Watt hastened back to Birmingham, and after settling his wife in her new home, proceeded with the execution of the orders for engines which had come in during his two months’ absence. Mr. Wilby was impatient for the delivery of the Bow engine, and as soon as it was ready, which was early in September, the materials were forwarded to London with Joseph Harrison, to be fitted and set to work. Besides careful verbal instructions, Watt supplied Joseph with full particulars in writing of the measures he was to adopt in putting the engine together. Not a point in detail was neglected, and if any difficulty arose, Joseph was directed at once to communicate with him by letter. When the engine was set to work, it was found that the steam could not be kept up, on which Watt suggested that as it had been calculated to make only ten strokes per minute--that being enough to raise the quantity of water desired--the reason of the defect must be that, as it was going at fourteen or fifteen strokes the minute, it must be going too fast. He also pointed out that probably the piston was not quite good, and perhaps there was some steam-leak into the inner cylinder, or by the regulators into the condenser; or it was possible that the injection might spout too far up the horizontal steam-pipe and throw water into the inner nozzle. All these points Joseph must carefully look to. On further trials the engine improved; still its performances did not come up to Watt’s expectations, and there were consequently more directions from him as to the packing of the pistons and measures for the prevention of leaks. But to see that his suggestions were properly carried out, Watt himself went up to town in November, and had the machine put in complete working trim. His partner, however, could not spare him long, as other orders were coming in. “We have a positive order,” wrote Boulton, “for an engine for Tingtang mine, and, from what I heard this day from Mr. Glover, we may soon expect other orders from Cornwall. Our plot begins to thicken apace, and if Mr. Wilkinson don’t bustle a little, as well as ourselves, we shall not gather our harvest before sunset.” ... “I hope to hear,” he added, “that Joseph hath made a finish, for he is much wanted here.... I perceive we shall be hard pushed in engine-work; but I have no fears of being distanced when once the exact course or best track is determined on.”[152] Joseph Harrison got quite knocked up and ill through his anxiety about the Bow engine, on which Boulton wrote Watt to send at once for Dr. Fordyce to attend him, “let the expense be what it will, until you think him safe landed.”