ABRONAUTICAL WORK. 43 
type of the supporting surfaces of flying machines. A single 
experiment will show anyone that absolute stability and certainty 
of action may be relied on ; and that the careful adjustment and 
balancing of single planes and affairs with a diedral angle is 
wasted labour. 
The earlier forms of cellular kites had the planes altogether 
edged with wood, and they needed much diagonal staying. Pin 
and eye joints would have been necessary at all the corners if they 
had been made to collapse, and want of space for storage began 
to be felt. The distance between the cells has been greatly 
reduced ; the exact distance that they can be apart without im- 
pairing the efficiency of the after cell is not known ; but, as far 
as stability is concerned, a single cell is in stable equilibrium. 
There is a single celled kite in the collection, measuring two feet 
six inches long, two feet six inches deep, and six feet wide, and 
it flies quite steadily. 
A number of experiments have been made with curved wooden 
cellular kites. Efforts have been made to induce them to soar to 
windward of the peg to which the string was fastened. Plate 6 
shows the nearest approach to soaring that has been attained. 
There is a wedge and screw that secures the forward cell at an 
angle with the stick and tail cell, so that various degrees of tilt 
may be tried. 
Plates 4 and 5 show a variety of stable forms of kites. Some 
&re probably new and may be useful to the readers of this Journal. 
‘ A great deal has appeared about Mr. Otto Lilienthal’s long 
Jumps from an eminence on an apparatus weighing about forty- 
four pounds, and spreading one hundred and fifty square feet of 
Wing surface. The weight seems very high for a structure intended 
for aeronautical purposes, but doubtless it is skilfully designed and 
the material found to be requisite. The writer put together and 
made several jumps with a trussed affair having four wings eight 
feet by four feet nine inches, equal to a total area of one hundred 
8nd fifty-two square feet of arched surface; it weighed under 
