An unusual torpedo boat (length 86 feet, beam 11 feet; depth 5 feet 6 inches) buiolt without funnels and having two balanced rudders one placed fore and the other aft, fitted with a 12.5 inch by 22 inch by 12 inch stroke compound engine operating at 520 revolutions per minute on steam supplied at 80 pounds per square inch by an experimental water-tube boiler built by Yarrow and Company for an unnamed foreign Government.