Mr Hewitt Watson's Barometrical Ohserr^atwns. 317 



riments made with four pair of half inch plates, mounted in 

 tubes, as Berzelius recommends, which, in decompositions, have 

 a decided advantage over eighty pair of four inch plates. 



110. Chakcert Laui:, 

 August 1832. 



Observations made during the Summer of 1832, on the Tem- 

 perature and Vegetation of the Scottish Highland Mountains^ 

 in connection with their Height above the Sea, By Hewitt 

 C. Watson, Esq. (Communicated by the Author *.) 



To a " Notice of Botanical excursions into the Highlands of 

 Scotland from Edinburgh'' last summer, written by Dr Graham, 

 and published in this Journal, are added some observations 

 made by myself on the relative altitudes at which the mountain 

 plants were found. At the time when those remarks were writ- 

 ten, other occupations prevented a more detailed account of the 

 altitudinal ranges of individual species ; nor would such have 

 altogether accorded with the object of Dr Graham's Notice. 

 But, as the tract of country passed over during that season, 

 included many of the highest hills of Scotland, observations 

 made on the range of absolute elevation within which particular 

 species were seen, as well as those on the temperature of the 

 air during the same period, must possess some interest to the 

 philosophic naturalist. The measurements of heights were all 

 made with Adie's Sympiesometer, the observations at the dif- 

 ferent stations being made in succession, not simultaneously ; 

 but by a repetition of those at the lower stations in returning 

 from the higher, and making due allowance for any variation 

 in the pressure of the atmosphere, no very important error 

 could occur. It may, however, be stated in general terms, that 

 these observations usually made the summits of the loftier hills 

 from 50 to 100 feet below their reputed heights. In using tlie 

 Sympiesometer, it is necessary to have it with its attached ther- 

 mometer in the shade. This circumstance caused me always to 



• The author of this interesting communication has lately printed, at the 

 office of Neill & Co., a valuable work entitled "Outlines of the Geographical 

 Distribution of British Plants, belonging to the Division of Vasculares or 

 Cotyledones. 8vo. 334 pages. For private dvttribution. 



