432 XXI. England. — Greenwich. Laf. 51° 29' N. ; Lo7ig. 0° 0'. 



Conections to be applied to the Means of the Hours of Observation, or Sets of Hours, 

 to obtain the true Mean Barometric Pressure for the respective Months. — Glaisher. 



D 



The numbers without sign must be added ; those with the sign — must be subtracted. 



92 



