If any difficulty of a mechanical nature arose, people naturally turned to Watt for a solution. Thus the Glasgow University failed to get pipes for conveying water across the Clyde to stand, the channel of the river being covered with mud and shifty sand, full of inequalities, and subject to the pressure of a considerable body of water. Application was at last made to the recognised genius. If he could not solve it, who could? This was just one of the things that Watt liked to do. He promptly devised an articulated suction pipe with parts formed on the principle of a lobster's tail. This crustacean tube a thousand feet long solved the matter. Watt stated that his services were induced solely by a desire to be of use in procuring good water to the city of Glasgow, and to promote the prosperity of a company which had risked so much for the public good. These were handsomely acknowledged by the presentation to him of a valuable piece of plate. As another proof of Watt's habit of thinking of everything that could possibly be improved, it may be news to many readers that the consumption of the smoke from steam engines early attracted his attention, and that he patented devices for this. These have been substantially followed in the numerous attempts which have been made from time to time to reduce the huge volumes of smoke that keep so many cities under a cloud. He was successful and his son James writes to him in 1790 from Manchester: It is astonishing what an impression the smoke-consuming power of the engine has made upon everybody hereabouts. They scarcely trusted to the evidence of their senses. You would be diverted to hear the strange hypotheses which have been stated to account for it. This is all very well. It is certain that most of the smoke made in manufacturing concerns can be consumed, if manufacturers are compelled by law to erect sufficient heating surface and to include the well-known appliances, including those for careful firing, but no city so far as the writer knows has ever been able to enforce effective laws. There remain the dwellings of the people to deal with, which give forth smoke in large cities in the aggregate far exceeding that made by the manufacturing plants. New York pursues the only plan for ensuring the clearest skies of any large city in the world where coal is generally used, by making the use of bituminous coal unlawful. The enormous growth of present New York (45 per cent. in last decade) is not a little dependent upon the attraction of clear blue sides and the resulting cleanliness of all things in and about the city compared with others. When, by the progress of invention or new methods of distributing heat, smoke is banished, as it probably will be some day, many rich citizens will remain in their respective western cities instead of flocking to the clear blue-skied metropolis, as they are now so generally doing.