It afterwards appeared, however, that Sir William Symonds, then Surveyor to the Navy, had expressed the opinion that "even if the propeller had the power of propelling a vessel, it would be found altogether useless in practice, because the power being applied at the stern, it would be absolutely impossible to make the vessel steer!" It will be remembered that Francis Pettit Smith's screw vessel went to sea in the course of the same year; and not only faced the waves, but was made to steer in a perfectly successful manner.
Although the Lords of the Admiralty would not further encourage the screw propeller of Ericsson, an officer of the United States Navy, Capt.

R.F.Stockton, was so satisfied of its success, that after making a single trip in the experimental steamboat from London Bridge to Greenwich, he ordered the inventor to build for him forthwith two iron boats for the United States, with steam machinery and a propeller on the same plan.

One of these vessels--the Robert F.
Stockton--seventy feet in length, was constructed by Laird and Co., of Birkenhead, in 1838, and left England for America in April 1839.

Capt.
Stockton so fully persuaded Ericsson of his probable success in America, that the inventor at once abandoned his professional engagements in England, and set out for the United States.

It is unnecessary to mention the further important works of this great engineer.
We may, however, briefly mention that in 1844, Ericsson constructed for the United States Government the Princeton screw steamer--though he was never paid for his time, labour, and expenditure.[6] Undeterred by their ingratitude, Ericsson nevertheless constructed for the same government, when in the throes of civil war, the famous Monitor, the iron-clad cupola vessel, and was similarly rewarded! He afterwards invented the torpedo ship--the Destroyer--the use of which has fortunately not yet been required in sea warfare.