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Abstract of Paper on a Comparison of Observations at the Observatory and at the 



Public School, Fort- William. By R. T. Omond. # , , 



When the Observatory on the summit of Ben Nevis was opened in 1883, arrangements 

 were made with Mr Colin Livingston, of the Public School, Fort- William, whereby 

 observations were made five times a day at the Schoolhouse for comparison with those 

 on Ben Nevis. These observations, from December 1883 to December 1887, were 

 published in vol. xxxiv. of the Transactions R.S.E., along with the Ben Nevis records ; 

 and three years more, up to December 1890, are given in this volume (see Introduction, 

 p. 7). The Fort- William Observatory was opened in August 1890, but Mr Livingston 

 kindly continued his observations till the end of 1891, so as to allow of a comparison 

 between these two stations, which was the more desirable as Mr Livingston's 

 observations had been used for the original determinations of the differences of pressure 

 and temperature between Ben Nevis and sea-level, and any discrepancy between the 

 observations made at the Schoolhouse and at the Observatory would necessitate a 

 readjustment of these constants. 



The Observatory and Schoolhouse both stand facing the sea, with only a strip of 

 garden and the public road between them and the beach. They are distant from each 

 other about 150 yards ; the cistern of the barometer at the Observatory is 42 feet, and 

 at the Schoolhouse 33 feet above sea-level by Ordnance datum. There are two sets of 

 thermometers at the Observatory: the photographic thermograph in a large louvred 

 screen on the north wall of the building, and ordinary thermometers in a Stevenson 

 screen 12 yards from the nearest part of the building (see Introduction, p. 6). At the 

 Schoolhouse the thermometers were in a Stevenson screen on a grass plot at the back of 

 the house. Along the back of the grounds of both places runs a bank about 20 feet 

 high, above which the ground slopes upward into high moorland. The Observatory 

 thermometers and rain-gauges are fully 50 yards out from this bank, but at the School- 

 house they were nearer, — only some 5 yards from the beginning of the rise. In the 

 comparisons made in this paper the thermometers and barometers have been corrected 

 for instrumental error, and the latter reduced to 32° and sea-level. A table is given 

 showing the differences of the monthly averages from August 1890 to December 1891 

 (see p. 540). 



Temperature. — In the first part of the table the differences of the dry and wet 

 bulb temperatures and of the maximum and minimum are given. It will be seen that 

 the maximum is higher and the minimum lower throughout the year at the School- 



* See Journal of Scottish Meteorological Society, vol. x. p. 49. 

 ROY. SOC. TRANS EDIN. — VOL. XLII. 3 Z 



