Beginning with an overview of Galileo's earliest work on free fall, the paper examines the relationship between experiment and theory in his study of motion in the period immediately before and after 1604. The possible role of experiment is assessed in relation to the manuscript evidence and by means of reconstructed experiments.

Summary One aim of this paper is to provide an assessment of the recent attempts to interpret the development of Galileo's theory of motion in the late Paduan period 1604?1610. In addition to this a new interpretation of this process of development is advanced. This interpretation is the first that proves able to provide a full account of all the features on folio 152r of volume 72 of the Galilean manuscripts which has been claimed to be of crucial significance. The (...) major feature of the interpretation is that it is the first to account for the relationship between Galileo's theoretical and experimental work in the period 1604?1610. (shrink)

Recent study of Galileo's surviving manuscript notes on motion has revealed that by 1609 he had developed the major part of his theory of projectile motion. During the period of these theoretical advances Galileo was engaged in important related experimental investigations; this has become clear from the study of folios 114r and 116v of the manuscript on motion. This paper provides an interpretation of a manuscript not previously discussed—folio 81r. The analysis provided indicates that it is evidence of an important (...) early experiment of the series in which Galileo studied the projectile trajectory. The reconstruction of the experiment concerned reveals relationships with the enquiries suggested by folio 114r and 116v and indicates that Galileo examined the form of projectile trajectories with some care. (shrink)