One can only wish for further information on the 

 mechanism by which the punches — or in Wren's 

 clock, the pencils — ^were moved. But it is apparent 

 that Hooke's clock was actually used for some time. 



The 17th century was not entirely unprepared for 

 the idea of such a self-registering instrument. Water 

 clocks and other devices in which natural forces 

 governed a pointer were known in antiquity, as were 

 counters of the type of the odometer. A water clock 

 described in Italy in 1524 was essentially an inversion 

 of one of Hooke's rain gauges, that in which a bucket 

 was balanced against a string of bullets.'^ The 

 mechanical clock also had a considerable history in 

 the 17th century, and had long since been applied 

 to the operations of figures through cams, as was 

 almost certainly the case with the punches in Hooke's 

 clock. Still, the combination of an instrument- 

 actuated pointer with a clock-actuated time-scale 

 and a means of obtaining a permanent record 

 represent a group of innovations which certainly 

 ranks among the greatest in the history of instrumenta- 

 tion. It appears that we owe these innovations to 

 Wren and Hooke. 



Hooke's clock contributed nothing to the systema- 

 tization of meteorological observation, and the last 

 record of it appears to have been a note on its "re- 

 fitting" in 1690. Its complexity is sufficient reason 

 for its ephemeral history, but complexity in machine 

 design was the fashion of the time and Hooke may 

 have intended no more than a mechanistic tour de 

 force. On the other hand, he ixiay have recognized 

 the desideratum to which later meteorologists fre- 

 quently returned — the need for simultaneous obser- 

 vations of several instruments on the same register. 

 In any case, no instrument so comprehensive seems 

 to have been attempted again until the middle of the 

 19th century, when George Dolland exhibited one 

 at the Great Exhibition in London (see fig. 3). 

 The weather elements recorded by Dolland's instru- 

 ment were the same as those recorded by Hooke's, 

 except that atmospheric electricity (unknown in 

 Hooke's time) was recorded and sunshine was not 

 recorded. Striking hammers were used by Dolland 

 for some of the instruments and "ever pointed 

 pencils" for the others. Dolland's barometer was a 

 wheel instrument controlling a hammer. His ther- 



'^ Battista della Valle, Vallo Libra Continente Appertiniente ad 

 Capitanii, Retenere and Fortificare una Citta . . . , Venetia, 1523 

 (reported under the date 1524 in G. H. Baillie, Clocks and 

 Watches, an Historical Bibliography, London, 1951). 



mometric element consisted of 12 balanced mercury 

 thermometers. Its mode of operation is not clear, 

 but it probably was similar to that of the thermometer 

 developed by Karl Kreil in Prague about the same 

 time (fig. 4). Dolland's wind force indicator con- 

 sisted of a pressure plate counterbalanced by a string 

 of suspended weights. Altogether, it is not clear 

 that Dolland's instrument was superior to Hooke's, 

 or that its career was longer.^' 



The 171 years between these two instruments were 

 not lacking in inventiveness in this field, but even 

 though inventors set the more modest aim of a self- 

 recording instrument for a single piece of meteor- 

 ological data, their brain children were uniformly 

 still-born. Then, during the period 1840-1850, we 

 see the appearance of a series of self-registering 

 instruments which were actually used, which were 

 widely adopted by observatories, and which were 

 superseded by superior instruments rather than 

 abandoned. This development was undoubtedly a 

 consequence of the establishment at that time of 

 permanent observatories under competent scientific 

 direction. 



Long experience had demonstrated to the meteor- 

 ologists of the 1840's that the principal obstacle to 

 the success of self-registering instruments was friction. 

 Forbes had indicated that the most urgent need was 

 for automatic registration of wind data, as the erratic 

 fluctuation of the wind demanded more frequent 

 observation than any manual system could accom- 

 plish. Two of the British Association's observers 

 produced separate recording instruments for wind 

 direction and force in the late 1830's, a prompt 

 response which suggests that it was not the idea 

 which was lacking. One of these instruments — 

 designed by William Whewell — contained gearing, 

 the friction of which vitiated its utility as it had that 

 of a number of predecessors. The other, designed by 

 A. Follet Osier, was free of gearing; it separately 

 recorded wind pressure and direction on a sheet of 

 paper moved laterally by clockwork. The pressure 

 element was a spring-loaded pressure plate carried 



1' Dolland's instrument, called an "atmospheric recorder," is 

 described in the Official, Descriptive and Illustrated Catalogue to the 

 Great Exhibition, 1851, London, 1851, pt. 2, pp. 414-415. As 

 the George Dolland who joined the famous Dolland firm in 

 1804 would have been about 80 years of age in 1850, the George 

 Dolland who exhibited this instrument may have been a younger 

 relative. 



PAPER 23: THE INTRODUCTION OF SELF-REGISTERING METEOROLOGICAL INSTRUMENTS 103 



578767—61 2 



