NOTES ON THE METEOROLOGY AND MORTALITY OF 

 THE MONTH OF SEPTEMBER, 1871, 



By E. Swarbueck Hall. 



With the excpption of June hist, this is the only month since August, 

 1870, in whicli the deaths have exceeded the average of the previous 13 

 and 14 years. 



The detailed remarks on the various meteorological phenomena of the 

 month will indicate siine of the causes to which this excessive mortality 

 may reasonably be ascribud. 



Atmuxphcric pressure mean, 2n'8r)G, was + '105 above the 25 years' 

 standiird mean for 8»'pteinber It ranged from minimum, 21) 18.") on the 

 7th, to ■iO;i(j'.> on the KJth, being an extreme rangi; for the month of 

 1"1S4 inches. The greatest movement of the barometer in any 24 hours 

 from I p.m. to 1 p.m., was .a fall of — •()82 of an inch on the 7th, being 

 the largest recorded durin,' the last 11 years. Ou 15 other days the 

 movements exceeded one-fifth of an inch, which is an unusually large 

 proportion for any month. 



Wind-force total »vas 42 23 lbs., being — 30 "30 less than the average 

 for this usually very win ly equinoctial month. The strongest winds were 

 only 5 21 lbs. pressure to the square foot; one Avas from the north-west 

 recorde 1 on the evenin,' of the 27th ; the other west at the morning 

 observation on the 9tli. At only five other observations was the pressure 

 of 2'60 lbs. registered. At 50 out of the 90 observations the wind blew 

 from the north-west, with 2211 lbs. of the total force. Fi'om north, 

 north-east, east, south-east, and south, only 23 winds were recorded with 

 the very small united force of 4 94 lbs. Calms vfQve 28 in number, being 

 -f 5*55 above the average. 



Temperafure mean, 54*22 degrees, was + 3*46 above the September 

 average. In the previous 30 years, only the Septembers of 1858 and 1855 

 were warmer than the jjresent month. The high-day mean was 63 23 

 degrees, the low-night 43*93 degrees. The maximum was 75 degrees, 

 noted on the 21st ; the minimum was 3.5, which occurred in the night of 

 the 6th. Wet-Bulb mean was 49*19 degrees, being + 2-62 above the 

 average. 



Daily -range of temperature mean, 19*30 degrees, was + 1*66 above the 

 average. The greatest was 32 degrees on the 21st. 



Solar intensity mean, 90*23 degrees, was 4- 1*69 above the average. 

 The liighest was 105 degrees recorded on the 18th and 21st. 



Terrestrial-radiation mean, 40*32 degrees, was -f 1'93 above the average. 

 The lowest was 31 degrees on the 6th. 



Elaafic-foi'ce of vapour mean, 298, was + 19 above the average, ranging 

 from 182 on the 6th, to 501 on the 18th. 



Humidity mean, 71, was — 5 below the average. 



Rain-fall amounted to 1 *60 inches, which is — "48 below the September 

 average. There were 16 days on which rain was registered, being + '73 

 above the usual number. On four days enough fell to scour the gutters 

 and drains, but not so heavily as to cause floods ; the rest was deposited 

 in light genial showers, keeping the ground in the most advantageous 

 state for vegetation. Snow was never absent from Mount Wellington 

 during the month, and received frequent and copious additions. 



Spontaneous-evaporation amounted to 3*10 inches. 



Cloud mean, 6*42, was + *58 above the average. 



Ozone mean, 8*35, was 4- *39 above the average. 



Saturation (10) was recorded 11 times. This excessive purity of the air, 

 together with excessive daily range of temperature and fi-equent variations 

 of atmospheric pressure, would account for the excessive number of 

 deaths. 



Electricity had 20 positives with tension from 4 to 9 ; and 34 negatives 

 with tension from 1 to 10, and 6 " nils." So high a tension has never be- 

 fore been recorded either from positive or negative. No thunder heard 

 or lightning seen duiing the month. Southern lights were seen on the 

 evening of the 3rd. 



