ON THE METEOROLOGY OF IRELAND. 325 



For further details of the plan of observation, the reader is 

 referred to the " Instructions" prepared by the Council of the 

 Academy. I now proceed to the results of the observations. 



TEMPERATURE OF THE AIR. 



Corrections. It has been already stated, that the thermometers 

 employed in measuring the temperature and humidity of the air 

 were carefully compared with a standard thermometer, and their 

 errors noted. When the errors differed by more than 0'2 in diffe- 

 rent parts of the scale, the instrument was rejected ; when they did 

 not, the mean of the observed errors was adopted as a constant 

 error for the whole scale of the instrument. 



It has been stated that the mean of the temperatures observed 

 at 9 A. M. and 9 P.M. is, very nearly, the mean of the entire day. 

 The small corrections required, in order to reduce the former to the 

 latter, are obtained from the bi-hourly observations of temperature 

 made at Dublin in the years 1840-1843. The following Table 

 contains the results of that series, and gives the mean differences 

 between the temperature at each hour of observation, and that of 

 the entire day : 



