temperature. The utility of the instrument was im- 

 mediately recognized by physicists (not by chemists, 

 oddly enough), and much ingenuity was expended on 

 its perfection over a 50-year period, in northern 

 Europe as well as in Italy. The conversion of this 

 open, air-expansion thermoscope into the modern 

 thermometer was accomplished by the Florentine 

 Accademia del Cimento about 1660. 



Galileo also inspired the barometer, through his 

 speculations on the vacuum, which, in 1643, led his 

 disciple Torricelli to experiments proving the limita- 

 tion to nature's horror of a vacuum. Torricelli's ap- 

 paratus, unlike Galileo's thermoscope, represented the 

 barometer in essentially its classical form. In his 

 earliest experiments, Torricelli observed that the air 

 tended to become "thicker and thinner"; as a conse- 

 quence, we find the barometer in use (with the ther- 

 mometer) for meteorological observation as early as 

 1649.' 



The meetings of the Accademia terminated in 1667, 

 but the 5-year-old Royal Society of London had al- 

 ready become as fruitful a source of new instruments, 

 largely through the abilities of its demonstrator, 

 Robert Hooke, whose task it was to entertain and 

 instruct the members with experiments. In the course 

 of devising these experiments Hooke became perhaps 

 the most prolific instrument inventor of all time. He 

 seems to have invented the first wind pressure gauge, 

 as an aid to seamen, and he improved the bathometer, 

 hygrometer, hydrometer, and barometer, as well as 

 instruments not directly involved in measurement such 

 as the vacuuni pump and sea-water sampling devices. 

 As in Florence, these instruments were immediately 

 brought to bear on the observation of nature. 



It does not appear, however, that we would be 

 justified in concluding that the rise of scientific mete- 

 orology was inspired by the invention of instruments, 

 for meteorology had begun to free itself of the tradi- 

 tional weather-lore and demonology early in the 17 th 



> On early meteorological instruments see A. Wolf, A History 

 of Science, Technology and Philosophy in the Sixteenth and Seventeenth 

 Centuries, New York, 1935, and E. Gerland and F. Traumiiller, 

 Geschichte der physikalischen Experimentierkurut, Leipzig, 1899. 

 On the recognition of the meteorological significance of the 

 barometer by Torricelli and its meteorological use in 1 649 see 

 K. Schneider-Carius, Wetterkunde Wetterforschung, Freiburg and 

 Munich, 1955, pp. 62, 71. 



Figure i. — A set of typical Smithsonian 

 meteorological instruments as recommended 

 in instructions to observers issued by the 

 Institution in the 1850's. Top (from left): 

 maximum-minimum thermometer of Pro- 

 fessor Phillips, dry-bulb and wet-bulb ther- 

 mometers, and mercurial barometer by 

 Green of New York. Lower left: rain gauge. 

 The wet-bulb thermometer, although typical, 

 is actually a later instrument. The rain 

 gauge is a replica. {Smithsonian photo 46/40.) 



PAPER 23: THE INTRODUCTION OF SELF-REGISTERING METEOROLOGICAL INSTRUMENTS 



97 



