rHiLosoriiv of stoums. 220 



cimens the world can produce, and amongst tliem arc the rarest that 

 have ever been found. 



Now, wishing to breathe fresh aii again, walk out into the garden. 

 You are fond of flowers. — You will there see numerous hot-houses, 

 which, if they were all put together, would reach further than eighteen 

 hundred feet, and in them you will find every tropical plant that can be 

 introduced and cultivated. There are more than sixteen thousand species 

 of plants in this garden, without counting the varieties ; and here you may 

 revel in botanical luxuries, if you happen to have any taste in that way. 



After promenading here for an hour or two, you will be ready to en- 

 ter another large building, and that is the Library. What a collection of 

 works on Natural History ! Thousands on thousands fill the well ap- 

 pointed shelves and cases. Here a student of Natural History could 

 spend his life, for whatever has been written on this subject, worth buy- 

 ing, is found in this Library. 



You may perhaps feel inclined to peep into the various lecture rooms, 

 and if it happens to be lecture hour, and there are few hours which are 

 not lecture hours, you will see crowds of studious young men hastily 

 scratching down into their portfolios the valuable instruction that falls 

 from the lips of the celebrated men, whom the enlightened government 

 of France has placed in those chairs. 



A mere cursoiy glance at the scientific riches of the garden of plants 

 will convince any one of fhe truth of Cuvier's declaration at the head of 

 this paper, "that it is the largest establishment that has ever been conse- 

 crated to the science of nature." M. 



PHILOSOPHY OF STORMS. NO. VH. 



BY PROF. W. L. ATLEE, M. D., PHILADELPHIA, PA. 



During a hot day when the dew point is very high and the uppei* 

 and lower currents of air are calm, the steam power in the air is very 

 great, and the up-moving, cloud forming column goes up to an immense 

 perpendicular height. The action of the column now becomes extreme- 

 ly violent in consequence of the cloud becoming very lofty at its top 

 and of great depth, and thus so much vapor will be condensed, and so 

 large an amount of caloric of elasticity evolved, that the cloud will ra- 

 pidly assume a specific gravity much inferior to that of the surround- 

 ing air. 



In this state of things, the air, which is pressed in on all sides be- 

 low, coming in beneath the cloud, will expand by diminished pressure 

 even before it ascends, and in expanding will become colder about five 



