40 SCIENTIFIC SOCIETIES. 



to their influence — the number of skeletons seen lying about the valley, bleached 

 to the whiteness of ivory — go far to furnish foundation for a dreadful tale : and 

 such are the actual scenes visited and described by Mr. Loudon. This gentleman 

 is inclined to impute the poisonous nature of the air in the valley rather to veget- 

 able miasmata than to the emission of carbonic acid gas from the ground. Col. 

 Sykes is of a different opinion, and assigned his reasons. 

 HORTICULTURAL SOCIETY. 

 Amongst the plants exhibited at a meeting of this Society, of the 7th of March, 

 were the following :— Splendid specimens of Dendrobium fimbriatum D. Pie?-adi, 

 and D. pitlckellum, from Messrs. Loddiges ; a new species of Callistemon, from 

 W. Harrison, Esq. ; Ipomsea Horsfallice, &c, from Mrs. Lawrence ; Andro- 

 meda floribunda, &c, from Mr. Glenny ; and a Rhododendron Russellianum, from 

 Mr. Gaines. Messrs. Loddiges obtained the Society's large silver medal, and 

 the other exhibitors respectively the silver Knightian medal. Many other beauti- 

 ful plants were exhibited ; and the usual distribution of grafts of esteemed and new 

 varieties of fruit took place. — The following is the statement of the extreme con- 

 ditions of the barometer and thermometer, and the amount of rain observed in the 

 Society's garden since the 21st of February : — 



Barom. Highest, March 1 30.431. 



Lowest, Feb. 23 29.324. 



Therraom. Highest, Feb. 21 54° Fahr. 



Lowest, Feb. 25 28° 



Total amount of rain 0.21 in. 



LINNiEAN SOCIETY. 

 Feb. 21. — A. B. Lambert, Esq., V.P. in the chair. — Mr. Iliff exhibited part 

 of an Oak tree, which had been blown down during the late hurricane at Wind- 

 sor Forest, and which, upon being split, was found to be carved in the interior 

 with the letters " W. B. 16'70." This singular circumstance was ascribed to the 

 growth of a new layer of alburnum in the part where the old wood had been cut 

 out, which was subsequently formed into wood. The Chairman exhibited the 

 leaves and flowers of a new species of Tamarisk, collected by Lieutenant Well- 

 sted in Mount Sinai. The Secretary read a communication from Lieutenant 

 W. on the Manna, Dragon's-blood, and Socotrine Aloe of Commerce. The author 

 found the true Manna tree, Tamariscus mannifera, growing plentifully in 

 Egypt, Nubia, and Mount Sinai, but only yielding manna in the latter locality ; 

 from which circumstance, as well as from its being produced by various vegetables, 

 as several species of Oak, Fraxinus, and the shrub Gavan, he concludes that it is 

 not a vegetable educt, but the deposition of an insect of the genus Coccus. It is 

 collected by the natives early in the morning, and about 700 lb. weight is gene- 

 rally procured during one season. The tree which yields the Dragon's-blood 

 (Sanguis draconis) grows on limestone rocks to the height of eighteen feet, and 



