DESCRIPTION OF THE ENGINES ON BOARD THE IRON STEAM TUG, THE ""ALICE""
Minutes of the Proceedings of the Institution of Civil Engineers
54 with an inclined projection, depresses the gate as much the depth of the immersion of the boat, and as much water escapes as can pass between its sides and the walls of the contracted part of the basin. T h e same action takes place in ascending, except that a certain amount of power must be expended to enable the boat to surmoutlt the difference of level between the basins. The quantity of water wasted by each boat would be in proportion to its immersion and the speed at which it passed
... the gate. I n case of different sized boats passing along the same canal, it is proposed to have a small gate forming part of the main gate, so as to avoid the loss of water which would ensue from the whole width being open for the passage of a small boat. This system has only been tried by models; but it is proposed to make an essay on an extensive canal nest summer, when the results will be communicated to the Institution. May 5, 1840. " Description of the Engines on board the Iron Steam Tug, the Alice." By J. Patrick, Inst. C. E. 'I'heSteam T h e speed of this boat having far exceeded the constructor's esthe pectations, induced the authorto send a description of her proportions, and of the construction of the engines. The chicf peculiarity in the engines is their being placed in the centre of the vessel, with the two cylinders in a line with the keel, and placed at an angle of 45", inclining inwards towards the paddle shaft, to which the motion is communicated direct (without the use of side beams) by long connecting rods attached to the cross heads, which are placed at the lower ends of the cylinders, instead of being on the top as in the usual manner; the connecting rods are thus enabled to be three times instead of twice the length of the stroke, as is usually the case. The framing is entirely of wrought iron on the tension principle, and appears to resist the tendency to vibration better than cast-iron framing. For the two cylinders of 31 inches diameter, there is only one air pump of 22; inches diameter, with 194 inches length of stroke, instead of the usual complement of t w o air pumps, IS incllcs " Alice."