NO. 3 LANGLEX MEMOIE ON MECHANICAL FLIGHT L63 



distance between the marks which the magnel would cause the pen to make when 

 its circuit was closed by the brush on the car passing across the contact strips 

 on the track would give correct measures of the time consumed by the car in 

 passing over each twelve inches of its travel. Upon test, however, it was round 

 impossible to get the chronograph magnets to work rapidly enough to respond 

 to the very rapid opening and closing of the circuit after the car had passed 

 over the first one-quarter of its length of travel. As a large part of the slowness 

 of action seemed to be due to the weight of the fountain pens, they were re- 

 placed by small glass tubes drawn out to a fine point and containing a small 

 amount of ink. These seemed, however, to be still too heavy to respond to the 

 rapid closing of the circuit unless the contacts were made unduly long. The 

 contacts were finally made three inches long and placed only every three feet 

 along the track, but just as these contacts were completed and placed in posi- 

 tion the clock-work of the chronograph itself became deranged. Before it could 

 be repaired, the tests were discontinued, as everything was in readiness for the 

 boat to proceed down the river where the actual tests in free flight were to be 

 made. Tests of the final speed of the car were, however, made by the tuning- 

 fork method, and the springs were adjusted until their tension was sufficient 

 to cause the car to attain a speed of thirty-five feet a second at a point three 

 inches in front of the point at which the aerodrome would be released from the 

 car. 



