Featured on PDR in the collection Alexander Graham Bell’s Tetrahedral Kites (1903–9)

Although best known for developing the practical telephone — for which he became the first, in 1876, to secure a US patent — the Scottish-born inventor Alexander Graham Bell is also noted for his work in aerodynamics, a rather more photogenic endeavour perhaps, as evidenced by the wonderful imagery documenting his experiments with tetrahedral kites. The series of photographs depict Bell and his colleagues demonstrating and testing out a number of different kite designs, all based upon the tetrahedral structure, to whose pyramid-shaped cells Bell was drawn as they could share joints and spars and so crucially lessen the weight-to-surface area ratio.