a 5 4. Mifcellanea Curiofd. 



E F, is a Plate applied to the fide of the Ther- 

 mometer CD, graduated into Spaces anfwerjng to 

 Inches and parts of an Inch of Mercury, in the 

 common Barometers. 



G, a Hand (landing on the Plate at the 

 height of the Mercury thereon, as it was when 

 the Inftrument was graduated, as fuppofe here at 

 ao£ Inches. 



LM, a Wire on which the Plate EF, flips .up 

 and down, parallel to the Cane of the Thermo- 

 meter CD. . . . 



K, any Point at which the Spirit ttands at 

 the time of Obfervation ; fuppofe at 3 8 on^ 

 the Spirk-Thermcmeter ' Slide the Plate EF till 

 the Hand G ftand at 38 on the Air-lW- 

 mometer, and if the Liquor therein ftand at, 

 38 likewife, then is the preffure of the Air ; 

 the fame as at the time of Graduation, 

 % q, e z but if it ftand higher, as at 30, at 1 1 

 then is the preffure of the Air greater; and 

 the divifion on the Aiding Plate againft the 

 Liquor, (hews the prefent height of the Mer- 

 cury to be twenty nine Inches feven Tenths. 

 And this may fuffice as to the manner of ufing 



iU I had one of thefe Barometers with me in, 

 my late Southern Voyage, and it never fail- 

 ed to prognoftick and give early notice of all 

 the bad Weather we had, fo that I depended 

 thereon, and made provifion accordingly 1 and 

 from my own Experience I conclude thar a ; 

 more ufefuJ Contrivance hath not. for this, 

 long time been offer for the benefit of Na- 

 vigation* 



Thefe 



