NOTES ON THE METEOROLOGY AND MORTALITY OF 

 THE MONTH OF APRIL, 1871. 



By Dr. E. Swarbreck Hall, 



This month though unusually mild as to temperature, arid with great aerial 

 anovements, was characterised by high atmospheric pz'essure, wide daily 

 range of temperature, defective rain-fall, &,c. The deaths were much 

 below the average, and with a veiy ec^uable distribution as to age, but a most 

 unparalleled inequality of the sexes, females exceeding males in the propor- 

 tion of 16 to 12. 



Atmospheric pressure -mQ^in, 30*019, exceeded the 25 years' standard ave- 

 rage by -f 128. On ten days the variations exceeded one- fifth of an inch, 

 the maximum, a rise of + '040, having occurred on the 14th. Nevertheless the 

 range for the whole month was only '965 of an inch, the maximum being 

 SO -464 on the 21st, minimum, 29-499, on the 13th. 



Wind-force amounted in the aggregate to 73'381bs., being + 26 '70 above 

 the average. North-icest winds were recorded 51 times out of the 90, with 

 a force of 41'381bs. On fou.r days these winds partook of the character 

 of hot-icinds though in a subdued form. West winds were unusually frequent 

 and strong. On the 19th one was registered as exercising a pressure of 

 10'421bs. to the square foot, the maximum of the month. South-tcest to were 

 more numerous and stronger than common ; no South winds were recorded ; 

 South-east were only IS in number with a total of 4*941bs. force; no £ast 

 winds ; North-east 5 in number, only "TB of a lb. in force ; one North wind 

 •26 of a lb. strength. 



Temperature mean, 58*36 degrees, was +3 '33 above the April average. 

 The years 1855-6-7, only, out of the 30 years recorded, had a higher 

 mean. The maximum was 79 degrees on the 19th by the self -registering 

 thermometer, lent 80 by the observed thermometer at one p.m. There 

 was a strong hot-wind on that day. The April maximum has often been 

 higher than this. The minimum, 38, was recorded for the night of the 15th. 

 It has often been lower in ijrevious Aprils. The ivet bulb thermometer mean 

 was 52*11 degrees, being +1"02 above the average. 



Daily range of temperature me-ATi, 21*93 degrees, was +4*71 above the ave- 

 rage. The highest recorded was 32 degrees on the 2nd. 



Solar intensity mean, 90*32 degrees, was — 1*49 less than the average, 

 which may be accounted for by the excess of cloudy days. The maximum 

 ■was 115 degrees on the 2nd. 



Terrestrial radiation mean, 44.37 degrees, was — 1*30 above the average, the 

 minimum was 36 degrees in the night of the 16th. 



Elastic force ofvajyour mean, 323, was —2 less than the average ; it ranged 

 from minimum 215 in the morning of the 14th to maximum 545 at noon on 

 the 19th. 



Humidity mean, 67, was — 9 below the average. 



Rainfall amounted to only *86 of an inch, — 92 of an inch below the April 

 average — *62 of an inch fell in one day, the 13th. Only 4 wet days were re- 

 gistered, being —7*82 less than the average. Though almost all the me- 

 teorological phenomena of this month were widely different from those of 

 April, 1870, in no one was the contrast greater than in rainfall. In that 

 month there were 13 wet days with an aggregate amount of 4*25 inches. 

 Snow appeared on Mount Wellington on the 12th, 13th, and 14th. 



Spontaneous evaporation vf^iB 3*38 inches, a great excess over rainfall, as 

 was sure to be the case with so much wind and warmth. 



Cloud mean, 6*26, was + *52 above the average. 



Ozone, mean, 6*47, was —'52 only below the average. Saturation (10) was 

 registered on the mornings of the 14th and 25th. A much greater deficiency 

 of ozone might have been expected with such a prevalence of the anti-ozonic 

 winds from the north-west, and the very diy character of the month. 



Electricity was indicated by the ehctrometer for all the 60 observations 

 during the month, 12 of the records being "positive" -with tension from 4 to 

 7*5 ; the other 48 "negative" with tension from 2*5 to 7*5. 



Deaths.— OxAy 28 persons were registered as dying during this month, 

 though another is known of, but not yet registered as the law requires. The 



