'J.4A: SMITHSONIAN CONTKIBUTIONS TO KNOWLEDGE VOL. 27 



having two of the mechanics turn the propellers. While this same plan might 

 have been followed in the case of the large aerodrome, yet it would have in- 

 volved some danger to the mechanics and would also have left the aviator with- 

 out any means of restarting the engine should it for any reason stop while in 

 l in air. Believing it to he very important to provide means for enabling the 

 aviator to restart the engine in case it stopped in the air, the writer devised 

 the starting mechanism shown in the drawings, Plates 78 to 80. Fastened by 

 tongues and grooves to the port side of the engine crank shaft, just outside of 

 the bed jdate, is a worm wheel, on the hub of which is mounted the bevel gear 

 which drives the water-circulation pump through the bevel pinion, as already 

 described. Moulded on the web of the bed plate are two brackets, in which 

 the shaft for the starting crank is journaled, this shaft passing forward and 

 downward through the front of the cross-frame of the aerodrome, where it is 

 journaled in a bracket secured to the brace tubes thereof. At the front or lower 

 end of the shaft a crank handle is connected thereto by a ratchet mechanism. 

 The upper end of the starting shaft, between the bearings of the two support- 

 ting brackets, is tongued and grooved, and slidably mounted thereon witli co- 

 acting grooves and tongues is a worm screw which, in the position shown in 

 Plates 79 and 80, is in gear with the worm wheel just described. However, 

 when the worm screw is slid along on the shaft until it is against the upper 

 bracket it is out of gear with the worm wheel. Mounted in the interior of the 

 tubular starting shaft is a spring-pressed pawl plug, not shown, but which pro- 

 jects through one of the tongues on the shaft near the upper bracket, [f the 

 worm screw is slid up against this upper bracket, this pawl catches in a radial 

 hole in the worm screw and holds it in this position old of gear with the worm 

 wheel. Connected to this pawl plug and passing longitudinally through the cen- 

 ter of the shaft is a wire which terminates in a button just at the end thereof. 

 By pulling on this button the operator may release the worm and thus permit 

 it to slide downward so that when the starting crank is turned in a clockwise 

 direction the worm will screw itself into gear with the worm wheel, and any 

 further turning of the starting crank will cause the worm to force the worm 

 wheel, and, consequently, the engine shaft, around in a clockwise direction. As 

 soon as the engine gets an explosion the worm wheel slides the worm along 

 against the upper bracket, where the spring pawl catches and holds it till it 

 is again released by the operator as before. 



This starting mechanism was a success from the first, and the engine was 

 never started up in any other way. With an aerodrome having the qualities of 

 automatic equilibrium, which the Langley machines have, it was felt very cer- 

 tain that by this mechanism the engine could be easily restarted while in the 

 air, in case it was inadvertently stopped. 



