39 



ANALYSIS OF THE OBSEKVATOBY EECORDS FOR APRIL, 

 1865, IN CONJUNCTION WITH THOSE OF BIRTHS, DEATHS, 

 &c. By E. SwAEBEECK Hall. 



In many respects this April has had anomalous weather, nevertheless the 

 general result has been favorable to health and life, and more especially so 

 to infants under five years old, whose deaths were less than one-fifth of the 

 total at all ages. On the other hand, invalids, and particularly those of ad- 

 vanced age, have died in unusually large proportions; those at all ages 

 above 60, constituting rather more than one-third of the total of all ages. 



Atmospheric pressure mean, 29'951, was + "066 above the 20 years' average 

 for April, though less than either 1864 or 1863. The perturbations were both 

 frequent and extensive. The extremes were, 30"380, maximum, on the 23rd, 

 and 29 '456, minimum, on the 27th, being a range for the month of "924 of 

 an inch, but occurring within four days. The deaths on the three follow- 

 ing days amounted to 11, being by far the most fatal period of the month, 

 no other three consecutive days having more than five ; indeed, the first, 

 second, and fourth weeks had each only six deaths. The gi^eatest movement of 

 the barometer in any twenty-four hours, was a rise of + '510 of an inch on the 

 2nd, and the greatest fall was — "472 of an inch on the 26th. On thirteen 

 other days there were movements exceeding one-fifth of an inch. Extensive 

 and frequent changes in atmospheric pressure are always followed by the deaths 

 of many invalid and old persons, though children and healthy adults resist 

 its lethal influence wonderfully well. 



Wind /orce,-61*131bs., is -f 6*251bs. above the April mean in the four years* 

 computations contained in Mr. Abbott's 20 years' adopted standard tables, 

 while it is -i-16'25 more than that of the seven years now recorded. 

 This shows how necessary it is to obtain averages from a long series of records. 

 Sir John Herschell's statement of the periodical cycles of meteorological 

 phenomena makes it evident that nothing less than twenty years' records, can 

 give means entitled to much reliance in comparing annual deviations. North- 

 east, west, and north-west winds, were all above the average both in frequency 

 and force, and the other five points were all below. The north-west was the 

 predominant wind as indicated by the vane on St. David's Church, at the 

 three daily observations ; and yet there are other facts to prove, that the pre- 

 vailing winds were more westerly. It has been often shewn before, that the 

 peculiar conformation of the country to the west and north-west of this city, 

 gives a north-westerly deflection to westerly winds. In April last year the 

 total wind force was little more than one-third of that of the present month's 

 a very significant fact in connection with the much greater mortality April, 

 1864, had. The strongest winds in the present month had a pressure of 5 21 

 lbs. to the square foot, and were noted twice on the 11th, and once on the 

 13th. Calms were recorded 31 times, being only a few fractions beyond the 

 seven years' average for the month. 



Temperature mean, .56 "49°, is -fOO'85 higher than the 20 years' average, and 

 + "34 more than April last year had. The self-registering thermometers give a 

 much higher mean, 59"05°. The hottest day in this month, the 7th, is the 

 hottest day yet registered in 1865, being recorded 87 degrees. In only three 

 Aprils in the previous 24 years was a greater heat noted, i.e., 89 in 1860, 90 in 

 1856, 89 in 1855. This day had three deaths, while in all the previous six davs 

 of the month only as many occurred. The minimum temperature of the month 

 was, 38 degrees, on the nights of the 23rd and 25th. The month's range, 49 

 degrees, is greater than that of any April since 1857, when it was 50 degrees. 

 But I860 had the maximum range of the 24 years, being 60 degrees, the 

 extremes being 90 and 30. The mean of all the maxima of the self-registering 

 thermometer was 69 60 degrees. April, 1864, was only 64 -.50. The mean of aU 

 the minima records was 48 "50, that of 1804 being 48*63. It thus appears that 

 while the extreme night tempei-ature of the two months, was almost indentical, 

 the extreme day temperature of the present April was much gi-eater than last 

 year's. But the terrestrial radiation thermometers of the respective months 



