POPULAR SCIENCE REYIEW. 
369 
The experiment of the great lifting power of superposed 
planes has been tested repeatedly, by stringing a number of 
paper toy kites one above the other — the string then assumes a 
less inclined position ; the total weight is small. They are, of 
course, strong enough , and, if in sufficient numbers, will readily 
lift a man ; but, in a rough arrangement of this description, 
the conditions of resistance are too great to enable him to 
propel himself, when raised from the ground, with a force equal 
to the pull of the string, which, if very long, in itself exposes a 
large area to the wind. 
The bodies of all swift flyers are formed of such a figure as to 
cause but little impediment against the air in the line of mo- 
tion, and the greatest possible amount to vertical descent. 
These conditions would have to be considered in all artificial 
flying arrangements by disposing the material in a position 
that will offer the least forward resistance, like in the flight of an 
arrow, with all the front edges of the various parts made conical 
or wedge-shaped. 
B B 
VOL. XIII. 
-NO. LIII. 
