Figure 15. — "Steelyard barometer" as shown in 

 Charles Hutton's Mathematical and Philo- 

 sophical Dictionary (London, 1796, vol. i, 

 p. 188). Hutton makes no reference to the 

 originator of this instrument; he attributes 

 the "Diagonal" (or inclined) barometer to 

 Samuel Morland. 



Stimulation to the staff in the invention of other 

 instruments." '^ 



From 1875 the question was no longer one of the 

 introduction of self-registering instruments to major 

 observatories but their complete mechanization and 

 the extension of registration to substations. Having 

 accepted self-registration, meteorologists turned their 

 attention to the simplification of instruments. In 

 1904 Charles Marvin, of what is now the U.S. Weather 

 Bureau, brought the self-registering barometer into 

 something of a full circle by producing an instrument 

 (fig. 14) that was nothing more than Hooke's wheel 

 barometer directly adapted to recording.'^ But this 

 process of simplification had been accomplished at a 

 stroke, about 1880, with the introduction by the 



31 Abbe, op. cit. (footnote 19), pp. 263-264. 



^2 Because of its superior accuracy to the aneroid barograph, 

 Marvin's barometer was in use through the 1940's. See R. N. 

 Covert, "Meteorological Instruments and Apparatus Employed 

 by the United States Weather Bureau," Journal of the Optical 

 ■Society of America, 1925, vol. 10, p. 322. 



Parisian instrument-maker Jules Richard of a self- 

 registering barometer and a thermometer combining 

 the simplest form of instrument with the simplest form 

 of registration (see fig. 16). This innovation, which 

 fixed the form of the conventional registering instru- 

 ment until the advent of the radiosonde, seems to have 

 stemmed from a source quite outside meteorology — 

 the technology of the steam gauge. Richard's thermo- 

 metric element was the curved metal tube of elliptical 

 cross-section that Bourdon had developed several dec- 

 ades earlier as a steam gauge. Pressure within such a 

 tube causes it to straighten, and thus to move a pointer 

 attached to one end. Bourdon had opened it to the 

 steam source. Richard filled it with alcohol, closed 

 it, and found that the expansion of the alcohol on 

 heating caused a similar straightening. His baromet- 

 ric element was a type of aneroid, which Hipp had al- 

 ready used but which Richard may have also adopted 

 from a type of steam gauge. For a recording mech- 

 anism, Richard was able to use a simple direct lever 

 connection, as the forces involved in his instruments, 

 being concentrated, were not greatly hampered by 

 friction. '^ By 1900 these simple and inexpensive in- 

 struments had relegated to the scrap pile, unfortu- 

 nately literally, the elegant products of the mass attack 

 of observatory directors in the 1860's on the problem 

 of the self-registering thermometer and barometer.'* 



Conclusions 



In view of the rarity of special studies on the history 

 of meteorological instruments, it is impossible to claim 

 that this brief review has neglected no important in- 

 struments, and conclusions as to the lineage of the 



35 Both of Richard's instruments (described in Bulletin Mensuel 

 de la Societe d' Encouragement pour I' Industrie Nationale, November 

 1882, ser. 3, vol. 9, pp. 531-543) were in use at Kew by 

 1885 and at the U.S. Weather Bureau by 1888. The firm of 

 Richard Freres claimed in 1889 to have made 7,000 registering 

 instruments, of which the majority were probably thermographs 

 and barographs. At that time, certainly no other maker had 

 made more than a small fraction of this number of self-register- 

 ing instruments. The origin of Richard's thermograph seems 

 to have been the "elastic manometer" described by E. Bourdon 

 in 1851 {Bulletin de la Societe d" Encouragement pour V Industrie Na- 

 tionale, 1851, no. 562, p. 197). While attempting to restore a 

 flattened still-pipe. Bourdon had discovered the property of tubes 

 to change shape under fluid pressure. The instrument he de- 

 veloped in coiisequence became the standard steam pressure 

 gauge. 



3< A few of these instruments, such as the Marvin barograph, 

 survived for some time because of their superior accuracy. 

 Even as museum pieces, only a few exist today. 



114 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



