400 Scientific Intelligence — Miscellaneous, 



ing with its organization and character. The cod, the trout, and the 

 sturgeon, are found only in the north, and have no antarctic repre- 

 sentatives. The cactus is found only in America, and almost exclu- 

 sively in the tropical parts. Humboldt, to whom the earliest inves- 

 tigations on this subject are due, extends the principle not only to 

 the distribution of plants according to latitude, but also according to 

 vertical elevation above the surface of the earth in the same latitudes. 

 Thus an elevation of 14,000 feet under the tropics corresponds to 

 53° north latitude in America, and 68° in Europe. The vegetation 

 on the summit of Mount Etna would correspond with that of Mount 

 Washington, and this again with the summits of the Andes and the 

 level of the sea in the Arctic regions. In the ascent of a high moun- 

 tain, we have, as it were, a vertical section of the strata of vegeta- 

 tion which '• crop out," or successively appear, as we advance towards 

 the north over a wide extent of country. 



But in dwelling on the resemblances between the plants of high 

 latitudes and those of high mountains, we must not lose sight of their 

 not less constant differences. In the northern regions in general, 

 we find the number of species comparatively small. Thus, in the 

 region through which we have passed, and which has already a 

 northern character, we find vegetation characterized by great vigour ; 

 the whole country covered with trees and shrubs, and lichens and 

 mosses in great profusion, but the species few, and the proportion of 

 handsome flowering shrubs small. In the Alps, on the other hand, 

 vegetation is characterized by great beauty and variety, and the 

 number of brilliantly flowering plants, of Gentianaceae, Primulacese, 

 and Compositse, is very great. The plants, however, are dwarfish, 

 and vegetation comparatively scanty ; the lichens and mosses much 

 less abundant. There is, then, not an identity, but an analogy only, 

 and an imperfect though very interesting one, between Alpine and 

 Arctic vegetation.— ^^a55i^ on Lake Superior, p. 89. 



7. The Kirkwood Analogy, — -The following letter to Professor 

 Piazzi Smyth from Mr S. M. Drach of Hampstead, we insert as 

 received, deferring, from want of space, any observations on this im- 

 portant topic until a future opportunity : — 



" Dear Sir, — My attention having been directed to an article in 

 the last part of the Edinburgh New Philosophical Journal, signed 

 P. S., on Kirkwood's new presumed analogy of the planetary rota- 

 tions and limits of gravitating influence, I beg to refer to the London 

 * Philosophical Magazine' for January 1841, especially paragraph 

 5, page 40, wherein I shewed that the period of rotation of a primary 

 planet supposed to extend to the surface where its attraction — cen- 

 trifugal force — is precisely that of a satellite moving at the same dis- 

 tance as deduced from the actual satellites. There are several other 

 curious analogies in this paper which may possibly repay perusal. 



" By noticing this communication in the next number of the Edin- 

 burgh New Philosophical Journal, you will much oblige, yours truly, 



'' S. M. Drach. 



" To Professor Piazzi Smvth." 



