49 



ANALYSIS OF THE OBSERVATORY RECORDS FOR MAY, 1865, 

 IJSr CONJUrTCTION WITH THOSE OF BIRTHS, DEATHS, &o. 

 By E. Swaebreck Hall. 



The fluctuations in atmospheric pressure, with the frequent and extreme 

 rariations in temperature, this month, had an extensively fatal influence on 

 aged and diseased persons, and, together with the unusually numerous acci- 

 dental deaths, caused a total mortality slightly beyond tlie average of the 

 previous eight years, though, still, considerably fewer than May, 18G4, had. 

 On the other hand, the pure state uf the air, consequent upon its free move- 

 ment, the moderate rain-falls, and abundance of electricity, preserved the 

 community from Zymotic diseases ; and infantile deaths were not half the 

 number that May, 1864, had. 



Atmospheric pressure had a mean (29'820), so nearly that of the average of 

 the 20 years adopted standard, that it was only — '008 less ; nevertheless 

 the range, 1.503 inches, had never been neaily so great in May since 1865, 

 when it was 1"649. The maximum was recorded on the 23rd, being 30"3S8, 

 and the minimum 28 "885, happened on the 14th. The gi'eatest movement of 

 the barometer in any 24 hom's, was a fall of — "447 of an inch on the 27th. The 

 greatest rise was +'407 on the 15th ; and from that day the rises were great, 

 and continuous up to the 23rd. The 14th had a fall of — '401. Altogether there' 

 were variations of pressure exceeding one-fifth of an inch, on ten days in the 

 month. However, in comparison with May, 1864, this month's atmospherio 

 pressure was more favorable to life. 



Wind force had a total of 60'381bs., being +ll'041bs. above the May average 

 of the previous 8 years. S.W., N.W., and S. winds were above the average 

 both in frequency and force. East had a slight excess in force, but all the rest 

 were below the mean in both respects. The strongest winds had a pressure of 

 5 '2 libs, to the square foot, and were recorded six times. Calms were noted at 

 38 of the observations, being slightly below the average for May, 



Mean temiKrature, 49'95 degrees, was — 00*56 below the average for May, 

 and — 2*19 degrees less than May, 1864, bad. By the maxima and minima 

 self -registering thermometers, the mean deduced was 52 "65 degrees. The 

 difference between these two modes of ascertaining mean temperature is 

 unusually great. The hottest day of the month, the 11th, attained 71 degrees 

 of shade temperature, which is higher than any May of the tliree preceding 

 years. The coldest night was the 20th, when the thermometer marked 35 

 degrees. In 1864 the minima thermometer fell two degrees lower, and the 

 extreme range was one degree more. 



The daily range of temperature mean was 19'94 degrees, being + 4*64 

 degrees above the 20 years' average, and + 2 '78 higher than May last year. 

 Since 1857 no May has had a temperature so variable in its daily changes. 

 The greatest range in any 24 hours was 33 degrees on the 20th, and the lowest 

 was 8 degrees on the 26th May. 1857 had two degrees higher extreme range, 

 but no other of the 24 years recorded have been so high. European methcal 

 practitioners usually ascribe the variations in daily mortality (in the absence 

 of epidemic diseases) solely to fluctuations of temperature. An able article, in 

 the last number of the Popular Science Review, " On the Wave of Tempera- 

 ture, and the Wave of Death," adopts this view. Tasmanian experience how- 

 ever, does not confirm it. Possibly in our purer air, with the better feeding and 

 clothing of the great mass of the community, the constitution is more able to 

 resist the injurious influence of rapid changes of temperature. Even the very 

 young do not succumb to it j it is only the aged and diseased who sink under 

 it. 



Solar temperature mean, 84-29 degrees, was +2-68 degrees above the 

 average of the previous nine years, though one degree less than May 1864 had. 

 Nevertheless, as the present month exceeds last year's in its cloud mean, it 

 is evident that the sun while shining was hotter. Indee<l the maximum of 

 this mouth, 104, on the 10th, is four degrees above the highest in 1864, and is 

 the hottest on recoid in May. 



