Although the first five years of his American experience had been less profitable, in a pecuniary sense, than he had anticipated, he continued to reside in the city of New York, where he found an ample field for the exercise of his great powers in the line of his profession. He planned the war-steamer Pomone, the first screw-vessel introduced into the French navy. He planned revenue-cutters for the United States Government, taking care always to have his contracts so distinctly made that no question could again arise as to his "legal claim." He invented a useful apparatus for supplying the boilers of sea-going steamers with fresh water. He invented various modifications of the steam-engine. In the American division of the London Industrial Exhibition of all Nations in 1851, he exhibited the Distance-Instrument, for measuring distances at sea,--the Hydrostatic Gauge, for measuring the volume of fluids under pressure,--the Reciprocating Fluid-Metre, for measuring the quantity of water which passes through pipes during definite periods,--the Alarm-Barometer,--the Pyrometer, intended as a standard measure of temperature, from the freezing-point of water up to the melting-point of iron,--a Rotary Fluid-Metre, the principle of which is the measurement of fluids by the velocity with which they pass through apertures of different dimensions,--and a Sea-Lead, contrived for taking soundings at sea without rounding the vessel to the wind, and independently of the length of the lead-line. For these inventions he received the prize-medal of the Exhibition. But while thus continually occupied with new enterprises and objects, he did not lose sight of his great idea, the Caloric-Engine. All his spare hours and spare funds were devoted to experiments with the view of overcoming the practical difficulties which stood in the way of its success. Towards the end of the year 1851 he seemed to be on the point of realizing his hopes, having constructed a large stationary engine, which was applied with great success, at the Phoenix Foundry in New York, to the actual work of pumping water. Soon after, through the liberality of Mr. John B. Kitching, a well-known merchant of New York, he was enabled to test the invention on a magnificent scale. A ship of two thousand tons, propelled by the power of caloric-engines, was planned and constructed by him in the short space of seven months, and in honor of the inventor received the name of the "Ericsson."