458 ANNUAL REPORT SMITHSONIAN INSTITUTION, 193 5 



them in agitated water, thus verifying the soundness of his 

 predictions. 



An Armstrong seadrome is a great platform constituting the 

 landing area for airplanes and supported by a certain number of 

 columns. 



There are two superposed decks: The upper one forms the land- 

 ing platform 475 meters long by 92 meters wide in the center and 

 46 meters wide at the ends. An elevator permits the airplane to 

 descend to the lower deck, where are found spacious hangars, re- 

 pair and maintenance shops, dwelling quarters for the crew, stores, 

 auxiliary equipment, as well as hotel accommodations for the pas- 

 sengers, a certain number of whom, one would think, would wish 

 to spend several days in the calmness and the pure air of the ocean, 

 only 8 hours from Paris, London, or New York. 



The upper deck, which is located 31 meters above the water, is 

 kept as clear as possible so that nothing may hamper the airplanes. 

 The lookout station and the antenna of the directional radio, in- 

 stalled completely above the deck, are the only protuberances. The 

 ensemble of the two decks forms a solidly braced metallic framework 

 which rests on 32 sheet-iron columns. Each of these is furnished 

 with a watertight reservoir, filled with air and forming a float, with 

 another reservoir at its lower end filed with iron ore serving as 

 ballast for the sake of its stability. It is in the judicious disposition 

 of these floats that resides the great superiority of the Armstrong 

 seadrome over all other known projects. It will, then, be desirable 

 to dwell a little on this point. The wave which you see shown in 

 the drawing (fig. 1) is 9 meters in height by 180 meters in length; 

 this is a degree of roughness greater than would be seen even dur- 

 ing a gale; as you see, not even the lower deck is reached by the 

 water. 



The amount of motion of the water produced by the waves de- 

 creases rapidly, however, below the surface. The floats, then, are 

 located in relatively calm water — like submerged submarines; the 

 result is that the supporting effort on the whole structure varies hardly 

 at all — so little that there is no pitching motion. There is produced 

 only a slight heaving, of the order of several centimeters. 



In actual use the lower ends of the columns are 63 meters below 

 the water level. In towing the seadrome to the place where it will 

 be used, this would be much too great. The columns are therefore 

 telescopic; during transportation the lower part is raised so that 

 they draw only 16 meters of water. 



In order to remain in the desired location, the seadrome is se- 

 cured first to a buoy, which in turn is fastened to an anchor of 

 special form. The maximum pull exerted by the water and by 



