xm. 



NOTES ON THE METEOROLOGY AND MORTALITY OF 

 THE MONTH OF JULY, 1871. 



By E. Swarbreck Hall. 



The weather this month was unusually wet, windy, and warm, with great 

 mutations of atmospheric pressure, and an excessive daily-range of tempera- 

 ture, together with ozone above the average. It is very remarkable that 

 exactly one-half of all the deaths were at and above GO years of age, while 

 deaths under 20 years old were less than one-fifth of the whole. The total 

 deaths were about 24 per cent, less than the July average for the previous 14 

 years. 



Atmospheric-pressure, 20"G84, was — "160 below the average. The extreme 

 range of the month was 1'581 inches, being the largest on record. The 

 extremes were : maxiiiiuu:', 303."^9 on the 22nd ; minimum, 28758 on the 

 17th. So low a minimum has only been registered seven times in the last 30 

 years. There was no excess of wind in Hobart Town, but great storms were 

 reported elsewhere. The greatest movement of the barometer in any twenty- 

 fours from 1 p.m. to 1 p.m. was a fall of — '600 of an inch on the 14th, but 

 on four other days there were movements of more than half an inch. Al- 

 together there were 18 days on which the variations exceeded one-fifth of an 

 inch, which is without parallel in the Hobart Town records. As is usual 

 these excessive fluctuations of atmospheric pressure caused many deaths 

 amongst old and debilitated people. 



Wind-force ioi&X, 60'Oi lbs., was + 20 '46 lbs. above the July average. At 

 67 out of the 93 observations, with 30 "So lbs. of the force, the wind was 

 registered from the north-west, but there is no doubt that many of them were 

 really deflected west winds from theu' high ozonic character. It is, as has 

 often been before noted, that owing to the sudden angle in the valley of 

 the Derwent at Bridgewater eleven miles from the city, caused by the Mount 

 Wellington tier, winds from the west are liable to be deflected towards the 

 north-west. "West and south-west winds were 13 in number with 18 "22 lbs. 

 of the force. The other winds were unusually below the average in both 

 aspects. The strongest winds had only 5 '21 lbs. i^ressure to the square foot, 

 and were registered only three times. Calms were 23, being — IG'89 below 

 the average. 



Temperature mean, 48'85 degrees, was -1- 3'13 above the 25 years' average. 

 In the jjrevious 30 years there have only been 4 Julys with a higher tem- 

 peratm-e. It is noteworthy that the mean by the self-registering maxima 

 and minima thermometers agree with that of the observed thermometers with- 

 in a trifle. The maximum was 68 on the 31st ; the minimum 33 on the 22nd. 

 The ivet-bulb thermometer mean, 44 "98 degrees, was -{■ 1 "86 above the average. 



Daily range of temperature mean, 17 '23 degrees, was -F 2"09 above the 

 average. The greatest range was on the 29th, being 28 degrees. These ex- 

 cessive changes of temperature, together with fresh winds and an excess of 

 ozone, caused much disease of the organs of respiration, principally catarrh, 

 but popularly, through erroneously, called influenza. 



Solar intensity xnB^n, 78'11 degrees, was + 260 above the average, which is 

 remarkable, as 'cloud mean was also considerably above the average. The 

 hottest sunshine was 94 degrees on the 31st. 



Terrestrial radiation mean, 35 '40 degrees, was — 15 below the average. 

 The lowest records were in the nights of the 22nd and 23rd, being 29 degrees. 



Elastic-force of vapour mean, 260, was -f 3 above the average. It ranged 

 from 175 on the 19th to 374 on the 14th. 



Humidity mean, 76, was — 7 below the average. Saturation (100) was 

 registered three times. 



Rain-fall &mowa.tc(\. to 3*59 inches, being -H 1"53 above the July average. 

 This is the first time since November, 1870, that the rainfall has attained the 

 average. It fell i a a gentle and continuous way, there being 18 wet days, or 

 -f- 4 '27 more than the average. No floods occurred in Hobart Town, at 

 the same time water courses, sewers, and rivulets were thoroughly flushed. 

 Snoio was never absent from Blount AVellington during tlie month, and re- 

 ceived frequent and copious augmentations. On the 19th the streets and 



