Nos. 13 and 14 COMPRESSED-AIR FLYING-MACHINES. 55 



There are two errors in the Proceedings for 1889, on page 71, 

 line 14, 128 should be 81 : and on page 74, line 38 for "miles per 

 hour," read " feet per second " and correct accordingly. 



No. 14 engine and machine, which is shown in Plates vi., vii., 

 viii, ix., is also driven by compressed-air; and the re-distribution of 

 the various parts, with the increased skill in construction acquired 

 by practice are thought to have resulted in a apparatus that, for 

 its weight, will be hard to excel. 



The receiver is two inches in diameter and six feet eleven inches 

 in length, and the working pressure 250 lbs. per square inch. The 

 area of floating surface is 3290 square inches, 3074 square inches 

 of which are in the body plane, and 22*27 % of the total area is in 

 advance of the centre of gravity. A vibrating enuriue stands on 

 the top of the receiver, thirteen inches from the forward end. The 

 cylinder is two inches diameter and 1"28 inches stroke. The wings 

 are of the usual size and shape. The cross-head pin that works 

 the valve also actuates the counter. The total weight of the 

 charged apparatus is fifty -nine ounces. 



No. 14 flew three hundred and twelve feet in nineteen seconds, 

 making forty-six double vibrations at 57Ibs.per square inch reduced 

 pressure ; and, supposing the efficiency to be *29, the foot-pounds 

 of work in the flight were five hundred and nine. 



The flight was above the level of the eye, until the engine stopped 

 from some cause at present unexplainable. It fell to the ground 

 almost vertically. Not the slightest damage was done, the break- 

 ing-stick was not even broken, and the machine w i ked perfectly 

 when taken back to the shop. No. 14 makes ninety double 

 rib rations before the pressure falls to 501bs., so that i wo hundred 

 yards is not too much to expect it to fly. 



The first trial of No. 14 was a failure, owing it was thought, 

 to the wing arms being too stiff. On taking off one of the wings 

 and holding it firmly by the butt, it was found that |lb. hung two 

 feet two and a half inches from the fulcrum and seven inches abaft 

 the wing arm twisted it 6°. Both wings were therefore thinned 

 until the Jib. weight twisted the wing tips 8°. 



