K R 



Figure 9. — Front and rear views of Seed's meteorograph, 1867. (From 

 Lacroix, op. cit. footnote 22.) 



Hough's barometer was an adaptation of the elec- 

 trical contact thermometer. The movement of the 

 mercury over a certain minute distance within the 

 tube served as a switch to energize an electrical 

 recording system. Hipp, who was perhaps the latest 

 of this group, first applied the aneroid barometer 

 (fig. 8) to self-registration. The idea of the aner- 

 oid — an air-tight bellows against which the atmos- 

 pheric pressure would act — had been advanced by 

 Leibniz in the 17th century and had been the subject 



ideas to a friend. But Morland's was probably the inclined 

 and not the balance barometer. (.See under "barometer" in 

 Charles Hutton, Mathematical and Philosophical Dictionary, 

 London, 1796, vol. 1; also J. K. Fischer, Physikalisches Worter- 

 buch, Gottingen, 1798). 



of a few abortive experiments in the 18th century. 

 Not until 1848 was an instrument produced that was 

 acceptable to users of the barometer.^' 



As a wind velocity instrument all si.\ systems used 

 the cup-anemometer developed by Robinson in 1846, 

 an instrument whose chief virtue was the care which 

 its in\-entor had taken to work out the relationship be- 

 tween its movement and the actual velocitv of the 



-' Leibniz, in several letters — beginning with one to Denys 

 Papin on June 21, 1697 — proposed the making of a barometer 

 on the model of a bellows. Of subsequent versions of such a 

 barometer, that of Vidi (described by Poggendorff, Annalen der 

 Physik und Chemie, 1848, Band 73, p. 620) is generally regarded 

 as the first practical aneroid (see also Gerland and TraiimuUer, 

 op. cit. footnote 1, pp. 239, 323). 



PAPER 23: THE INTRODUCTION OF SELF-REGISTERING METEOROLOGICAL INSTRUMENTS 



109 



