Edison realized, however, that in commercial practice this was only a temporary expedient, and that a satisfactory permanence of results could only be attained with more perfect engines that could be depended upon for close and simple regulation. The engines that were made part of the first three "Jumbos" placed in the station were the very best that could be obtained at the time, and even then had been specially designed and built for the purpose. Once more quoting Edison on this subject: "About that time" (when he was trying to run several dynamos in parallel in the Pearl Street station) "I got hold of Gardiner C. Sims, and he undertook to build an engine to run at three hundred and fifty revolutions and give one hundred and seventy-five horse-power. He went back to Providence and set to work, and brought the engine back with him to the shop. It worked only a few minutes when it busted. That man sat around that shop and slept in it for three weeks, until he got his engine right and made it work the way he wanted it to. When he reached this period I gave orders for the engine-works to run night and day until we got enough engines, and when all was ready we started the engines. Then everything worked all right.... One of these engines that Sims built ran twenty-four hours a day, three hundred and sixty-five days in the year, for over a year before it stopped." [12] [Footnote 12: We quote the following interesting notes of Mr. Charles L. Clarke on the question of see-sawing, or "hunting," as it was afterward termed: "In the Holborn Viaduct station the difficulty of 'hunting' was not experienced. At the time the 'Jumbos' were first operated in multiple arc, April 8, 1882, one machine was driven by a Porter-Allen engine, and the other by an Armington & Sims engine, and both machines were on a solid foundation. At the station at Milan, Italy, the first 'Jumbos' operated in multiple arc were driven by Porter-Allen engines, and dash-pots were applied to the governors. These machines were also upon a solid foundation, and no trouble was experienced. "At the Pearl Street station, however, the machines were supported upon long iron floor-beams, and at the high speed of 350 revolutions per minute, considerable vertical vibration was given to the engines. And the writer is inclined to the opinion that this vibration, acting in the same direction as the action of gravitation, which was one of the two controlling forces in the operation of the Porter-Allen governor, was the primary cause of the 'hunting.' In the Armington & Sims engine the controlling forces in the operation of the governor were the centrifugal force of revolving weights, and the opposing force of compressed springs, and neither the action of gravitation nor the vertical vibrations of the engine could have any sensible effect upon the governor."]