( i6i^ ) 
IL Jn Experiment y to fhow the caufe of the defcent of 
the Mercury in the (Barometer in a Storm, By Mr 
Francis Hauksbee. 
IN the late Violent Storm or Hurricane of Wind, it 
was obfervable that the Mercury in the Barometer 
did not only confiderably fubfide, but upon Extraordi- 
nary Gufts a Vifibie Vibration of the Quickfilver ap- 
pear'd. And for facisfadion of the Curious, That High 
Winds are capable to lefien the Prefliire of the Atmo- 
fphere, an Experiment hss lately been Devis'd, and 
made at a meeting of the Royal Society at Grefiam-Coh 
ledge^ ^prH the iith, 1704. by Mr Fra. Hd^J{shee^ giving ' 
a DemonftratioG of this Phenomenon, A Defcription of . 
which take from the Delioeatioo, Fig. 12. The Recipi» 
ent- ..A. contaimog-about 5 quarts,, having about 5 or 4 
times its Natural quantity of Air coniprefi in it by the 
Syphon^ B. B. VVhkh for that purpofe n fcrew'd 00 at 
the Bottom within the ''fide of the Bafon ,C The Stop-^ 
cock being turo'd, and the. Syphon . taken orFi -a 
fmall Swan-neck Pipe .E/is fcr^ w'd on in its place. The 
nofe of which fits into a Brafs Socket, which is fixt in a 
Gubical piece of Wood .F., right agaioft the Iiorizontal 
pipe <G> From the fame Cubical piece .F- arlfes --^ 
Miked. Eas:cmeter .H. H- whofe Ciftern iyes open to the 
piflage v„^hich leads from the Swan-neck Pipe to the , 
Horizontal . Tube aforefaid. Likewife fro|i) the fame 
Piece proceeds another Pipe or Tube parallel to 
the Horizon diftinguifb/d by leading to another 
Cubicar Piece of Wood .K, g loot diftant from the for- 
mer : Out of which Ukewii€ arjfeth another Barometer 
X. L. whofe Ciftern is '^Ub open t(.> the Horizontal Tube 
J. and by that means hath Communication with the- 
open 
