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i-NALYSlS OF THE OBSERVATORY RECORDS FOR DECEMBER, 

 1865, IN CONJUNCTION WITH THOSE OF BIRTHS, DEATHS, 

 &c. By E. Swarbreck Hall. 



No December of tlie previous eight years had meteorological conditiong so 

 favorable to health and life as the present mouth presents la fact, for five 

 or six years past, the character of December weather has in raauy respects 

 altered for the better. The mean temperature has fallen lower, and th» 

 extremes have not been so great. Rain, particularly, has been more abundant. 

 By the Koyal-Observatory records for the 14 years, 1841 to 1854, the average 

 rain-fall in December was less than an iucli i.e., "92 of an inch, and the 

 wettest year of the whole, 1848, had only 2' o6 inches. In the succeeding six 

 years the mean rose to 1'73 inches, the maximum year, 1855, having a fall of 

 2 "73 inches ; while io the last five years, 1861 to 1865, the avex-age has risen 

 to all but 4 inches; the maximum, 1863, being 7 60 inches, the minimum, 1862, 

 173 inches The latter alone being close upon half an inch above the 20 

 years' mean of the adopted standard. The purity of the air, also, as indicated 

 by the ozonometer, has during the last four years, greatly exceeded the first 

 four years, 1857 to 183 » of the series of observations. IJy the mortiiary table 

 it will be seen that the present December had a mortality considerably less than 

 any of the previous eight years, and one third less than the average of the 

 whole. 



Atmospheric loressure ranged from the minimum, 29"068, on the 19th, to the 

 maximum, 30'] 51, on the 26th. The month's extreme range, therefore, was 

 I "083 inches, within seven days. So Iowa maximum has not been recorded 

 since 1854, or a lower minimum since the same year, except in 1863 when it 

 was noted 28,954. Four, out of the last nine years, had a smaller extreme range 

 for the month. The pressure mean for the "month was 29*662, which is — •112 

 less than the average of the 20 years' adopted standard. Thia is a lower mean 

 than rt;corded for any December since 185 ). The greatest movement of the 

 barometer in any 24 hours, was a rise of +'397 on the 25th ; and the greatest 

 fall, — "365 occurred on the 19th. There were only eight other days on which 

 the movements exceeded one-fifth of an inch. Such moderate and little 

 varied atmospheric pressure was favorable to health and life, and its preserva- 

 tive influence can be distinctly deduced from the mortuary records. 



Wind pressure had a total of 74 '63 lbs, which is— 14 "39 lbs less than the 

 mean of the previous eight years. Nevertheless, serial movement was almost 

 constant though never violent. The greatest force was 5'2l lbs pressure to the 

 square foot, and was noted only at the 7 a.m. observation of the 19th. There 

 were only nine observations recorded, " calm," being 4'86 less than the average 

 of the cahns for December. North-west was the prevailing wind, and largely- 

 above the average both in frequency and force. West and South were both 

 above in frequency, but below in force. South-ivest was slightly above the 

 average in frequency and force. South-east was below the average in number, 

 but slightly above it in force, North, North-east, and East were all considerably 

 below the mean in both respects. Wind movement on the whole, therefore, 

 was propitious to health, taking into consideration the fact so often before 

 noted, that many of the North-icest winds are really deflected Westerly ones. No 

 hot winds occurred in Hobart Town during the month. 



Temperature mean, 59,41 degrees, is— 2'66 degrees less than the December 

 average of 2J years. November had a mean only a few decimals less. December 

 la<t year, though, was slightly cooler, but with that exception there has not 

 been so cool a December since 1852, The mean of all the maxima, or high-day 

 temperatures, was 70.13 degrees, being nearly one degree and a half less than 

 for November. The maximum, 81 , occurred on the 27th, and is 14 degrees 

 below the November maximam. The mean of all the minima, or low-uight 

 temperatures, was 49.15 degrees, being rather more than one degree higher 

 than the corresponding records gave in the previous month. The minimum, 

 4;i, was registered for the night of the 3rd, and is four degrees above 

 November's minimum. The day maxima mean in Deceniber last year was 

 exactly the same as that of the present month, but the night minima mean 

 was more than four degrees warmer. The mean of both the self -registering 

 thermometers for the present month, was less than half a degree higher than 



