Miscellanies. 39 



o 



liistory of the weather as far back as our knowledge extends. If 

 the observations just related, with respect to a particular lot of timber 

 should be found to hold true of trees, in general, drawings of these 

 sections, on a reduced scale, would soon find their way to the pages 

 of scientific journals. It would be interesting, then, to make com- 

 parisons of one with another, — to compare the sections of one kind 

 of tree with that of another kind from the same locality, — or to com- 

 pare sections of the same kind of tree from different parts of the 

 country. Such a comparison would elicit a mass of facts, both with 

 respect to the progress of the seasons, and their relation to the growth 

 of timber, and might prove, hereafter, the means of carrying back 

 our knowledge of the seasons, through a period coeval with the age 

 of the oldest forest trees, and in regions of country where scientific 

 observation has never yet penetrated, nor a civilized population dwelt. 



7. Barometer. — We have lately received from Mr. Hudson, Sec- 

 retary and Librarian of the Royal Society, a series of " Experimen- 

 tal investigations on the Barometer," made by him, in order to de- 

 termine, if possible, the law T s which regulate its periodical changes 

 and to furnish data for explaining the anomalies of its daily and hour- 

 ly oscillations. The observations, amounting to three thousand in 

 number, were made during the months of April, May, June and 

 July, 1831, and January and February, 1832. To insure the great- 



est accuracy, the experiments were conducted with the most perfect 

 instruments, and with unexampled perseverance. For sixty days, 

 the observations were consecutive, through day and night, fifteen 

 times in each hour ; and the remainder were made for sixteen or 

 eighteen hours each day. 



It is weli known, that the periodical rise and fall of the barometer 

 is marked with great regularity in tropical climates, but the law which 

 prescribes and regulates those changes, has not been ascertained. 

 As we recede from the equator, to our own extra-tropical regions, 

 no constant law is apparent ; and the movements of the mercurial 

 column become irregular and violent. By examining, however, the 

 variations for several days, and classing the observations made at the 

 same hours on each successive day, and thus deriving from their union 

 the hours of one mean day, Mr. Hudson found that these accidental 

 variations neutralize each other — thus allowing the constant or equa- 

 torial oscillation to become appreciable. 



The following are some of the resuhs of Mr. Hudson's experi- 

 ments and observations. 



