EXPLANATION OF THE TABLES. 



The following tables, in continuation of those in the previous volumes, contain 

 meteorological observations made at the Ben Nevis and Fort AVilliam Observatories. 

 The hourly records of the Barometer, Dry and Wet Bulb Thermometers, Kainfall and 

 Sunshine at the two Observatories are printed side by side, those at Ben Nevis being 

 on the left and those at Fort William on the right-hand side. These four subjects 

 are placed first in each year's records, and following them are the hourly values of 

 Wind and of Amount of Cloud at the Ben Nevis Observatory, the Temperature 

 in a Stevenson Screen, Radiation Temperatures and Amount of Cloud at the Fort 

 William Observatory, Monthly and Annual Mean Hourly Values at the two Obser- 

 vatories, and the Log Book. 



The Barometer and Rainfall are recorded in inches, the Temperatures in degrees 

 Fahrenheit and the Sunshine in hours and decimal parts of an hour. The Wind Force 

 is on a modified Beaufort Scale of to 12, and the corresponding velocities in miles per 

 hour are given on page 5 of vol. xlii. The amount of Cloud is on the scale to 10, the 

 symbol = denoting fog or mist. All interpolated entries are enclosed in square brackets 

 and are included in computing the daily and hourly mean values. In the Barometer 

 and Temperature tables, the highest and lowest readings, and in the Rainfall and Sun- 

 shine tables, the highest only, are printed in bold-faced type. In this volume, the 

 hours of observation are Greenwich Mean Time, except in the Sunshine records which 

 are given in Local Mean Time. 



The Barometric readings at Fort William are reduced to 32° and Sea level, those at 

 Ben Nevis to 32° only. To save space the first figure of the Barometer entries is 

 omitted. At the Ben Nevis Observatory, where the pressure ranges from over 26 to 

 23 inches, the missing figure is always 2; e.g., 5*212 represents 25*212 inches, and 

 4*753 represents 24*753 inches. At the Fort William Observatory the whole inches 

 range from 31 to 27, and therefore when the figure before the decimal point in the 

 tables is 1 or the missing figure is 3, but when that figure is 9, 8, or 7, the missing 

 one is 2; e.g., 0*376 represents 30*376 ; 9*727 represents 29*727 ; and 8*618 represents 

 28*618 inches. 



A description of the instruments used at the two Observatories, of the methods of 

 observing, and fuller details of the records will be found in the introduction to the 

 previous volume of observations. See Transactions, vol. xlii., pp. 1-8. 



TRANS. ROY. SOC. EDIN. — VOL. XLIII. A 



