ment and the actual velocity of the wind.[30] Beckley and Draper
caused it to move a pencil through gearing; the others used with it
electromagnetic counters actuated by rotating contacts.

[Illustration: Figure 10.--Chart from Secci's meteorograph. (From
Lacroix, _op. cit._ footnote 22.)]

As has been indicated, the Signal Corps used all six systems, a panoply
of gadgetry which must have been wondrous to behold. Its Secci
meteorograph, which had attracted much attention at Paris, was estimated
to have cost 15,000 francs. Abbe reported in 1894 that the instruments
were long kept in the apparatus room "as a fascinating show to visitors
and a stimulation to the staff in the invention of other
instruments."[31]

[Illustration: Figure 11.--Draper's mechanical registering barometer,
as used in the Lick Observatory. (Photo courtesy Lick Observatory.)]

[Illustration: Figure 12.--Hough's electromechanical registering
barometer, about 1871.]

[Illustration: Figure 13.--Fuess' "balance barometer after Samuel
Morland," 1880. Wren probably was the originator of this type of
instrument. (From Loewenherz, _op. cit._ footnote 28.)]

[Illustration: Figure 14.--Marvin's mechanical registering barometer,
1905. This instrument was formerly in the U.S. Weather Bureau. (_USNM
316500_; _Smithsonian photo 46740-E_.)]

[Illustration: Figure 15.--"Steelyard barometer" as shown in Charles
Hutton's _Mathematical and Philosophical Dictionary_ (London, 1796, vol.
1, p. 188). Hutton makes no reference to the originator of this
instrument; he attributes the "Diagonal" (or inclined) barometer to
Samuel Morland.]

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.[32] But this process of simplification had been accomplished
at a stroke, about 1880, with the introduction by the Parisian
instrument-maker Jules Richard of a self-registering barometer and a
thermometer combining the simplest form of instrument with the simplest
form of regist