Acting upon the Committee’s representation, the Central Railway Company ordered two new types of locomotives, in one of which the “unspring-borne” load was much reduced by gearing. The other was not distinct from but attached to the train, the motors being carried at one end of two or more coaches--the motor-car system of electric traction in fact. The difference in weight was remarkable; the original gearless engines being 44 tons, the new geared pattern 33 tons, while the motor-cars only came up to 20 tons. Some novel experiments were made, and in order to identify the trains, the houses in which the observers took their places with recording instruments were connected by telephone with the signal-boxes at the adjoining stations. Quite satisfactory were the results, and it was found that, during some two hours, the passing of every train drawn by the heavy gearless locomotive was distinctly felt, but was not discernible when the new engines were attached. Therefore the Committee concluded that, so far as the Central was concerned, the adoption of motor-cars would so reduce the _tremblement de terre_ as to cause all real annoyance to cease, though the sound of the trains, particularly at night, might still be detected. As to the oscillation of the cars--a rather marked feature in the Tube--it was attributed by the Committee’s experts to the unevenness of the surface of the rails. As these leave the rolling-mills they are usually slightly curved, and the process of straightening them _in situ_, however skilfully carried out, inevitably leaves a certain amount of waviness. When the speed is high, a condition of things soon arises whereby the irregular impulses produced by the uneven rail surfaces establishes a rocking movement of the rails and the road-bed, converting both into an elastic instead of a rigid support. This is increased and maintained by the pounding of the gearless locomotives in the narrow tubes, intensified by the hard unyielding material of which they are composed. Another fact to which the Committee called attention was, that in consequence of the small diameter of the tunnels (12 feet), the fit was too close, and the pressure in front of the trains necessitated greater power to overcome it than if more space had been left between the roofs of the carriages and the tubes. In the agitation respecting damage alleged to have been done by the construction of the Tubes, it was proved that provided the apertures are made of sufficient size, and suitable locomotives used, and the permanent way properly laid with stiffer and deeper rails, the chance of injury to houses by the _moviéndo la tiérra_, as the Spaniards call it, can be reduced to a minimum.