yachts and, incidentally, will enrich himself. That this problem will be solved eventually there is little doubt. I hope that Mr. Watson will live to see his prophecy realized, even to the extent of aerial navigation.
At present, however, the heavy first cost of aluminum and its short life, when exposed to the erosive action of sea water, bar its use in the construction of racing yachts, except when the sentiment of defending or regaining an historic national trophy is indulged in by a syndicate of capitalists. Probably no single millionaire would have gone to the expense of the Defender, but when the price of her was divided up among several, the plethoric purses were not so very much depleted after all.
Aluminum as a material for yachts has been an interesting subject to me ever since it was first used in shipbuilding. The aluminum used in the Defender had an alloy of from 12 to 15 per cent. of nickel. The majority of the plates used were 5/16 and 3/8 of an inch in thickness. The heaviest plate weighed about 200 pounds, was 38-1/2 inches wide, 13 feet 10 inches long, and 5/16 of an inch thick. This plate gave an ultimate tensile strength of 40,780 pounds per square inch, an elongation of 10 per cent. in 2 inches, and the reduction of area at the point of fracture was 14.75 per cent. Each and every plate used was tested.
The Defender was constructed of aluminum plating from the water-line
