506 



DR BUCHAN ON THE 



carried out, and the results published in various papers that appeared chiefly in the Journal 

 of the Scottish Meteorological Society, the Annual Reports to the British Association, 

 and in Volumes I and II of the Ben Nevis Observations. Of the more important of these 

 discussions is the one dealing with the inter-relations of the hourly observations of 

 pressure, temperature, humidity, sunshine, cloud, winds, and rainfall, more particularly 

 as regards the bearings of the results on weather changes. The present paper forms 

 Part I of this large inquiry. 



The Reduction of the Ben Nevis Barometer to Sea-level. Table IV. 



A Table for reducing the barometric readings at Ben Nevis Observatory to sea-level 

 was given in the former volume of observations, and is reprinted with this Paper. The 

 Table was compiled by direct comparison of the observed barometric readings at the 

 Ben Nevis Observatory and at Fort- William, and consists of the difference between 

 these barometers, both being reduced to 32°, and the Fort- William one brought also to 

 sea-level. Any missing values were filled in by interpolation, and the whole smoothed 

 by cross averaging. A full description of the preparation of the Table will be found in 

 the first volume. (Transactions Royal Society, Edinburgh, vol. xxxiv. p. xxv.) 



The Table gives the corrections to be added to the Ben Nevis barometer to reduce 

 it to sea-level, arranged for each tenth of an inch of pressure and each degree of 

 temperature, and an interpolation Table is appended for the intermediate thousandths 

 of an inch and tenths of a degree Fahr. The differences between the successive lines 

 and columns of the main Table are so uniform that the same interpolations may be used 

 for all parts of the Table without introducing an error of more than one-thousandth of 

 an inch at any part. At the top of the main Table are given the temperatures, and at 

 the side the successive tenths of an inch of pressure, these temperatures being the mean 

 of the Ben Nevis and Fort- William temperatures, and these pressures the Fort- William 

 barometer readings at 32° and sea-level. In the interpolation Table the intermediate 

 thousandths of an inch are given at the top, and the tenths of a degree at the sides ; in 

 the body of this Table are the amounts to be added to or subtracted from the entries 

 in the main Table. 



Example — Wi June 1891, at Midnight. 



Fort-William barometer reduced to 32° and sea-level, 

 Ben Nevis barometer reduced to 32°, . 



Fort- William temperature, .... 



Ben Nevis temperature, ..... 



Mean temperature, ...... 



Correction in Table for 29 - 9 inches and 44 degrees, 

 Interpolation for 83 and '5, .... 



Correction for 29-983 and 44°-5, 



Ben Nevis Barometer reduced to sea-level, . 







29-983 







25-451 



49° 



•o 





40 c 



•o 





44 c 



•5 

 4-521 







+■ 9 







4-530 



4-530 





29-981 



