410 Dr. J. Shields on a Mechanical Device for 



Before the position of the other lines can be fixed, it is 

 necessary to ascertain the length in millimetres corresponding 

 to 1° G. of the horizontal thermometer. Let this be n millim. 



Fig. 2. 



12 3 4 



rrrn 



We have already seen that the formula for reducing the 

 height of the barometer to 0° C. is 



B =B,[l-(/3- 7 )*], 



hence the correction which must be subtracted from the 

 observed height is 



