Adaptation of the motor to the direct drive of an elevator machine was quite another matter, the difficulties being largely those of control. At this time the only practical means of starting a motor under load was by introducing resistance into the circuit and cutting it out in a series of steps as the speed picked up; precisely the method used to start traction motors. In the early attempts to couple the motor directly to the winding drum through worm gearing, this "notching up" was transmitted to the car as a jerking motion, disagreeable to passengers and hard on machinery. Furthermore, the controller contacts had a short life because of the arcing which resulted from heavy starting currents. In all, such systems were unsatisfactory and generally unreliable, and were held in disfavor by both elevator experts and owners. [Illustration: Figure 17.--Siemens' electric rack-climbing elevator of 1880. (From Werner von Siemens, _Gesammelte Abhandlungen und Vorträge_, Berlin, 1881, pl. 5.)] There was, moreover, little inducement to overcome the problem of control and other minor problems because of a more serious difficulty which had persisted since the days of steam. This was the matter of the drum and its attendant limitations. The motor's action being rotatory, the winding drum was the only practical way in which to apply its motive power to hoisting. This single fact shut electricity almost completely out of any large-scale elevator business until after the turn of the century. True, there was a certain amount of development, after about 1887, of the electric worm-drive drum machine for slow-speed, low-rise service (fig. 19). But the first installation of this type that was considered practically successful--in that it was in continuous use for a long period--was not made until 1889,[7] the year in which the Eiffel Tower was completed. Pertinent is the one nearly successful attempt which was made to approach the high-rise problem electrically. In 1888, Charles R. Pratt, an elevator engineer of Montclair, New Jersey, invented a machine based on the horizontal cylinder rope-geared hydraulic elevator, in which the two sets of sheaves were drawn apart by a screw and traveling nut. The screw was revolved directly by a Sprague motor, the system being known as the Sprague-Pratt. While a number of installations were made, the machine was subject to several serious mechanical faults and passed out of use around 1900. Generally, electricity as a practical workable power for elevators seemed to hold little promise in 1888.[8] [Illustration: Figure 18.--Motor and drive mechanism of Siemens' elevator. (From Alfred R. Urbanitzky, _Electricity in the Service of Man_, London, 1886, p. 646.)] [Illustration: _Morse, Williams & Co._, BUILDERS OF PASSENGER AND FREIGHT ELEVATORS. ELECTRIC ELEVATOR. Write us for Circulars and Prices. Main Office and Works, 1105 Frankford Avenue, PHILADELPHIA.