Figure 2. — A contemporary drawing of Wren's "weatiier clock." (Photo 

 courtesy Royal Society of London.) 



shows an ordinary clock to which is attached a pencil- 

 carrying rack, geared to the hour pinion. A discus- 

 sion of the clock's "reduction to practice" began the 

 involvement of Robert Hooke, who was "instructed" 

 in September 1664 to make "a pendulum clock 

 applicable to the observing of the changes in the 

 weather." ^ This tribute to Hooke's reputation — and 

 to the versatility of the mechanic arts at this time — was 

 slightly overoptimistic, as 15 years ensued before the 

 clock made its appearance. 



References to this clock are frequent in the records 

 of the Royal Society — being mainly periodic injunc- 

 tions to Hooke to get on with the work — until its 

 completion in May 1679. The description which 

 Hooke was asked to supply was subsequently found 



8 R. T. Gunther, Early Science in Oxford, vol. 6, The Lije and 

 Work of Robert Hooke, pt. 1, Oxford, 1930, p. 196. In 1670, 

 Hooke's proposed clock was referred to as "such a one, as Dr. 

 Wren had formerly contrived" (Gunther, p. 365). 



among his papers and printed by William Derham as 

 follows: ' 



The weather-clock consists of two parts; first, that which 

 measures the time, which is a strong and large pendulum- 

 clock, which moves a week, with once winding up, and is 

 sufficient to turn a cylinder (upon which the paper is rolled) 

 twice round in a day, and also to lift a hammer for striking 

 the punches, once every quarter of an hour. 



Secondly, of several instruments for measuring the degrees 



5 William Derham, Philosophical Experiments amd Observations 

 oj . . . Dr. Robert Hooke, London, 1726, pp. 41-42 (reprinted 

 in Gunther, op. cit. footnote 8, vol. 7, pp. 519-520). This 

 description, dated December 5, 1678, predates the Royal 

 Society's request for a description (Gunther, op. cit. footnote 

 8, p. 656) by four months, but the Society no longer has any 

 description of the clock. As to the actual completion of the 

 clock, the president of the Society visited "Mr. Hooke's turret" 

 to see it in January of 1678/79 but it was not reported 

 "ready to be shown" until the following May (Gunther, 

 pp. 506, 518). 



100 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



