374 



Institution, for another seven years. The observations should be 

 made wherever possible in an exposed spot ; and for a central 

 locality, neither too far up nor too low down the hill, none could 

 be better chosen than the open space in front of the Royal Crescent, 

 could it be made available for the purpose. The thermometer and 

 the wet-and-dry bulb would be the instruments alone required ; and 

 a single observation in the day, made always at the same hour, 

 9 a.m., and with tolerable regularity, would be sufficient. The only 

 important points to be attended to are, that the instruments before 

 being used be ascertained to be thoi'oughly trustworthy, that they 

 are so fixed as to be properly screened from all sources of eiTor, and 

 that the observer himself be very careful in noting down the 

 observations correctly. From neglecting these three precautions a 

 large nuniber of registers are worthless for all purposes of science. 



But the matter which I am more particularly anxious to bring 

 under your notice just now is the subject of rain-fall. No' part of 

 meteorology has of late years received more attention, or been more 

 closely inquired into by observers in this country than that which 

 relates to the " British Rainfall." This is mainly, if not entirely, 

 due to the zeal and activity of Mr. G. J. Symons, Secretary to a 

 Committee appointed several years back by the British Association 

 for the investigation of this subject. Mr. Symons has been the 

 means of getting raingauges to the number of nearly two thousand 

 set up in various parts of the British Islands, the same being 

 watched over by an " amateur staif of observers having no equal in 

 the world." A large number of these gauges are visited annually 

 by himself or others appointed by him, and the whole system of 

 observations is carried on under his directions. 



The question what is the mean annual rainfall in this country, as 

 also whether it has remained the same for as long a period baclc as 

 our observations reach, or whether the quantity that falls now is 

 greater or less than formerly ; these are questions which have 

 excited lately a good deal of interest from apprehensions in many 

 quarters caused by several remarkably dry seasons, that in conse- 

 quence of excessive sub-soil drainage and a too extensive felling of 

 timber, the average quantity of rain might be diminishing, and a 

 permanent deficiency of water for agricultural, manufacturing and 

 domestic purposes likely to foUow. 



