4 steam vessels so as to secure a continuous line of observation s all the way across the Atlantic.
Hargrave introduced what is known as the cellular construction of kite. H e constructed kites compose d of many cells, but found no substantial improvement in many cells over two alone; and a kite composed of two rectangular cells separated by a considerable space is now universally known as the Hargrave box kite. This represents in my opinion, the high water mark of progress in the nineteenth century; and this form of kite forms the starting point for my own researches.
The two cells are on the same horizontal level — one constituting the front cell of the kite, the other the rear. They are connected together by a framework so that a considerable space is left between the fore and aft cells. This space is the most essential/feature of the kite: Upon it depends the fore and aft stability of the kite. The greater the space — the more stable is the equilibrium of the kite in a fore and aft direction — the more it tends to assume a horizontal position — and the less it tends to dive or pitch.
Each cell is provided with vertical sides; and these again seem to be essential elements of the kite contributing to lateral stability. The greater the extent of the vertical sides — the greater the stability in the lateral direction — and the less tendency has the kite to roll, or move from side to side — or turn over in the air. The following is a drawing of a typical form of Hargrave kite: