NO. 3 LANGLBl MEMOIR ON MECHANICAL H.h.H! 263 



stored whenever il seemed probable thai a flight would soon be possible. Some 

 of the difficulties experienced in hoisting these wings from the interior of the 

 boat to the upper works may be appreciated by an inspection of Plate 94, where 

 one of them is seen just ready to be hoisted from the raft. Only one wing at 

 a time could be handled on the rait, even when there; was no appreciable wind 

 or roughness of the water, so that in order to hoist all four wings the raft hail 

 to be hauled around from the door at the end of the boat to the side where the 

 wing was hoisted, and hack again four times everj lime the machine was as- 

 sembled preparatory to a flight. The necessity for making occasional tests of 

 the engine in order to make sure that no trouble would be again experienced 

 in having proper batteries, etc., for the engine when the machine was again 

 on the point of being launched also made it imperative to remove the wings 

 from the interior of the house-boat, as the tremendous blasts of air from the 

 propellers would certainly have wrecked the wings had they remained in the 

 boat while the engine was being tested. 



After the wings had been stored in the " w T ing boxes," thorough tests of 

 the engine were made, and before there came another day which was at all 

 suitable for a trial, it was accidentally discovered that the glued joints in the 

 cross-ribs of the large wings had been softened by the moisture of the fogs 

 which had penetrated everything, and that the joints had all opened up and 

 left the ribs in a practically useless condition. 



It will be recalled from the description of these cross-ribs, Chapter VI, that 

 the rib is composed of two channel-shaped strips, the edges of which are glued 

 together while the strips are bent over a form which causes the ribs to main- 

 tain the curved form desired after the glue has hardened. Recalling these 

 facts, it will be readily understood that there is at all times a considerable strain 

 on the glued joints due to the two strips of wood trying to straighten out, and, 

 therefore, if the glue should at any time become softened sufficiently to allow 

 one strip to slide along on the other, the joint would open up and the rib would 

 consequently become straight. When the construction of the hollow ribs was 

 first contemplated it was realized that although the hollow construction would 

 enable the ribs to be strong, and at the same time exceedingly light, yet it 

 would make it imperative that the ribs be covered with a water-proof varnish 

 in order to prevent the glue from being softened when the aerodrome came down 

 into the water, as it was expected from the first that it would do at the end of 

 its flight. Considerable time and attention had, therefore, been given to this 

 very problem of securing a suitable water-proof varnish, and ribs coated with 

 the varnish which was finally used had been submerged in water for more than 

 24 hours in testing this very point, and no softening of the glue could be de- 

 tected after this long submergence. It had, therefore, been felt that the ribs 

 had been given a test "which was much more severe than any conditions which 



