its earliest commercial form (1891),
with the motor connected directly to the load. By this time, incandescent
lighting circuits in large cities were sufficiently extensive to make such
installations practical. However, capacity and lift were severely limited
by weaknesses of the control system and the necessity of using a drum.
(From _Electrical World_, Jan. 2, 1897, vol. 20, p. xcvii.)]

[Illustration:

MILLER'S PATENT
LIFE AND LABOR-SAVING
SCREW HOISTING MACHINE,
FOR THE USE OF
Stores, Hotels, Warehouses, Factories, Sugar Refineries,
Packing Houses, Mills, Docks, Mines, &c.
MANUFACTURED BY
CAMPBELL, WHITTIER & CO., ROXBURY, MASS.
_Sole Agents for the New England States._

The above Engraving illustrates a very superior Hoisting Machine, designed
for _Store and Warehouse Hoisting_. It is very simple in its construction,
compact, durable, and not liable to get out of order. An examination of
the Engraving will convince any one who has any knowledge of Machinery,
that the screw is the only safe principle on which to construct a Hoisting
Machine or Elevator.

Figure 20.--Advertisement for the Miller screw-hoisting machine, about
1867 (see p. 23). From flyer in the United States National Museum.]

[Illustration: Figure 21.--The first widespread use of electricity in the
elevator field was to drive belt-type mechanical machines and the pumps of
hydraulic systems (see p. 14) as shown here. (From _Electrical World_,
Jan. 4, 1890, vol. 15, p. 4.)]

The Tower's Elevators

A great part of the Eiffel Tower's worth and its _raison d'etre_ lay in
the overwhelming visual power by which it was to symbolize to a world
audience the scientific, artistic, and, above all, the technical
achievements of the French Republic. Another consideration, in Eiffel's
opinion, was its great potential value as a scientific observatory. At its
summit grand experiments and observations would be possible in such fields
as meteorology and astronomy. In this respect it was welcomed as a
tremendous improvement over the balloon and steam winch that had been
featured in this service at the 1878 Paris exposition. Experiments were
also to be conducted on the electrical illumination of cities from great
heights. The great strategic value of the Tower as an observation post
also was recognized. But from the beginning, sight was never lost of the
structure's great value as an unprecedented public attraction, and its
syste