REV. R. F. WHEELER, M.A., AND DR. HOOPPELL. 497 



HUMIDITY. 



It is a matter for regret that there are so few observers of 

 humidity, considered as a separate branch of meteorology from 

 rainfall, in the district. The receipt of a greater number of 

 trustworthy observations of simultaneous readings of dry and 

 wet bulb thermometers would be highly esteemed. The obser- 

 vations require care in making, as errors in reading are very apt 

 to arise, and, though apparently small at the time, produce grave 

 discrepancies in the results. The instrument also requires fre- 

 quent attention. At the same time care and attention are all 

 that is required. The observations entail the expenditure of 

 but little time and labour, and are amongst the most valuable for 

 personal use at the time, as well as amongst the most useful for 

 scientific discussion at the year's end. 



The stations, from which the editors are able to give results 

 for the year 1871, are five : — North Sunderland, Eothbury, North 

 Shields, Durham, and Sedgefield. They have embodied them 

 in a general table. In this they have given the station, and hour, 

 at which the observations, upon which the results are based, 

 were made, the mean monthly reading of the dry bulb, the mean 

 monthly reading of the wet bulb, and the mean relative humidity. 

 By this latter term is meant the proportion of moisture, present 

 in the air, to the whole amount of moisture the air could have 

 contained, at its existing temperature, had it been saturated. 

 Those who are interested in this department of meteorology 

 can, from the data given, work out, by the aid of Grlaisher's 

 excellent hygrometrical tables, all other hygrometrical results 

 which they may desire. 



Subjoined is a subsidiary table, summarising the results em- 

 bodied in the general table, first, for the whole district, secondly, 

 for the whole year. 



g2 



