Mason made his first mark on the chess scene in 1876 when he won the Fourth American Chess Congress in Philadelphia, the New York Clipper tournament, and defeated Henry Bird in a match by the comfortable margin of 13–6. In 1878 he settled in England. His best tournament results were third at the Vienna 1882 tournament, third at Nuremberg 1883 and equal second at Hamburg 1885. At Hastings 1895, often considered the strongest tournament of the nineteenth century, he finished tied for 12th–14th with 9½ points of 21 possible.