JOSEPHAGASSI WHODISCOVEREDBOYLE'SLAW?* Preface THE PRESENT essay illustrates a historiographic point and makes a historical point. The historiographic point is this: in the history of science, unlike other histories, error and redundancy tend to proliferate, perhaps due to the absence of a traditional requirement from a writer to declare his interest, state his problem, express his viewpoint, and list the difficulties he leaves not yet solved to his own satisfaction. (See [Agassi, (a)], especially final section.) My example here is an error which tallies very well with the 19th century climate of opinion, according to which Robert Boyle observed facts which his assistant Richard Townley generalized into the celebrated gas law. This error has been criticized by Gerland in 1909 and in 1913, but his criticism was ignored. Later writers have made extensivegtudies, culminating with those of Webster and Cohen in recent years. Yet the later extensive documentation only confuses matters because even the simplest criteria used are not openly * The present essay grew out of a brief appendix to my doctoral dissertation, University of London, 1956, unpublished. This is not a priority claim, since the main thesis of this essay goes to Ernst Gerland, 1909 and 1913 (see bibliography at the end of this essay): Boyle’s law was discovered by Boyle. The essay grew out of attempts to cope with comments by editors and their referees, as well as by friends and colleagues. Some of these comments save me much embarrassment by correcting some of my worst errors; some are very clever suggestions; others were not so intelligent: those below a certain level of intelligence I simply could not cope with within the framework of this essay. Two major factors of expansion were the new contributions to the topic - which will be discussed below - and a brief section in physics proper. Now the new contributions perpetrate errors which are discussed in my original appendix. Most editors who have rejected early versions of this essay have claimed that these errors are so obvious as to be in no need of correction in the learned press. The physics included in section 2 below, on the gas law, is included because most of the comments I received were based on errors in physics which I felt 1 had to take care of. My presentation of that chapter in physics was viewed by a learned historian of science and editor of a first rate journal, as most unsatisfactory, as it presents that chapter in physics somewhere between the historical manner of how it looked in the seventeenth century and the really up-to- date. I think he is right, but will leave my presentation as it is, since it is a simplified and serviceable version of what most physicists offer on the subject. That editor was willing to publish the historical core of this essay were I ready to omit my comments on other writers on the topic, which seemed to him merely polemic and so pointless. Some people will never see any use in the survey of past errors, as if error is so quaint a part of the human understanding that it can be left to students of oddities. I think this inability to alter one’s attitude towards human error is the major target of most of my work in this area, especially [Agassi (a)]. The translations from Gerland. Rosenberger, and Heller are mine; the beginning of the Rosenberger translation, however, is from Ornstein (p. 52). Square brackets refer to the bibliography at the end of this essay. Unspecified page numbers refer to Robert Boyle’s Works, Volume 1, unless specified otherwise A = 1st ed; B = 2nd ed. I am grateful to Gerd Buchdahl, Daniel A. Greenberg, Yehuda Elkana, Russel McCormmack, and C. Truesdell, for their comments on earlier versions. Stud. Hivt. Phi/. Sci. 8 (1977). No. 3. Printed in Great Britain. 189