34 



moreover, were frequent and extensive. The greatest on any one day, was a 

 fall of — '517 of an inch, on tlie 13th, followed by a rise of + '429 on the 14th 

 a fall again next day of — '317 ; and another rise on the 16th of + -300. On 

 the 25th there was a sudden rise of + '515 of an inch. Altogether there 

 were fourteen clays out of the thirty, on which the movemeots of the baro- 

 meter, fron^ noon to noon, exceeded one-fifth of an inch. Atmospheric pressure, 

 therefore, this month, differed widely in its details, from that of March, and 

 the death records of both months show, that the latter was more injurious 

 than the former, in the proportion of 12 to 4, in diseases of the " brain and 

 nervous system," and the "organs of circulation." 



Wind-force had only an aggiegate of 21-84 lbs., which is — 26"331bs. less than 

 the mean of the previous seven years' Aprils, and nearly 20 per cent, less than that 

 of the previous minimum April, 18(jl. Only south-east winds exceeded the 

 average, both in frequency and force. East, south-west, west, and north-west, 

 were all numerically above the usual prevalence, but of so gentle a character 

 that the forceof each was much below the mean. North, north-east, and south 

 were all below the average both in frequency and force. The calms were 41, 

 being + 15 more than the average— 1861, however, had 44 calms — out of the 

 30 records at 7 a.m., calms were registered 21 times; at 1 p.m., 6 times ; at 

 sunset, 14 times. April last year had nearly double the wind force of the 

 pi'esent month. A stagnant condition of the air we breathe, is peculiarly 

 inimical to health, but it is a rare event in the breezy climate of Tasmania. 

 The strongest wind recorded during the month, had only 2*601bs. pressure to 

 the square foot : and was only noted five times. 



Temperature mean was, 56 "15 degrees, being + 'hi more than the 20 

 years' average, and + 1'38 degrees warmer than April, 1863 was. In the pre- 

 vious 23 years there were only six Aprils with a warmer mean. The maxima 

 and minima self-registering thermometers give a mean very little higher, 

 being 56 '56 degrees. The maximum, 77 degrees, was noted on the 1st ; the 

 minimum, 57, on the 30th. 



The daily ramje of temperature had a mean of only 15*81 degrees, which 

 is — 2*06 less than the 20 years' mean, and — 2 '34 below that of 1863. 

 The greatest range on any day, was 22 degrees, on the 1st, 12th, and 14th. 

 The minimum range was 8 degrees on the 9th and 10th. 



The solar-thermonneter mean was 95*00 degrees, which is -f 3*54 degrees above 

 the average of the previous 8 years, but +5 '89 degrees above April, 1863. 

 The maximum occurred on the 1st, and was 120 degrees, and was higher than 

 any of the pre^^ous 8 years had. Ten other days had a temperature above 

 loo degrees. The minimum was 64 degrees on the 9th. 



Terrestrial Radiation mean was 45*51 degrees, being -f-2"89 degi*ees above 

 the average, and almost the same above 1863. The maximum was 56 on the 

 4th, the minimum 32 on the 30th. 



Rain fell on 16 days of the month, being more numerous th^ in any April of 

 the previous 9 years, and exceeding the average of the whole, by -f- 4*4. It 

 also exceeded April last year by five days. The total of rain guaged was 2*18 

 inches, which is 4- *40 above the 20 years' average, but — *06 less than April, 

 1863 had — on only two of the 16 wet days was the rain precipitated vigorously 

 enough, to scour the street gutters, and conduce to health ; on the other 14 

 the effect of the deposit was thereby to moisten the surface, and with the other 

 concurrent meteorological phenomena, to promote decomposition and conse- 

 quently pollution of the atmospheric air. The first shower in the month {3rd) 

 was preceded by 17 days of continuous dry weather. This well exemplifies, 

 how much totals, and means, may mislead, in judging of the hygienic effects 

 of meteorological phenomena ; and .how necessary it is to scrutinize the daily 

 details, to be enabled to form satisfactory conclusions. Snow was seen abun- 

 dantly on Mount Wellington on the morning of the 25th, but no trace of it 

 could be seen on the following day. 



Spontaneous evaporation yf its ovUy 1*49 inches being less than that of any 

 April in the previous seven years. 



The mean Elastic force of Vapor was 376, being -t-52 above the mean of the 

 20 years. It is also the maximum of the 23 years, though the sickly April 

 of 1854 was nearly as high. 



Humidity mean, 82, was -f 6^ above the 20 years' standard. April 1847, 

 alone, out of the previous 23 years, was as high. For humidity and elastic 

 force of vapor to be both at the same time, above the average, is a most 

 unusual occurrence. The nile being, when humidity is high, for elastic-force 

 to be low, and the reverse when humidity is low. 



CZowd mean was 6*54, which is -i-*84 above the 20 years' average. There 

 liave only been four Api'ils more cloudy in the past 23 years. This is an unusual 



