Appendix F. MEAN" HEIGHT OF BAROMETER. 415 



quickened ; by either of which means nature would be enabled to 

 make up the deficiency. It is true that it is difficult to count one's 

 own respirations, but the average is considered in a healthy man to 

 be eighteen in a minute ; in my own case it is sixteen, an acceleration 

 of which by three or four could not have been overlooked, in the 

 repeated trials I made at Dorjiling, and still less the eight additional 

 inhalations required at 15,000 feet to make up for the deficiency of 

 oxygen in the air of that elevation. 



It has long been surmised that an alpine vegetation may owe some 

 of its peculiarities to the diminished atmospheric pressure ; and that 

 the latter being a condition which the gardener cannot supply, he can 

 never successfully cultivate such plants in general. I know of no 

 foundation for this hypothesis ; many plants, natives of the level of 

 the sea in other parts of the world, and some even of the hot plains 

 of Bengal, ascend to 12,000 and even 15,000 feet on the Himalaya, 

 unaffected by the diminished pressure. Any number of species from 

 low countries may be cultivated, and some have been for ages, at 

 10,000 to 14,000 feet without change. It is the same with the lower 

 animals ; innumerable instances may with ease be adduced of pressure 

 alone inducing no appreciable change, whilst there is absence of 

 proof to the contrary. The phenomena that accompany diminished 

 pressure are the real obstacles to the cultivation of alpine plants, of 

 which cold and the excessive climate are perhaps the most formidable. 

 Plants that grow in localities marked by sudden extremes of heat 

 and cold, are always very variable in stature, habit, and foliage. In 

 a state of nature we say the plants " accommodate themselves " to 

 these changes, and so they do within certain limits ; but for one that 

 survives of all the seeds that germinate in these inhospitable locali- 

 ties, thousands die. In our gardens we can neither imitate the 

 conditions of an alpine climate, nor offer others suited to the plants 

 of such climates. 



The mean height of the barometer at Mr. Hodgson's was 23-010, 

 but varied 0161 between July, when it was lowest, and October, 

 when it was highest ; following the monthly rise and fall of Calcutta 

 as to period, but not as to amount (or amplitude) ; for the mercury 

 at Calcutta stands in July upwards of half an inch (0555 Prinsep) 

 lower than it does in December. 



