7 
322 Description of a new portable Barometer. 
Fig. 1 is asection of the baro- 
meter cistern, showing the manner 
in which the tube and thermometer 
are placed. 
The dotted line marks the height 
of the mercury, the space above 
being filled with air. 
Fig. 2 is the barometer in its 
finished state, in which the diffe- 
rent parts are represented as they 
appear when the sliding tube is 
turned round and the -cap at top 
unscrewed, 
[ApRIL, 
