40 



shows that tho absolute night temperature of the present month was below 

 tliat of 1SG4, as will be seen hereafter. 



The daihj-ranye of temperature mean, was 21"10 cleg., being + 3"18 degrees 

 above the 20 years' average, ancH- 5"24 more than April, 18G4, had. The 

 greatest range for any day was 38 degrees, and noted on the 7th. No other 

 Ai)ril since 1857 has had so high a maximum, but in that year it attained 39 

 degrees, which is tlie maximum of the 24 years' records in Ai)ril. The minimum 

 variation was 10 degrees, and registered on the 4th and the 20th. 



The solar thermometer had ^ mefin of 91 '32 degrees, which is — '54 below 

 that of the 20 years, and — 3 08 less than April, 18G4, had. This is a puzzling 

 contrast, when the records shew the present mouth to be considerably less 

 cloudy than last yeai-, and at the same time the mean shade temperature of this 

 year, higher than tliat of 18(54. The maxinuim was 12i)r) on the 7th, which is 

 half-a-degree higher than Ai)ril, 18(54, had. However, while the highest of the 

 other nine records of 100 degrees or above, of the present mouth, only rose 

 to lOG degrees ; last year, out of ten, five exceeded that heat. The lowest of 

 the present month was the same as in 1864, i.e., 64 degrees 



Terrestrial radiation mean was 44 'IS degrees, being + 1*24 degrees more 

 than the average of the previous nine years, though -1 "33 degrees less than 

 April, 18(34,hafl. The extremes were 60 '5 on the 20th; 35 on the 25th ; while 

 those of 18(54 were 56 and 32. 



The rain fall this month was below the 20 years' average by more than 

 half-an-inch (i.e., '55), being altogether only 1"23 inches; while April, 1864, 

 had 2*18 inches. There were nine wet days, being — 3*10 belowthe average for 

 April of the previous ten years. On the 1st, 8th, and 26th enough of rain 

 was precipitated to flush the streets and drains, and the other days' showers, 

 together with the free serial movement, sufficed to maintain a. higher degree 

 of atmospheric purity than April, 1864, had. The snow that remained on 

 Mount Wellington on the last day of March, did not altogether disappear until 

 the 5th of the present month ; but there were no fresh dejjosits in April. 



Spontaneous evapoi'ation amounted to the same as the previous month, i.e.y 

 2-60 inches; 1864 had only 1-49. 



Elastic force of vapour mean, was 341, which, though + 17 more than the 

 20 years' average, was less than 1864 had by — 35 ; on the 6th, 7th, 20th, and 

 26th it was very high. 



Humiditii had a mean of 74, being — Ig below the 20 years' mean, and — 8 

 less than 1864 had. 



Cloud mean was 5 '72, which is almost identical with the 20 years' average 

 for April, though less by — '82 than April last year. 



Ozone mean, 8 '16, is + 1*32 above the mean of the previous eight years, 

 and higher than any one of them, exceeding last year by + 1*23. How effectu- 

 ally this atmospheric pui'ity protected the community from zymotic diseases 

 will be seen when the death records are analysed. On the 9th, 12th, 16th, and 

 28th, at 7 a.m. observation, the maximum of the chromatic scale 10 (satura- 

 tion) was recorded, and 6 was the lowest registered during the month. 



Electricity had 19 positive indications, with a maximum tension of 5*5, 

 and the lowest registered' 4, but the majority were at 5. In April last 

 year there were only 5 positive I'ecords witn maximum tension of 4. 

 Negative indications were 36 (6 less than 1864) with maximum tension of 

 4, but some falling as low as to 1. " Nil" was registered 5 times, i.e., at 

 the morning observation of the 1st; 5th, 8th, 19th, and 2l)th. No lightning 

 seen during the mouth, but thunder heard with the showers on the 8th. 

 All the collateral phenomense indicate that we were subjected on the 6th 

 and 7th, to the skirts of a hot wind prevailing on the Australian continent, 

 thovigh in Hobarton the wind on the 7th was registered, 7 a.m., N.W., 

 calm; 1p.m., N.E., •:26 of a pound pressui'e to the square foot ; sunset, W., 

 •52 of a pou.nd pressure. 



The 38 Deaths in the present month, contrast favorably with the eight 

 years preceding Aprils, as shown in the tables foUovsdng, for though 1862 had 

 one less death, yet both the infantile and zymotic deaths were more numer- 



