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but in some fragments which are 

 cylindrical and without any fur- 

 rows, it is double, or four inches. 

 The compression from the sur- 

 rounding loose sand, acting while 

 the tube was still softened from 

 the effects of the intense heat, has 

 evidently caused the creases or 

 furrows. Judging from the un- 

 compressed fragments, the measure 

 or bore of the lightning must have 

 been about one inch and a quarter. 

 At Paris, M. M. Hachette and 

 Beaudant succeeded in making 

 tubes, in most respect similar to 

 these fulgorites, by passing very 

 strong shocks of galvanism through 

 finely powdered glass: when salt 

 was added, so as to increase its 

 fusibility, the tubes were larger in 

 every dimension. They failed 

 both with powdered felspar and 

 quartz. One tube formed with 

 pounded glass, was very nearly an 

 inch long, namely, -982, and had 

 an internal diameter of -019. When 

 we hear that the strongest battery 

 in Paris was used, and that the 

 effect on a substance of such easy 

 fusibility as glass, was to form 

 tubes so diminutive, we must feel 

 greatly astonished at the power of 

 a shock of lightning, which, striking 

 the sand in several places, has 

 formed a cylinder, in one instance, 

 of at least thirty feet long, and 

 having an internal bore, where not 

 compressed, of full an inch and a 

 half; and this is in a material so ex- 

 traordinarily refractory as quartz !" 

 Specimens of vitreous sand tubes 

 or fulgorites are contained in the 

 Museum of the Geological Society, 

 and the fifth volume of the Society's 

 transactions contains an engraving 

 of them. 



FULI'GINOUS. (fuliginosua, (Lat.)/w- 

 ligineux,-eme, Fr. fulligin6so, It.) 

 Sooty ; dark ; smoky ; dusky ; of 

 the colour of soot. 



FU'LLER'S-EABTH. A marl of a close 

 texture, soft and unctuous, con- 



taining about 25 per cent, of alu- 

 mina. It derives ita name from 

 its being used by fullers to take 

 the grease out of cloth before they 

 apply soap. Any clay having its 

 particles of silica very fine, may be 

 considered as fuller's earth ; for it 

 is the alumina alone which acts 

 upon the cloth, on account of its 

 strong affinity for greasy substances. 



FUNGIA. A genus of stony, free poly- 

 pifers, simple, orbicular, or oblong; 

 convex and lamellated in the upper 

 part with an oblong central groove, 

 concave and rough beneath. Many 

 species have been identified. 



FU'NGIFORM. Having its termination 

 resembling the head of a fungus : 

 certain substances are occasionally 

 found of this shape, as calcareous 

 stalactites, &c. 



FU'NGUS. (Lat. fungus.'] One of 

 the orders of the class Cryptogamia, 

 according to the artificial system of 

 Linna3us. A mushroom; an ex- 

 crescence from trees or plants not 

 naturally belonging to them; any 

 morbid sponge-like excrescence. 



FD'NNEL-SHAPED. In botany, applied 

 to a monopetalous corolla, having 

 a conical border placed upon a tube. 

 A form which gradually increases 

 in thickness towards its apex, and 

 scooped out, or hollowed, at its 

 apical margin. 



FtfBCULA. (Lat.) A fork, a peculiar 

 formation of bone in birds, of a 

 fork-like shape. Thefurcula, com- 

 monly known as the merry-thought- 

 bone, is seldom wanting in birds. 

 It is in form like a Y, common to 

 both shoulders, and joined by its 

 point to the most prominent part 

 of the crista of the sternum, while 

 the other extremities are connected 

 to the humeral end of the clavicles, 

 and the point of the scapulae, where 

 these two bones are articulated with 

 each other, and with the os humeri. 

 The furcula serves to keep the wings 

 at a proper distance in flying, and 

 is strong and expanded in birds 



