45 



ANALYSIS OF THE OBSERVATORY RECORDS FOR 

 MAY, 1866, IN CONJUNCTION WITH THOSE OF 

 BIRTHS, DEATHS, &c. Br E. Swarbreck Hall. 



Never before during the twenty-five years tliat exact and continuous mete- 

 orological records have been kept was there so warm a May as the present 

 mouth. Atmospheric pressure, too, was very high, calms very numerous, 

 with great predominance of winds from the quarter least favorable to health, 

 excessive daily ranges of tempciature, unusually hot sun, warm terrestrial 

 radiations, great elastic-force of vapour, and very peculiar electrical conditions. 

 At this season of the year all the pnenomeua alluded to were more or less ad- 

 verse to health and life. On the other hand, an average fall of rain, a slight 

 excess of atmospheric humidity, with ozone above the average, to some extent 

 counteracted the inimical phenomena, so that the mortuary return is not much 

 above the mean of the previous nine years for the month of May. May and 

 November have been always, on the average, the healthiest months in the year. 



Atmospheric pressure mean was 29 "932, being + '104 above the twenty years' 

 adopted standard mean. The maximum was o J. 389 on the Ist, the maxim.um 

 29354 on the 26th, so that the extreme range in the month was 1'035 inches. 

 The daily fluctuations were not excessive, the greatest range on any day being 

 a fall of —'480 of an inch on the 18th, and the smallest a fall of — "OlS of an 

 incli on the 7th. The greatest rise was + '366 of an inch on the 20th. Alto- 

 gether movements exceeding one-fifth of an inch were noted only on ten days, 

 and the maximum almost the same. 



Wind force, 55 "69 lbs, was + "5 12 above the May average of the previous 

 nine years, yet the calms (43) were -f- 3 '75 a1)0ve the average. Up to the 18th, 

 the wind pressure never exceeded '52 of a lb. pressure to the square foot, 

 and 26 calms were recorded. Strong winds from the south-west on the 18th and 

 19th, with equally strong north-west winds (a sort of abortive hot wind), on 

 the 25th, 26th, and 27th, raised the average greatly beyond what the general 

 character of the month would have made it. North-north-east and west were 

 all below the average both in frequency and force, south was below the 

 average in number but above it in strength, east and south-east were slightly 

 in excess, both in frequency and force, south-west winds though only slightly 

 more numerous than the average were -f 1713 lbs. above it in force, while 

 north-west with an excess of force of only -f- 3 "49 lbs, had no less than 51 in 

 number out of the 93 records, being +22 more than the average. On six days in 

 the month not a breath of wind was noted at the three hours of observ- 

 ation. 



Temperature me?in was 54 "20 degrees, being +3'69 degrees above the 20 

 years' standard mean, and -I- 4 "25 warmer than May 1865 was. No year of the 

 last 25 had so warm a May. The year next to it in warmth was 1856, when 

 the mean attained was 53'03 degrees. All the Mays of the last twelve years, 

 it is worthy of note, have much exceeded in their means, those of the pre- 

 vious fourteen years, the former having a mean of 51 '86, the latter only 49 "20 

 degrees. By the self-registeriug thermometers the mean was 5c "03 degrees, 

 the two sets of instruments approaching more nearly to the same result 

 than usual. The highest temperature recorded was 75 degrees on the 7th and 

 8th, and the lowest was 39 on the 17th. The mean of all the maxima or 

 high-day records was 63 71 degrees, being nearly one degree more than 1865 

 had. The mean of all the minima, or low ^ night records, was 46-35 degrees, 

 which is +3-83 above May, 1865. It thus appears that it was principally 

 by warmer nights, that the mean heat of the present month, so much 

 exceeded that of the corresponding month of 1865. 



Daily rancje of temperature mean, 17. 'do degrees, was -f 2. 05 degrees higher 

 than the 20 years' mean, though 2.59 less than May, 1865 had. The greatest 

 range on any day was 31 degrees, on the 7th ; and the least 3, on the 19th. 



The Solar-thermometer g&ve a. mean of 86.05 degrees, being -f4.18 degrees 

 above the mean of the previous 10 years, and +1.76 above May, 1865. The 

 maximum was 105 degrees, on the 7th, being one degree higher than last 

 year, but five more than was ever before recorded in the mouth of May ; 

 the minimum record was 56 degrees, ontheiyth. 



