78 LAWRENCE HARGRAVE. 
moving at the end of an arm through still air are not under the 
same conditions as bodies flying in disturbed air, determined the 
selection of kites as the best means to the desired end. 
Plates 3 and 4, are some of the kites, and are sufficient to indi- 
cate the extent of the field now open for experiment. The novelty, 
if any, consists in the combination of two well known facts. 
First, that the necessary surface for supporting heavy weights 
may be composed of parallel strips superposed with an interval 
between them. (Described by Wenham in 1866 and adopted by 
Stringfellow in 1868. The writer made an experiment in 1889 
with superposed planes, but failed to show that any additional 
support was obtained. Prof. Langley showed by inference that 
there is an additional support, pages 33 and 47 of “ Experiments 
in /Hrodynamics,” 1891.) 
Second, that two planes separated by an interval in the direc- 
tion of motion are more stable than when conjoined. (Patented 
by Danjard in 1871, made and exhibited by D. 8. Brown in 1874.)* 
The form the complete kite assumes is like two pieces of honey- 
comb put on the ends of a stick, the stick being parallel to the 
axes of the cells. The cells may be of any section or number ; 
the rectangular cells are easiest to make, and, if the stick or strut 
between the two sets is placed centrally, as in kites B. ¢., it is 
immaterial which side is up. Practically, the top or bottom is 
~ determined by imperfections in the construction, This is of 
particular advantage for flying-machines driven by a single screw. 
The rectangular form of cell is also collapsible when one diagonal 
tie is disconnected. 
* In ‘*The American Engineer and Railroad Journal” Vol. uxvit., No. 
3, Mr. O. Chanute states, that, Mr. H. F. Phillips patented in 1890 an 
serial vehicle with superposed surfaces in two or more series, the surfaces 
might be fifteen feet long, six inches wide, and two inches apart; no 
mention being made of vertical surface which the writer finds essential 
to stability. Prof. Langley shows that the distance apart of the super- 
posed surfaces cannot, with advantage, be less than eighty-three per 
-cent. of the width of the planes. 
