1. N. Oresme, The Book on the Heavens and on the Earth in A Source Book in Medieval Science, E. Grant (ed.) ( Cambridge, Mass., 1974 ), p. 504.
2. For a discussion of the notion of independent testability, see K. R. Popper, ‘The Aim of Science’ in Objective Knowledge (Oxford, 1979 ), pp. 191–205.
3. See especially S. Drake, ‘Galileo’s Experimental Confirmations of Horiztonal Inertia: Unpublished Manuscripts’, Isis
LXW, 1973, pp. 291–305.
4. For documentation of this point see, for example, W. L. Wisan, The New Science of Motion: A Study of Galileo’s De Motu Locali, Archive for History of Exact Sciences XIII, 1974, pp. 103–306 and S. Drake, Galileo at Work (Chicago, 1978 ).
5. On this point see M. Clavelin, The Natural Philosophy of Galileo (Cambridge, MA., 1974), Chapter 3; S. Drake, Galileo Studies (Ann Arbor, 1970), Chapter 1; and W. R. Shea, Galileo’s Intellectual Revolution (London, 1972 ), Chapter 1.