390 Dr. Dal ton on the Theory of the Winds. 



hibit that perfectly transparent and colourless siliceous en- 

 velope; it is therefore proved by this circumstance that a great 

 mass of such siliceous envelopes might also be produced by 

 the decomposition of the -plants, or in the moist waj/ ; and also 

 that the mountain masses, which consist more or less of such si- 

 liceous envelopes, might not always be regarded as being pro- 

 duced by the action of heat at the bottom of the sea*. Bre- 

 bisson tries to bring the Diatomecc into two divisions, viz. the 

 proper Diatomece, which exhibit a siliceous envelope, and the 

 Desmidicc, which are without a siliceous coating and entirely 

 reduceable to carbon. In the more perfect plants, the epi- 

 dermis of which is penetrated by a siliceous envelope, it would 

 at least be improper to make such divisions ; in this case, how- 

 ever, they may be of some use. 



In a recent memoir Mohlf has again declared himself 

 against the animal nature of the Bacillarice. M I admit," says 

 he, " that the doubt which was raised respecting their vege- 

 table nature is not yet removed ; their animal nature however 

 has been as little proved, and we find evident transitions from 

 them to vegetables, &c. 



[To be continued.] 



XL1X. Notice relative to the Theory of the Winds. By John 

 Dalton, D.C.L., F.R.S. 



To Richard Taylor, Esq. 



Dear Friend, Manchester, Sept. 5th, 1837- 



1 PUBLISHED a theory of the Trade Winds, &c, as Mr. 

 ■*■ Dove has published:):, — it was forty-four years ago, as may 

 be seen in my Meteorology, 1793 and 1834<. It was first 

 published by G. Hadley, Esq., in 1735, as I afterwards learnt. 

 It is astonishing to find how the true theory should have stood 

 out so long. John Dalton. 



L. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



A LETTER addressed to C.Lyell,Esq. was then read from Dr. Mc 

 Cleland,who has been associated with Mr.Griffith in the scientific 

 deputation sent under Dr. Wallich into Upper Assam to investigate 

 the natural history of the country where the tea-plant is found growing 



* Ehrenberg's opinion is that these masses owe their origin to the action 

 of volcanic heat on the bottom of the sea. Vide Scientific Memoirs, vol. i. 

 p. 400.— W. F. 



t On the Symmetry of Plants. Tubingen, 1836, in December. (Published 

 as an Inaugural Dissertation.) 



J See our last and present Numbers. 



