UM IMPIKINIMINICHWY.IPIWIAMP...... of rain that has fallen. The preceding E sketch, taken from the first half of a t minommilotIMMIImNINMEINNI A it ”y• regser-slieet, ivies an idea of the kind of record made by an Osler's 1111111111= A. The space between two upright la lines indicates an hour; that between =7.reffai rwr-T s two horizontal lines, in the rain-re gga • ..M"'" inter -A e.
Y6 of an inch of rain, in the direc 12 2 3 4 6 6 7 6 9 ie a 12 tion of the wind two cardinal points, Register-sheet of an Osler's anemometer. and in the force of the Wind 1 lb. of pressure on the square foot.
Thus, on the day in which these lines were traced, there was in the rain-register, brought over from the former account, between .10 and .15 of an inch; and during the 12 11., the pencil had only risen one space, indicating is fall of .05, or -h. of an inch. almost entirely between the hours of.8 and 4 ht the morning, and immediately before 12 In the day. If the day had been very rainy, and the pencil had risen to the top of the register, it would have fallen immediately to the bottom of it, and begun a new account: and it might have done so several times in the course of the twelve hours. This would have been effected by the mechanism connected with the rain-gauge, which enables the gauge to empty itself each time that the pencil reaches the top of the rain register. As
regards the direction of the wind, it was, during the first six hours, s., veering slightly towards the C.; and for the last six hours, it was tending decidedly towards the w., being between 10 and 11 nearly west. From the line marking the force of the wind, it will be seen that the day was stormy. Between 1 and 2, and at 11, the wind was blowing a very high gale, producing a pressure of upwards of 12 lbs. on the sq.ft.; and between the hours of 4 and 5, there was it decided lull, the wind being brisk, but not stormy (2 to d lbs.). Both the hemispherical-cup A. and the pressure A. are equally indispensable in fully equipped observatories. The former registers the quarterly wind which passes over the place, but cannot register the force of those sudden and almost instantaneous gusts of wind to which storms and hurricanes owe their destructive energy.
In Lind's A., the wind, entering the mouth of one of two upright glass tubes, con nected below, depresses the column of water contained in the one tube, and raises pro portionately that in the other. This A. is convenient for rough purposes.