“Give Me a Telescope and I Shall Move the Earth”: Hooke's Attempt to Prove the Motion of the Earth from Observations

Abstract

1. INTRODUCTIONNe miremur tam tarde erui quae tam altejacent. This epigraph by Seneca1 opens Hooke's An attempt to prove motion of Earth from observations2 and can be translated as follows: is no wonder I took so long to unearth what lies so deep. Yet meaning of sentence should be reversed. In context of his astronomical tract, Hooke played upon words by using double meaning of alte: high and deep.3 Thus sentence should read: is no wonder I took so long to discover what stands so high. At outset of his astronomical Attempt, Hooke thus indicated that he had somehow found means to reach and see what had hitherto remained inaccessible. With his telescopic observations of apparent motion in position of Gamma Draconis, he could show and measure stellar parallax of globe of Earth. This was long sought for proof, he asserted, of motion of Earth around Sun.The Attempt was one of Hooke's famous Cutlerian Lectures, delivered in 1670 and published in 1674.4 The general context of this publication was debate with Hevelius over use of telescopic sights in astronomical observation.5 The controversy had started in 1668 with Hooke's sending to Hevelius through Oldenburg instructions on how to build and use telescopic sight, and Hevelius's declaring himself radically against it. It is no coincidence that both Attempt and Animadversions on first part of Machina coelestis of... Johannes Hevelius (another Cutlerian Lecture) were published in 1674, when dispute was raging, following publication of Hevelius's Machina coelestis in 1673. Hooke's two Cutlerian Lectures could therefore be construed as a double attack: firstly, a demonstration of power of telescopic sight for angular measurement in Attempt, and secondly, a direct engagement with Hevelius in Animadversions.However, epigraph suggests one should look for a greater ambition. Beyond immediate context of controversy over a new type of astronomical instruments, I shall suggest that Hooke engaged with two major astronomical traditions: Copernican conception of celestial harmony, and Tychonic procedures of astronomical observation. This article explores Hooke's ambition to radically reform astronomical practice. The use of an archetypal astronomical question - debate over heliocentrism - was a case in point and a way for Hooke spectacularly to demonstrate efficiency of his experimental method. No wonder no one succeeded in discovering parallax before Robert Hooke: he was first, so he said, to possess a telescope that was sufficiently accurate to allow required measurements.2. THE QUESTION OF HARMONYBy 1650, Copernicanism had become a broadly accepted hypothesis amongst British astronomers. The rationale for this acceptance, however, was not grounded on demonstration. While Hooke's prime and most easily identifiable opponents were anti-Copernicans, I shall suggest that Copernicans themselves and their current observational methods and practices were of at least equal concern to Hooke. The beginning of text, however, announced and circumscribed a seemingly archetypical debate over heliocentrism and geocentrism:Whether Earth move or stand still hath been a Problem, that since Copernicus revived it, hath much exercised Wits of our best modern Astronomers and Philosophers, amongst which notwithstanding there hath not been any one who hath found out a either of one or other Doctrine. The more knowing and judicious have for many plausible reasons adhered to Copernican Hypothesis: But generality of others, either out of ignorance or prejudice, have rejected it as a most extravagant opinion.6This first paragraph clearly set out problem: there was no certain manifestation to help one decide between two hypotheses. In this matter, Hooke insisted, the controversy . …