In examining the system, it is difficult to determine what single element in its design might have caused such a problem as to have been beyond the engineering ability of a French firm, and to have caused such concern to a large, well-established American organization of Otis' wide elevator and inclined railway experience. Indeed, when the French system--which served the first platform from the east and west legs--is examined, it appears curious that a national technology capable of producing a machine at such a level of complexity should have been unable to deal easily with the entire matter. This can be plausibly explained only on the basis of Europe's previously mentioned lack of experience with rope-geared and other cable-hung elevator systems. The difficulty attending Otis' work, usually true in the case of all innovations, lay unquestionably in the multitudes of details--many of them, of course, invisible when only the successfully working end product is observed. More than a matter of detail was the Commission's demand for perfect safety, which precipitated a situation typical of many confronting Otis during the entire work. Otis had wished to coordinate the entire design process through Mr. Hall, with technical matters handled by mail. Nevertheless, at Eiffel's insistence, and with some inconvenience, in 1888 the company dispatched the project's engineer, Thomas E. Brown, Jr., to Paris for a direct consultation. Mild conflict over minor details ensued, but a gross difference of opinion arose ultimately between the American and French engineers over the safety of the system. The disagreement threatened to halt the entire project. In common with all elevators in which the car hangs by cables, the prime consideration here was a means of arresting the cabin should the cables fail. As originally presented to Eiffel, the plans indicated an elaborate modification of the standard Otis safety device--itself a direct derivative of E. G. Otis' original. If any one of the six hoisting cables broke or stretched unduly, or if their tension slackened for any reason, powerful leaf springs were released causing brake shoes to grip the rails. The essential feature of the design was the car's arrest by friction between its grippers and the rails so that the stopping action was gradual, not sudden as in the elevator safety. During proof trials of the safety, made prior to the fair's opening by cutting away a set of temporary hoisting cables, the cabin would fall about 10 feet before being halted. [Illustration: Figure 26.--Section through the Otis power cylinder. (Adapted from Gustave Eiffel, _La Tour de Trois Cents Mètres_, Paris, 1900, pl. 22.)] [Illustration: Figure 27.--Details of the counterweight carriage in the Otis system. (From Gustave Eiffel, _La Tour de Trois Cents Mètres_, Paris, 1900, pl. 22{4}.)]