So far all was well, the heavy clouds that had so long hovered menacingly over Boulton and Watt had been displaced once more by clear skies. But no new machinery or new manufacturing business starts without accidents, delays and unexpected difficulties. There was necessarily a long period of trial and disappointment for which the sanguine partners were not prepared. As before, the chief trouble lay in the lack of skilled workmen, for although the few original men in Soho were remarkably efficient, the increased demand for engines had compelled the employment of many new hands, and the work they could perform was sadly defective. Till this time, it is to be remembered there had been neither slide lathes, planing machines, boring tools, nor any of the many other devices which now ensure accuracy. All depended upon the mechanics' eye and hand, if mechanics they could be called. Most of the new hands were inexpert and much given to drink. Specialisation had to be resorted to--one thing for each workman, in the fashioning of which practice made perfect. This system was introduced with success, but the training of the men took time. Meanwhile work already turned out and that in progress was not up to standard, and this caused infinite trouble. One very important engine was "The Bow" for London, which was shipped in September. The best of the experts, Joseph Harrison, was sent to superintend its erection. Verbal instructions Watt would not depend upon; Harrison was supplied in writing with detailed particulars covering every possible contingency. Constant communication between them was kept up by letter, for the engine did not work satisfactorily, and finally Watt himself proceeded to London in November and succeeded in overcoming the defects. Harrison's anxieties disabled him, and Boulton wrote to Dr. Fordyce, a celebrated doctor of that day, telling him to take good care of Harrison, "let the expense be what it will." Watt writes Boulton that Harrison must not leave London, as "a relapse of the engine would ruin our reputation here and elsewhere." The Bow engine had a relapse, however, which happened in this way. Smeaton, then the greatest of the engineers, requested Boulton's London agent to take him to see the new engine. He carefully examined it, called it a "very pretty engine," but thought it too complicated a piece of machinery for practical use. There was apparently much to be said for this opinion, for we clearly see that Watt was far in advance of his day in mechanical requirements. Hence his serious difficulties in the construction of the complex engine, and in finding men capable of doing the delicately accurate work which was absolutely indispensable for successful working.