218 



J. HOPKINSON METEOROLOGICAL OBSEBVATI0X3 



the instrument is about 272 feet above Ordnance Datum. The 

 readings are first entered without any correction, but the monthly- 

 means and other readings here given are corrected for index error 

 and capiUarity, reduced to 32° in accordance with the readings of 

 the attached thermometer (No. 39031), and to sea-level, taking 

 into account the temperature of the external air. 



The thermometers consist of a Negretti maximum, a Euthcrford 

 minimum, and a dry- and wet-bulb, or hygrometer. They are 

 placed in a Stevenson screen, over grass, and at a considerable 

 distance from any wall or building. Their bulbs are about four 

 feet above the ground. Their readings are corrected for index 

 errors only. The dry- and wet-bulb thermometers are practically 

 correct, their maximum error, O'^'l, being too slight to necessitate 

 a correction being made. The maximum requires a slight correc- 

 tion when at or above 62°, and the minimum when as low as 

 12°. The following are the precise coiTections : — 



Minimum. 

 (No. 39076.) 



Maximum. 

 (No. 39077.) 



Dry-Bulb. 



(No. 39078.) 



"Wet-bulb. 

 (No. 39079.) 



At 12° +0°-3 



22° -fo -1 



32° -0 



42° -0 



62° -0 



62° -0 



72° — -1 



At 32° 0°0 



42° -f -1 



62° -0 



62^ +0 -2 



72° -\-0 -2 



82° -1-0 -2 



92° -j-0 -2 



At 32° 0°-0 



42° -0 



52° -0 



62° -0 



72° -\-0 -1 



82° -0 



92° — -1 



At 32° 0°-0 



42° -0 



52° -0 



62° — -1 



72° -0 



82° -0 



92° — -1 



The rain gauge used during the year 1876 is a "Howard," by 

 R. and J. Beck. From the commencement of the year 1877 a 

 " Snowdon " gauge, by J. J. Hicks, has been used for the diiily 

 observations, and the Howard has been read weekly and at the 

 end of each month, as a check upon the daily readings of the 

 Snowdon gauge. Both gauges are five inches in diameter. The 

 Howard has not been verified, the Snowdon (No. 103) has, and 

 is correct throughout the scale. They are placed about two feet 

 from each other, with their rims one foot above the ground. Their 

 exposure is very open, no trees or buildings being near. 



The rain gauges are read at 9 a.m., and the amounts entered to 

 the previous day (or Aveek);'the maximum and minimum thermo- 

 meters are read at 9 p.m., and entered to the same day ; and the 

 other instruments are read at both 9 a.m. and 9 p.m., when the 

 direction and force of the wind (estimated), and the amount of 

 cloud, or proportion of sky covered by cloud, are also entered. 



The accompanying table gives the monthly means of these 

 observations, and of other results deduced from them. The 

 direction of the wind is given entirely from the morning observa- 

 tions, as I have frequently been uncertain as to its direction at 

 night. For the first three months also the dry- and wet-bulb 

 thermometers were not read at 9 p.m., nor were the amount of 



