GEAHAM bell's TETRAHEDRAL KITES. 185 



winged cells without horizontal aeroplanes constitute the best arrange- 

 ment of aero-surfaces. 



"The tetrahedral principle enables us to construct out of light mate- 

 rials solid frameworks of almost any desired form, and the resulting 

 structures arc admirably adapted for the support of aero-surfaces of 

 any desired kind, size, or shape." 



The diagrams illustrating the article show various examples of the 

 formation of complex kites from tetrahedral cells. One form sug- 

 gested by Professor Langley's aerodrome, but different in construc- 

 tion and appearance, is shown in fig. 4, reproduced from an illustration 

 in the article. That some of these complex kites are on a very large 

 scale is evident from a case cited, in which an aerodrome kite, which 

 was struck by a squall before it was let go, lifted two men off their 

 feet, and subsequently broke its fljang cord, a Manila rope of three- 

 eighths inch diameter. 



The simplicitv of the construction of the cells, and the obvious pos- 

 sibilities of their combination, lend an additional fascination to a sub- 

 ject which is already full of interest. 



