508 MR OMOND ON THE 



this inquiry, as they were necessarily not simultaneous with any od the summit ; while 

 the weather in which Mr Mum's set was taken was not of an anti-c}^clonic character. 

 Mr Muir's readings, however, show that in ordinary weather the temperature half-way 

 up the hill is just midway between that of the summit and the base. 



There being thus no suitable intermediate observations at Ben Nevis, I examined 

 the Swiss mountain stations. There are no hourly observations at the Swiss hill 

 stations published except at Santis, but readings three times a day, at 7 a.m., 1 p.m., 

 and 9 p.m. are printed in extenso in the Annalen Schweiz Meteorolog., Zurich, for 

 twelve of the principal meteorological stations, including practically all the hill stations. 

 From these were selected Santis, 8202 feet; Pilatus, 6781 feet; Eigi, 5863 feet; and 

 Chaumont, 3700 feet, as hill stations; with Zurich, 1627 feet, and Altdorf, 1476 feet, 

 as base stations. The first three are true peaks ; Chaumont is on a broad-backed ridge 

 looking down on the Lake of Neuchatel, more than 2000 feet below it, while Zurich 

 and Altdorf, though not at sea-level, are at the base of the Swiss atmosphere, there 

 being no extent of lower ground near them. Thus we get between Santis and Zurich 

 a range of 6575 feet, with Pilatus and Rigi as intermediate stations at no great distance 

 away, and Chaumont farther to the west, but still useful for comparison. The readings 

 at 7 a.m. in winter give temperatures at the various stations but little influenced by 

 direct solar action, and therefore due mainly to terrestrial radiation and to the fluctua- 

 tions caused by weather changes. Tables have been drawn up showing the 7 a.m. 

 temperature at these six stations on each day for some months, with the differences 

 between several of the stations. From these tables it was easily seen which days had 

 large differences of temperature between hill and valley stations, and which little ; and 

 how, on such days, the temperatures at the intermediate stations compared with valley 

 and higher hill stations respectively. 



It is unnecessary to give such tables in full, but one typical case may be cited. 

 The greatest inversion of temperatures found in the two years' records yet examined is 

 from the 6th to the 9th inclusive of January 1893, when Switzerland was on the 

 western side of an anti-cyclone. On these four days the temperature at Zurich was 

 lower than on Santis, 6575 feet above it, not only at 7 a.m. but continuously all day, as 

 will be seen from the tri-daily readings in the table. 



From the differences between Santis and the other stations, it will be seen that 

 during these four days the great cold indicated by the readings at Zurich, and which 

 was felt to a greater or lesser extent at all the low-level stations in that part of Switzer- 

 land, was confined to a stratum of the atmosphere of no great vertical height. The air 

 immediately above this stratum was warm, and though Santis was throughout warmer 

 than Zurich, the intermediate stations were warmer than either, as will be seen by the 

 "Difference" columns. Pilatus, Rigi, and Chaumont were always warmer than Santis, 

 except at 7 a.m. on the 6th, when Chaumont was colder. Zurich, though always colder 

 than Santis, except at the very last reading — 9 p.m. on the 9th — was still further below 

 Rigi in temperature ; in fact, the vertical distribution of temperature among the hill 





