13.(Pg. [140]) In ascertaining the weight of air, we take account of its temperature—Why?
14.(Pg. [140]) How could you ascertain the specific gravity of air, and what would it be?
15.(Pg. [140]) What are the essential parts of a barometer, as represented [plate 14, fig. 3]?
16.(Pg. [141]) What sustains the mercury in the tube?
17.(Pg. [141]) Of what use are the divisions in the upper part of the instrument?
18.(Pg. [141]) To what height will the mercury rise, and what occasions this height to vary?
19.(Pg. [141]) When is the mercury highest, in wet, or in dry weather?
20.(Pg. [141]) What occasions the sensation of oppression, in damp weather?
21.(Pg. [142]) Why will the barometer indicate the height of mountains, or of balloons?
22.(Pg. [142]) Is any inconvenience experienced by persons ascending to great heights, and from what cause?