L. MECHANICS AND ENGINEERING. 503 



under these heads, he says that the first helicopter was that 

 of Launoy and Bienverin in 1784. The instruments of this 

 class invented by himself, and finally brought to perfection 

 in 1871, would, when started in a horizontal position, at first 

 descend slowly, then, with the velocity thus acquired, would 

 rise, and describe a regular path at seven or eight feet above 

 the ground, over a course of one hundred and fifty feet, en- 

 durino- about eleven seconds. Some models have even main- 

 tained themselves thirteen seconds in the air, and described 

 a path of two hundred feet, being as free as birds from all 

 communication with the ground during their flight. The 

 construction of the mechanical bird presents far more seri- 

 ous difficulties than the construction of the helicopter or 

 the aeroplane. Marey, whose abundant researches on the 

 subject of flight, walking, running, etc., are well known, con- 

 structed artificial insects in 1870, which rose and turned by 

 means of their wings, but were assisted by compressed air 

 driven from a force-pump. The improvements that were 

 made in the following two years were remarked upon at 

 the meeting of the Society for Aerial Navigation, in June, 

 1872, when two pieces of apparatus were presented, the one 

 by Penaud, the other by Hureau de Villaneuve. A bird 

 constructed by the latter had a remarkable power of wing, 

 and at each stroke one could see the body rise. Unhappily 

 the strokes were too few, and, occurring only once for every 

 horizontal movement of one meter, it followed that the bird 

 slowly descended like a parachute. The bird constructed 

 by Penaud could not ascend vertically, but moved horizon- 

 tally with great rapidity, elevating itself, at the same time, 

 by means of a railing inclined at 15 or 20. These first 

 models were subsequently somewhat improved, so that an- 

 other bird constructed by Penaud took a long flight, in the 

 course of which it successivelv elevated and lowered itself 

 by a motion similar to that seen in the flight of many small 

 birds. The present state of the question is perhaps best de- 

 scribed by saying that, while we have models which show 

 that something is possible, yet the difficulties in the way of 

 passing from these up to such larger apparatus as is demand- 

 ed in order that mankind may avail themselves of this mode 

 of progression, are, at present, too difficult to be overcome. 

 The helicopters and the mechanical birds seem, in fact, en- 



