Mean TemperatureofHie Air. The fol- 

 lowing algebraic formula, which correctly 

 represents the mean temperature for all 

 Europe, has been investigated by M. G. G. 

 Hallstroem. = mean temperature, n 

 = the ordinal number of the month for 

 which the temperature is to be calculated 

 (thus for April n = 4). (xf+xe) = 

 the mean temperature taken as the mean 

 of observations taken at 10 A.M. and P.M : 

 then v = (xf -}- x e) 0-33 + 0-41 sin 

 [(n - 1) 30 -f 124 8'J. In winter | 

 (x f -\- x e) = v very nearly, while in 

 summer this quantity is of a degree 

 greater than v at Paris, Halle, and Abo. 



Botany. A tree shoots out its branches 

 like all other trees of the same species, 

 external circumstances being similar ; but 

 there is one thing remarkable that has 

 not hitherto been noticed all trees with 

 spreading branches accommodate the di- 

 rection of the lower branches to the sur- 

 face of the earth over which they exfend. 

 This may be seen in orchards growing at 

 the sides of hills, arid all open forests. 

 This presents a curious fact for the inves- 

 tigation of the physiologist. The question 

 presented is this: What influence can 

 the earth have upon the branches on the 

 upper side of the tree, which causes them 

 to form a different angle with the body of 

 the tree, from the angle formed by the 

 branches on the lower side, so that all the 

 branches hold a parallel direction to the 

 earth's surface ? Mr. Knight's central 

 vessel hypothesis, and the authority of 

 numerous able physiologists, seem to be 

 at variance with the idea that the growth 

 of trees is not influenced by any circum- 

 stance connected with their internal woody 

 parts, but as the sugar maple (acer sac- 

 charinum), after being tapped and drained 

 of its internal sap fifty years, and, after 

 the whole interior has become dead, grows 

 as fast, and presents an aspect as vigorous 

 and blooming, as any sound tree of the 

 same species, and same age, which stands by 

 its side; and the common apple-tree (pyrus 

 malus) grows thriftily, and bears abun- 

 dance of fruit, many years after its inte- 

 rior is so completely rotted away, as to 

 leave but a very thin hollow cylinder in 

 possession of the living principle; and as 

 all depositions of matter, in any way af- 

 fecting the growth of the tree, are made 

 between the bark and wood, after the first 

 year, in the form of a mucilage, called 

 cambium, it seems that the internal woody 

 part has no influence upon the external 

 growth. We prefer solid trers in our 

 forests and orchards, because they have 

 more strength to withstand the force of 

 winds, and because the unfavourable cir- 

 cumstance which caused the interior to 

 decay may effect the total destruction of 

 the tree. 



To Increase the Odour of Roses. A 



Varieties. [JAN. 



German horticultural writer recommends 

 a large onion to be planted by the side of 

 the rose-tree, in such a manner that it shall 

 touch the foot of the latter. The roses 

 which will be produced will have an odour 

 much stronger and more agreeable than 

 such as have not been thus treated j and 

 the water distilled from these roses is 

 equally superior to that prepared by means 

 of ordinary rose leaves. 



Preparation of Blacking. Take of 

 plaister ground and sifted 2lbs. 4oz., lamp- 

 black about 9oz., barley malt, as used by 

 brewers, 18oz., olive oil loz. ; steep the 

 malt in water almost boiling hot until the 

 soluble portions are well extracted ; put 

 the solution into a basin, stir into it the 

 plaister and lampblack, and evaporate to 

 the consistency of paste , then add the eil, 

 the quantity of which may be increased 

 by degrees. To the mixture may be 

 added, if desired, a few drops of oil of 

 lemons, or of lavender, as a perfume. If 

 ground plaister be not attainable, its place 

 may be supplied with potter's clay. This, 

 which is the composition of a French che- 

 mist, M, Braconnot, is undoubtedly the 

 cheapest and finest blacking ; it spreads 

 evenly, dries and shines quickly on the 

 leather by a slight friction of the brush, 

 and has not the objection of burning the 

 leather. 



Destruction of Moles. The following 

 method of destroying these mischievous 

 little animals has been practised in France 

 with much success. A number of worms 

 must be procured, killed, and powdered 

 with pulverized vomica-nut; the whole is 

 to be mixt, and left for twenty-four hours. 

 The mole tracks are then to be opened, 

 and two or three of these worms placed in 

 each hole. If the meadow be large they 

 cannot be placed in every hole, but by 

 multiplying them as much as possible, a 

 good result is sure to be obtained. 



Powder Mills. Although great care is 

 taken to exclude from these manufactories 

 all articles of iron, and to substitute cop- 

 per and other metals in the metallic parts 

 of the machinery, which will not strike 

 fire, yet it is well know r n that explosions, 

 attended with disastrous consequences, 

 are very frequent. Excited by an occur- 

 reuce of this nature, Colonel Aubert, of 

 the French artillery, was induced, in con- 

 junction with Captain Tardy, to resume 

 some experiments which he had success- 

 fully tried to ascertain whether gunpow- 

 der would not explode by the shock of 

 copper. The result was, that powder 

 would inflame by the stroke of copper 

 upon copper, or upon the alloys of copper. 

 -This gave rise to further investigations in 

 presence of the Committee of Safety, and 

 it was ascertained that gunpowder could 

 be exploded by the stroke of iron upon 

 iron, iron upon copper, copper upon cop- 



