33 



ANALYSIS OF THE OBSERVATORY RECORDS FOR 

 APRIL, 1866, IN CONJUNCTION WITH THOSE OF 

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



The meteorological phenomena tWs month have been so nicely balanced in 

 their influence upon health, that the death list is within a fraction of the 

 average of the previous nine years, though considerably higher, numerically, 

 than April 1865 was. 



Atmospheric pressure underwent no extensive perturbations, the greatest 

 movement of the barometer on any day did not exceed + "392 of an inch, 

 and the whole range of the month was only -843 of an inch, between the 

 4th, when the minimum, 29*609, occurred; and the 17th, when the maximum, 

 30-452, was registered. So high a minimum for this month was never before 

 noted in the 25 years' records. The mean pressure of the month was 30 '017, 

 which is + -132 above the 20 years' mean for April of the adopted standard- 

 tables, and + -066 more than 1865 had. Continuously high atmospheric pres- 

 sure is inimical to health, as well as sudden and wide fluctuations. 



Wind-force total, 56-46 lbs., is -I- I'SS above the 4 years' average in the 

 standard -tables, but + 778 more than the mean of the last nine years. It was, 

 however, very unequally distributed in the month. In the first and last five 

 days of the month no calms were recorded, and the winds were strong and 

 from favorable points of the compass. In these two periods the smallest num- 

 ber of deaths occurred, the first five days having only five deaths, and the 

 last five not a single one. So many days together without a death, is without 

 parallel hitherto in any month of any year recorded. On the other hand, 

 between the 6th and the 25th, there were no less than 35 calms noted out of 

 the 60 observations. The 14th, 15th, 16th, and 20th, had not an appreciable 

 amount of aerial mo'/ement at any one of the three daily observations. North- 

 east, south-east, south-west, west, and north-west winds were all above the 

 average in number, but only south-east and north-west had more than the 

 average force. The strongest winds recorded had a pressure of 5-21 lbs. to 

 the square foot, and were registered thrice in the first five days, and once in 

 the last five days of the month. There is no doubt that in the night of the 5th 

 inst. the strength of the wind must have attained 10-42 lbs. to the square 

 foot. The calms in the month, 35, exceeded the 4 years' table by -8-75, and 

 the average of the last eight years by -t- 4-50. 



Temiierature mean, 57*33 degrees, is + 1'69 above the 20 years' mean, and 

 nearly a degree warmer than April 1865 was. The mean by the self -register- 

 ing maxima and minima thermometers was 58-97 degrees, being about the 

 usual rate of difference with the observed thermometers. The mean of all 

 the maxima or high day temperatures was 68-87 degrees, being nearly one 

 degree less than 1865 had ; on the other hand the mean of all the minima 

 or low night temperatures was 49 07 degrees, which is rather more than half 

 a degree higher than April 1865 had. The highest day temperature was 

 97 degrees on the 10th, being 8 degrees less than the maximum last year. 

 The lowest night temperatuie, 38 degrees, on the 7th. Last year's was 

 exactly the same. 



Daily ravge of tenvperature had the mean of 19-80 degrees, which ia -f'88 

 degrees above the 20 years' mean for Apiil, but — -1-30 less than 1865 had. 

 The greatest range on any was 33 degrees on the 17th, and the lowest was 10 

 on the 25th. Last year the extremes were 38 and 4. 



The Solar-thermometer had a mean of 92-55 degrees, which is -f 2-37 de- 

 grees higher than the mean of the previous 10 years, and 4- 1-23 more than 

 1865 had. The maximum was 115 degrees on the 1st, the minimum ^60 on the 

 14th. Last year the extremes were respectively 120-5 and 64. 



Terrestrial-radiation mean was 47-25 degrees, being 4- 4-19 degrees above 

 fhe mean of the previous 10 years, and -f 3-07 more rhan April 1865 

 had. The maximum was 54 degrees in the nights of the 19th and 24th ; 

 the minimum was 36-5 in the night of the 7th, The extremes were much 

 wider in 1865, being 60 5 and 35. 



Rain fell in appreciable quantities only on 7 days of the month, being 

 ~- 4-82 days less than April average of the previous eleven years, and two less- 



