But, as was mentioned on a previous page, the steam engine at this date was not developed with a view to transport, but for the convenience of pumping up water from mines. As a result of Watt’s success a considerable demand arose among Cornish mine-owners for these engines made by Boulton and Watt, who were now working in partnership together. For the work of pumping, these machines continued to serve admirably, so long as a vertical up-and-down motion was required. At length Watt turned his mind to some method of obtaining rotary movement from his engine, but in a manner different from that in which Hulls had attempted to attain his end. Watt had covered in the top of his cylinder to keep out the cooling effect of the air, and his well-known beam pumping engine was an improvement on Newcomen’s, owing to the simple fact that in economising steam it halved the cost of fuel, and not even to-day are these old-fashioned engines in disuse. As we shall see later on, the beam engine is very much in evidence in some of the river steamships of the United States, apart altogether from those beam engines which are still worked for pumping in some parts of our own country. With such satisfactory results to encourage him it was inevitable that sooner or later so brilliant a schemer would think out some means for rotary movement, and Watt’s first intention was to cause the beam (which was pushed up by the rod joining the piston) to drive a fly-wheel by introducing a crank in something of the same manner in which nowadays the crank of a bicycle drives round the cog-wheel, the cyclist’s leg being, so to speak, the connecting rod which joins the beam. But before Watt had a chance of getting legal protection for this method his secret was stolen by one of his workmen, named Pickard, who revealed it to a Bristol man of the name of Wasbrough, who was also in search of some method of obtaining rotary motion. The latter, therefore, having in 1780 obtained his patent by stealth, Watt was compelled to cast about for some other means of attaining the same end: but his fertile mind soon gave forth what was required, and in the following year he patented what is known as the “sun-and-planet” gear, which converted the vertical movement into a rotary. Put in a few words, the working of the engine was as follows: At the top was the straight beam of wood; from one side of this there hung vertically a rod which connected with the piston in the cylinder, and was thus made to go up and down as in the Newcomen engine. It will be remembered that in Newcomen’s machine, at the opposite end of the beam was the other rod for pumping the water. Now in Watt’s rotary engine the piston-rod was moved up and down as before, but the opposite rod, at the other end of the beam, was connected with a spur-wheel having cogs in it. There was also a large fly-wheel which had a similar cog-wheel on its shaft, and thus, as the piston rod pushed up its end of the beam the