. A sketch of the origin and progress of steam navigation from authentic documents. xtremitiesof the spokes or radii of the wheel which turns on the shaft which isworked by the engine ; the centre of this wheel being at O, So farthis wheel is similar to the common paddle-wheel; but the paddle-boards are not, as in the common wheel, fixed at A, B, C, &c,, so as to July 2. 1829, 106 STEAM NAVIGATION. be always directed to the centre O, but are so placed that they arecapable of turning on axles which are always horizontal, so that theycan take any angle with respect to the water which may be give
. A sketch of the origin and progress of steam navigation from authentic documents. xtremitiesof the spokes or radii of the wheel which turns on the shaft which isworked by the engine ; the centre of this wheel being at O, So farthis wheel is similar to the common paddle-wheel; but the paddle-boards are not, as in the common wheel, fixed at A, B, C, &c,, so as to July 2. 1829, 106 STEAM NAVIGATION. be always directed to the centre O, but are so placed that they arecapable of turning on axles which are always horizontal, so that theycan take any angle with respect to the water which may be given tothem. From the centres, or the line joining the pivots on which thesepaddle-boards turn, there proceed short arms K, firmly fixed to thepaddle-boards at an angle of about 120°. On a motion given to thisarm K, it will therefore give a corresponding angular motion to thepaddle-board, so as to make it turn on its pivots. At the extremitiesof the several arms marked K is a pin or pivot, to which the extre-mities of the radial arms L are severally attached, so that the angle. between each radial arm L and the short paddle-arm K is capable ofbeing changed by any motion imparted to L: the radial arms areconnected at the other end with a centre, round which they are ca-pable of revolving. STEAM NAVIGATION. 107 « Now, since the points A, B, C, &c., which are the pivots on the paddle-boards turn, are moved in the circumference of acircle, of which the centre is O, they are always at the same distancefrom that point; consequently they will continually vary their dis-tance from the other centre P. Thus, when a paddle-board arrivesat that point of its revolution at which the centre round which it re-volves lies precisely between it and the centre O, its distance fromthe former centre is less than in any other position. As it departsfrom that point, its distance from that centre gradually increasesuntil it arrives at the opposite point of its revolution, where the centreO is
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Keywords: ., bookcentury1800, bookdecade1840, bookidcu3192403090, bookyear1848
