442 



BELL 



Dimensions. — Each cell had a side of 25 centimeters, so 

 that the roof, or ridge pole, measured 6 meters extending later- 

 ally across the top of the structure. The oblique sides were 3 

 meters in length ; and the bottom, or floor, formed a square hav- 

 ing a side of 3 meters. The whole structure constituted a sec- 

 tion of a tetrahedral kite — the upper half in fact, of a kite, 

 having the form of a regular tetrahedron with a side of 6 meters. 

 Weight. — The winged cells composing this structure weighed 

 on the average 13.84 gms. apiece, so that the whole cellular 

 part of the structure which supported all the rest — consisting 

 of 1,300 winged-cells — weighed 17,992 gms. 



In addition to this, the kite carried as dead load stout sticks 

 of wood which were run through the structure to distribute the 

 strain of the pull upon the strong parts of the framework — 

 that is, upon the junction points of the cells. The outside edge 

 of the kite was also protected by a beading of wood. The whole 

 strengthening material weighed 9,702 gms., and the kite, as a 

 whole, weighed 27,694 gms. (61 lbs.). 



Surface. — I estimate the surface of an equilateral triangle 

 having a side of 25 centimeters, as about 270.75 square centi- 

 meters. In which case the silk surface of a single winged-cell, 

 consisting of two triangles, amounts to 541.5 square centime- 

 ters ; and the actual silk surface employed in 1,300 cells equals 

 70.3950 square meters (757-7 sq. ft.). 



The surfaces are all oblique ; and if we resolve the oblique 

 surfaces into horizontal and vertical equivalents (supporting sur- 

 faces and steading surfaces) we find that the resolved horizontal 

 equivalent (supporting surface) of a single winged cell forms a 

 square of which the diagonal measures 25 centimeters, and this 

 is equivalent to a rectangular parallelogram of 25 x 12.5 cm., 

 having an area of 312.5 square centimeters. 



Thus an actual silk surface of 541.5 square centimeters 

 arranged as the two wings of a winged cell, yields a supporting 

 surface of 312.5 square centimeters. 



In kites, therefore, composed exclusively of tetrahedral winged 

 cells, each having a side of 25 centimeters, the area of support- 

 ing surface bears the same proportion to the actual surface as 

 the numbers 3,125 to 5,415 ; or 1 to 1.7328. 



