454 Flonsoering of the Agave americdna 



itself; so that, were it not to make assurance doubly sure, the 

 stakes (in cases of comparative shelter) might be dispensed 

 with. 



Let us now examine the stability of a subject thus sup- 

 ported. 



When a tree is blown over, its roots are necessarily ele- 

 vated out of the soil on the one side at least, while the collar 

 must also have considerably changed its situation ; for the 

 axis of motion is at the lower side of the nucleus of roots, 

 perhaps 10 in. or 15 in. under the surface. The collar, there- 

 fore, must necessarily be moved to leeward; in short, describe 

 the arc of a circle corresponding in extent to its radial dis- 

 tance from the centre of motion. But, by the method of 

 propping now described, the collar is held immovable, and 

 the roots and soil feel the salutary restraint which the cross 

 imposes. In short, the tree may be bent or broken, but up- 

 rooted it cannot be whilst the materials keep their hold : and, 

 as there is no necessary limitation to the strength of the hori- 

 zontal cross, or number or extent of perpendicular stakes, 

 failure can be the result of awkwardness or miscalculation 

 oiily. 



And here I pause, confiding that I have accomplished the 

 great desideratum with which I set out ; that without in- 

 flicting any appreciable injury, or adhibiting any cumbrous 

 or unseemly appendage to the subject, or incommoding the 

 walk or park with guy ropes, I have shown (in this my last 

 method) the manner how to prop a tree, that will equally 

 resist the hissing of the critic and the howling of the gale. 

 In its principle, it is simple as truth ; in its operation, uni- 

 form as the law of gravitation ; and its efficiency, convincing 

 to the mind as the demonstrations of geometry. 



I am. Si)', yours, &c. 

 Annmi, Feb. 21. 1831. William Thom. 



Art. IX. Account of the Flowering of the Agave americana in 

 the United States. By J. M. of Philadelphia. 



In the London Magazine for July, 1764, there is an ac- 

 count of the flowering of an Agave americana, at Charleston, 

 South Carolina, in the year 1763. The plant was then 

 about twenty-eight years old ; the leaves 7 or 8 ft. long, and 

 proportionably broad and thick. On the 20th of April it 

 gave the first appearance of putting out to blossom, bursting 

 open the central leaves, about 6 ft. fi'om the ground. On 



