THE ATMOSPHERE 



IS 



great waste of mercury must occur even in experienced hands. The mercury 

 used in the foregoing experiment must be perfectly dry. 



This instrument is known as the barometer (weight-measurer). 

 Owing to the relation that exists between the atmospheric 

 pressure and the weather, it becomes a useful weather glass. 

 Repeat the observation of the height of the mercury column 



Fig. 3. 



at the same hour daily for one month, marking each observation 

 by means of a dot on the accompanying chart, and at the same 

 time record the character of the weather {e.g. wind, rainfall, 

 temperature, and sunshine) in the notebook. At the end of 

 the period, connect the dots on the chart by straight lines, and 

 compare the rise and fall with the variations in the weather. 



