1. The gold foil mounted on paper was kindly supplied by W. F. Grupe of the Peerless Roll Leaf Company, Union City, New Jersey.
2. Scotch Weld No. 588 manufactured by Minnesota Mining and Manuacturing Company.
3. For a description of the ideal theory, see, e.g., Glass, Martin, and Patterson, UTIA Report No. 2, University of Toronto Institute of Aerophysics (1953).