THE METEOROLOGY OF EDINBURGH. 73 



to Mr G. J. Symons, F.R.S., for copies of some of the earlier rainfall observations. 

 When no observations were available for the City, the Barnton register was utilised. 

 It is to be particularly observed that the process adopted of dovetailing one rainfall 

 record into the other introduces a slight element of error, the precipitation, as a 

 whole, increasing the nearer the station is to the high grounds surrounding Arthur's 

 Seat, the Blackford Hill, and the Pentlands (see Jour. Scot. Met. Soc, vol. x. p. 16). # 

 The records, however, approximate closely to the mean rainfall of Charlotte Square, as 

 shown by the observations taken there during the last forty-five years. 



The mean annual rainfall is 25'86 inches, the wettest year being 1872, with a rain- 

 fall of 38 '96 inches, and the driest, 1826 (the year of the short crop), with a downfall 

 of only 15 27 inches. These amounts are respectively 51 per cent, above, and 41 per 

 cent, below the mean. The wettest month is July ; the mean daily fall being - 091 

 inch, and the driest month March, the average being '049 inch. 



The wettest month was September 1785 with a rainfall of 10'69 inches, and the 

 driest March 1781 with a rainfall of 0'03 inch. The mean annual number of days with 

 001 inch or more of rain, taking the observations of the last twenty years (1877-96), is 

 190, distributed throughout the year as follows : — 



Jan. 



Feb. 



Mar. 



Apr. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



16 



14 



15 



14 



14 



14 



18 



19 



16 



17 



17 



1G 



The greatest number of days with rain in the period 1856-96 was twenty-nine in 

 July 1882, and the least, two for March 1856. 



Droughts and Heavy Rains. 



Since the year 1770, as already stated in last section, rainfall observations have been 

 taken in Edinburgh or its immediate vicinity without a break, there being always one 

 or more rain-gauges at work in different parts of the city. During thirty-four years, 

 however, viz., from 1777-79, 1781-83, 1817-23, and from 1833-55, the rainfall 

 measurements were only made weekly or monthly. Waterston for a year or two gave 

 the amounts recorded during great falls, but they have not been utilised. The 

 material available for examination in connection with this inquiry was thus restricted 

 to the ninety-two years during each of which the gauge was examined daily, and the 

 amount, if any, measured. The period under discussion ends with 1895. 



Before stating the more prominent results of an investigation into droughts it seems 

 desirable to give an answer to the question, " What is a drought ? " Mr Symons, our 

 greatest authority on rainfall matters, has solved the problem by dividing droughts 

 into two classes, viz.. absolute and partial. He defines the former as periods of more 

 than fourteen consecutive days absolutely without rain, and the latter as periods of more 

 than twenty-eight consecutive days, the aggregate rainfall of which does not exceed one- 

 hundredth of an inch per day. The examination has been confined in the present 



* The mean annual rainfall for the twenty-five years, 1866-90, at various places in Edinburgh was as follows : — 

 Charlotte Square, 26-71 inches ; Cumin Place, 3013 inches ; Blacket Place, 29'86 inches ; and Napier Road, 28-97 inches. 



