To English trade the canal opened up the richest of all markets, the market of England itself. Every part of the country was practically thrown open to the manufacturer; and the impulse which was given by this facility of carriage was at once felt in a vast development of production. But such a development would have been impossible had not the discovery of this new mode of distribution been accompanied by the discovery of a new productive force. In the coal which lay beneath her soil England possessed a store of force which had hitherto remained almost useless. Not the least were the new methods of smelting iron with coal instead of wood, which changed the whole aspect of the iron trade and which made Great Britain for many years the workshop of the world. Lead, copper, and tin were also mined and smelted by the use of coal. The great advance of the “industrial revolution” did not come until Watt’s improvements upon the steam engines of Newcomen, Cawley, and Savery, which were themselves improvements over earlier inventions of Papin, della Porta, and Worcester, made practicable the transfer of energy stored up in coal to the movement of machinery. He changed the steam engine from a clumsy, wasteful, inefficient machine into a workable apparatus little differing from the reciprocating steam engines of the present. Up until the successful operation of the turbine engine, the principal advances upon Watt’s engine were mere details, though often of great importance. For instance the boilers for the generation of steam were improved; the enlarged application of the principle of expansion, developing better cut-off mechanisms and governors, to more economical construction due to better facilities and better knowledge of materials and their properties; and to the application of the steam engine in locomotives to propel transportation cars. Watt’s claims and specifications for patents from 1769 to 1784 cover such inventions as: 1. Methods of keeping the cylinder or steam vessel hot by covering it with wood or other slow heat-conducting materials, by surrounding it with steam or other heated bodies, and by suffering no water or other substance colder than steam to touch it. 2. By condensing the steam in vessels entirely distinct from the cylinder, called condensers, which are to be kept cool. 3. By drawing out of the condenser all uncondensed vapors or gases by means of an air pump. 4. The use of the expansion force of steam directly against the cylinder. 5. The double-acting engine and the conversion of the reciprocating motion into a circular motion.[8] 6. Throttle valve with governor and gear for operating the same, parallel motion for opening and closing the valves, and indicator. These inventions not only made it possible to replace hand-labor often with machines, but made it possible to construct machines much more rapidly and to make them in every way more convenient.