Returning to Germany, he became a pupil in the engine works of Count Stolberg, to study mechanical engineering. While there he worked out a great improvement upon Watt’s centrifugal governor for regulating the supply of steam to an engine, and in 1844 he returned to England with his invention, and soon decided to stay here. His object in doing so was to enjoy the security which the English patent law afforded to inventors, for in his own country there were then no such laws. This chronometric governor, though not very successful commercially, introduced him to the engineering world; it was originally intended for steam engines, but its chief application has been to regulate the movement of the great transit instrument at Greenwich. Then followed in quick succession several minor inventions which met with varying practical success, such as the process of anastatic printing, which was made the subject of a Royal Institution lecture in 1845 by Faraday; a water meter, which has since been in general use; an air pump, &c., &c. About this time the researches of Joule, Carnot, and Mayer upon the relations between heat and mechanical work were attracting much attention among scientific men, and at the age of twenty-three, William Siemens adopted the hypothesis now known as the dynamical theory of heat. More than once I have drawn attention to the exact numerical relation between units of heat and units of work established by Joule, viz., that 772 foot-pounds of work is required to generate heat enough to raise the temperature of 1 lb. of water 1° Fah., and I have pointed out here and elsewhere that this was the first well-authenticated example of that grandest of modern generalisations, the doctrine of the Conservation of Energy, the truth of which is constantly receiving new illustrations.