322 REPORT—1840. 
two points of the compass; it is therefore not always prac~- 
ticable to attain exact accuracy; in all such doubtful cases, I 
have taken that which, on the whole, appears to be the nearest 
oint. 
i It must be borne in mind, that it is the force and direction 
of the wind that this instrument records, and not velocity, 
which the valuable and ingenious instrument invented by Pro- 
fessor Whewell is intended to register. 
But though the oscillations of the vane offer a difficulty for 
the reason just stated, yet it affords a remarkable distinction 
between different winds, and even between the same wind at 
different times. During a north wind, for instance, the vane is 
generally steady, while during a N.E. and E.N.E. wind the 
oscillation is frequently considerable. A south wind, too, is some- 
times very steady, and at other times the reverse; but not hav- 
ing had time to investigate this peculiarity, I merely mention it 
for the purpose of inviting attention to the circumstance; as a 
knowledge of the cause that produces this difference, if fully un- 
derstood, may prove valuable to the meteorologist. 
A sheet on the plan of Table I. having been drawn out for 
every month during the four years, I proceeded by taking an 
abstract of each month as shown in Table II., and thus ob- 
tained the total of the forces of each wind for the twenty-four 
hours during the month. 
Plate III. fig. 1 is a diagram drawn from the general totals 
(marked +) in Table III., showing at one view the direction and 
sum of the forces of the wind for each hour of the day, as re- 
gistered at Birmingham, during the years 1837-8—9-40. 
Plate IV. represents the comparative direction and forces of 
each wind during the twenty-four hours, distinguishing the 
quarters of the year. See ‘Table IV. 
Plate V. contains diagrams, showing the comparative force 
and direction of each wind, obtained from the sum of the hourly 
means in Table III. (marked {). See also Table VI. 
Plate I. fig. 2 is projected from Table V., and exhibits the 
comparative force of the wind for each of the twenty-four hours, 
direction not being regarded. In this Plate the coincidence 
between the curve of force and of temperature is very remark- 
able, the temperature preceding the rise of the wind by a short 
interval. 
The whole of these tables must be regarded merely as com- 
parative; I have therefore not considered it necessary or de- 
sirable to reduce the total amounts to obtain the mean force 
per day or per hour, as it would merely add to the labour and 
sources of error without effecting any equivalent practical 
