BAROMETER TO SEA LEVEL. 9 
and the table may be calculated from the value of pa ; in the same 
way as when Table A is employed. 
A table for reducing the barometer to sea level is furnished from 
the Central Office, Toronto, to each station in connection with the 
Meteorological Service of the Dominion. 
Formerly these were computed directly from formula iii. (using 
a slightly different constant from that given above.) The accom- 
panying tables were recently calculated to diminish the labour of 
computation. 
In Canada, no reduction for height is applied to the observed 
temperature of the air; as, although some correction might be of 
advantage, it is by no means certain that a correction, obtained from 
observations on a mountain, would be suited to a station on an 
elevated table-land. The correction, if it were applied, would, how- 
ever, be very small at nearly all our stations. 
I hope to discuss, more fully, on some future occasion the question 
of the necessity for a correction to the observed temperature of the 
air in reducing barometric readings, 
