Complex sentence: Through the course of that winter, Curtiss was able to develop a float (pontoon) design that would enable him to take off and land on water and on 26 January, 1911, Curtis flew the first seaplane from the water in the United States.
Split into simpler sentences: Through the course of that winter, Curtiss was able to develop a float (pontoon) design that would enable him to take off and land on water. On January 26,1911, Curtis flew the first seaplane from the water in the United States.