186 ANNUAL OF SCIENTIFIC DISCO VERY. 



ATMOSPHERIC OZONE. 



The following comprehensive paper on atmospheric ozone was 

 presented to the British Association (1861 meeting) by Dr. Mofiatt, 

 F. K S.: 



The mean daily quantity of ozone is greater with readings of the 

 barometer below than above the mean, and greater when the range 

 of the barometer and the number of its oscillations are above the 

 mean. It is greater when the mean-daily and dew-point tempera- 

 tures are above the mean, but greater when the degree of humidity is 

 below than when above the mean. When the wind is from points of 

 the compass between north-west and south-east-by-north above the 

 mean number of times, ozone is at its minimum, and when it is in 

 points south of these above the mean number, it is at its maximum. 

 It is also at its maximum when the wind is above its mean force. 

 When rain is above the mean quantity, ozone is also at its maximum, 

 and also with hail ; but the quantity is smaller on days with snow and 

 sleet than on days without them. With fog it is below the mean 

 quantity. It is above it with cirri, halos, aurora?, and the zodiacal 

 light, but below it with thunder, thunder and lightning, and thunder 

 storms ; and it is at its maximum with negative, and minimum with 

 positive, electricity. The mean daily quantity is greater with_ de- 

 creasing than with increasing readings of the barometer, and it is 

 three times greater with wind in points south of east and west, than 

 it is in points north of these, the greatest quantity (3.5) with south- 

 west, and the smallest (0.8) in the north-east points. Ozone periods 

 may be said to commence invariably with decreasing readings of the 

 barometer and increase of temperature, and with winds from south 

 points of the compass ; and to terminate with increasing barometer 

 readings, decrease of temperature, and wind from north points of the 

 compass. These results are from two hundred and ninety-six periods. 

 By far the greatest number of ozone periods commence in south-east, 

 and a great majority terminate in north-west points. Indeed, although 

 the commencement of ozone periods in north-west points is not uncom- 

 mon, the south-east may be called the points of their commencement, 

 and the north-west the points of their termination. The quantity of 

 ozone is greater in the night than in the day. It is greater with new 

 and full moons than with the first and last quarters, and it also varies 

 with the seasons. It is greater in January, February, and March, 

 than in April, May, and June ; but greater in the latter months than 

 in July, August, and September. In these it is at its minimum, and 

 it again increases in October, November, and December. The great- 

 est quantity is in April (2.3) and December (2.4), and the smallest 

 in July (1.3) and August (1.3). The greatest number of ozone days 

 is in April (25), and the smallest in August (19) and November (17). 

 Whatever tends to a deflection in the direction of the wind leads to 

 a corresponding result in ozone observations, and a town, chemical 

 works, drains, and cesspools, in fact, at any locality in which the pro- 

 ducts of combustion and decomposition are in sufficient quantity to 

 decompose ozone, the air will be de-ozonized, and the wind or cur- 

 rent passing over it will be non-ozoniferous. The quantity of ozone 

 increases with increase of elevation above the level of the sea. The 



