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POPULAR SCIENCE MONTHLY. 



the relative advantages of all known systems for propulsion and guid- 

 ance, and to attain practical experience in manipulating air craft. The 

 operator and machinery are suspended below a peculiarly shaped gas- 

 spindle, whose fabric has been treated by a special process, original 

 with me, which enables it to retain hydrogen permanently during use. 

 It has within a limited period made upwards of one hundred flights, 

 embracing New York State, Massachusetts, New Hampshire, Maine, 



Fig. I. Mekritt's Flying Machine. 



Fig. 



Liebrand's Flying Machine. 



Delaware, Connecticut, New Jersey, Pennsylvania, Maryland, Virginia, 

 Tennessee, Ohio, Michigan and Illinois. 



"Three machines only have been built, varying somewhat in form 

 of spindle and extent of surface handled. As used at present, the 

 screw, formerly fifteen feet diameter, has been reduced to eight feet, 

 and the wings and rudder abandoned, the universal-jointed aeroplanes 

 on each side haying proved in every way superior for all evolutions. 



