with other electrical paraphernalia, lie around, almost as if the
experimenter were absent for a few days but would soon return and resume
his work.

In numbering the group of buildings, the galvanometer-room is No. 1,
while the other single-story structures are numbered respectively 2, 3,
and 4. On passing out of No. 1 and proceeding to the succeeding building
is noticed, between the two, a garage of ample dimensions and a smaller
structure, at the door of which stands a concrete-mixer. In this small
building Edison has made some of his most important experiments in the
process of working out his plans for the poured house. It is in this
little place that there was developed the remarkable mixture which is to
play so vital a part in the successful construction of these everlasting
homes for living millions.

Drawing near to building No. 2, olfactory evidence presents itself of
the immediate vicinity of a chemical laboratory. This is confirmed as
one enters the door and finds that the entire building is devoted to
chemistry. Long rows of shelves and cabinets filled with chemicals line
the room; a profusion of retorts, alembics, filters, and other chemical
apparatus on numerous tables and stands, greet the eye, while a corps
of experimenters may be seen busy in