FAHLUNIT1- 



i -' 



and massive. The primary form of the crystal it a cube, but the 

 regular tetrahedron U the predominating crystal. Colour steel-gray, 

 opaque. Lustre metallic. Specific gravity 4 -8 to 5'1 . Hardness S'O 

 to It), brittle. Cleavage parallel to the planea of the tetrahedron, 

 very indistinct Fracture conchoidal. 



Massive Variety. Amorphous. Structure granular to compact 

 It occurs in Cornwall. Hungary, Saxony, &c. A specimen from 

 Freiberg, analysed by Klaproth, yielded 



Arsenic .'..... 



Copper 

 Iron 

 Sulphur 

 Silver . 

 Loss 



2410 

 41-00 

 22-50 

 10-00 

 40 

 2-00 



-100 



It frequently contains a much larger quantity of silver, and not 

 uncommonly cine, 



Antiimmiiil Fahlore. It occurs crystallised in modified tetrahe- 

 drons. The colour dark lead-gray, approaching to iron-block, bjth 

 externally and internally : not very brittle. 



Analysis of a specimen from Kapuic by Klaproth : 



Antimony 22-00 



Coppsr 8775 



Iron 3-25 



Sulphur 28-00 



Silver, and a trace of Manganese . . '25 



Zinc 6-00 



Lou 3'75 



100 



FAHLUNITE, TrlMiuile, a. Mineral consisting of silicate of 

 alumina and other substances. It occurs crystallised and massive. 

 The primary form of the crystal U a right rhomboid prism, but it 

 usually occurs in imbedded, regular, hexagonal prisms. Colour 

 yellowish, greenish, and blackish-brown. Nearly or quite opaque. 

 Lustre resinous. Specific gravity 2'66. Hardness S'O to 5"5. Streak 

 grayish-white. Cleavage perpendicular to the axis of the prism. 



It is found at Fahlun in Sweden. 



Before the blow-pipe alone it becomes gray, aud fuses on its thinnest 

 edges ; with borax it melts slowly into a coloured glass. 



According to Kissinger it consists of 



Silica . ... 46-74 



Alumina . 

 Magnesia 

 Oxide of Iron 

 Oxide of Manganese 

 Water . 



26-73 

 2-97 

 6-11 

 0-43 



13-50 



-95-48 



FALCIFERI. [AMUOXITES.] 



FALCO. [FALCOSID.E.] 



FALCON. [FALCOSID.K.] 



FALC'ONID^E, Leach's name for a family of Raptorial Birds, or 

 birds of prey (Kaptores of llliger). In this family the destructive 

 power is considered by all zoologists to be most perfectly developed ; 

 and we find in the birds composing it natural instruments for striking, 

 trussing, and dissecting their prey, combined with a power of flight 

 and strength of limbs equivalent to the necessities of the case, whether 

 the prey be aerial, that is, whether it be the habit of the raptorial 

 liird in question to strike down its quarry while the latter is in the 

 act of flight, or whether the prey be terrestrial, or, in other words, 

 captured on the ground. Of these natural weapons some idea may be 

 funned from the cuts here given ; and they are rendered still more 



manner as those of the cat* [FEUD.K], which have the power of with- 

 (rawing or sheathing theirs within the integuments, but by a con- 

 urination which gives the bird of prey the power of elevating its 



claws at pleasure. The claws of falcons when sitting on stones or 

 arge branches of treea have often a cramped appearance ; but this 



arises in most instances from the care of the bird so to arrange 



talons that their points may not be blunted against the perch. 



Kill of the Peregrine Falcon (t'ulco ptrrgrinut), 



formidable by the organisation of the whole animal, which is calcu 

 lated to give them the greatest possible effect. The nails or claws, t< 

 be available, must be sharp ; and in order that they may be kept in 

 this state and fit for duty, there is a provision to enable the bird t> 

 prevent them from coming in contact with the ground or other foreign 

 hard bodies; for tbo claw 4 arc retractile, not indeed in the same 



Foot of the Peregrine Falcon (Fnlco ftrrfriitm). 



The power of flight, as Mr. Yarrell observes in his memoir ' On tho 

 Anatomy of Birds of Prey ' (' Zool. Jotini.,' vol. iii.), is one of the 

 decided marks of the distinct organisation of birds; and, as one divi- 

 sion of the first genus, Fnlco, appears to possess this power in the 

 highest degree of perfection, he proceeds to consider the conditions 

 necessary to produce such a degree. These, he observes, are large 

 and powerful pectoral muscles ; great extent of surface, as well as 

 peculiarity of form in the wing ; and feathers of firm texture, strong 

 in the shaft, with the filaments of the plume arranged and connected 

 to resist pressure from below. " A certain degree of specific gravity," 

 continues Mr. Yarrell, "is necessarily imparted by large pectoral 

 muscles, and the power of these muscles may be estimated by the 

 breadth of the sternum and the depth of its keel, as affording extent 

 of surface for the attachment of the large muscle by which the wing 

 is depressed. As an illustration of this form the breast-bone of the 

 Peregrine Falcon (Polto pereyriniu) is represented, which exhibit- t!m 



Breut-bone of the Peregrine Falcon reduced. 



a, the sternum; 6, the keel; r, the fuicula, or o rarcaloiiui; rf <l, the 

 clavicle* ; r t the scapula broken off. 



breadth of the sternum, tin: <li>|>th (if the keel, as well as the strength 

 of the clavicles ; and the power of (light peculiar to all the species of 

 true falcons is still further illustrated by the form aud substance of 

 the os furcatorius, which is circular, brood, and strong, affording a 

 permanent support to the shoulders. That the long and acuminated 

 form of the wing in the true falcons, with each feather narrow, firm 

 in consistence, the second the longest, and all gradually tapering to a 

 point, is also best adapted for rapidity of motion, may bo inf< n> 1 

 from the example in the various species of the genera Ifirutulo, Sco- 

 lopax, Tringa, Ckaratlriut, Proccllaria, Sterna, &c. ; but that extent 

 of surface and this peculiarity of form in the wing are not in them- 

 selves sufficient alone to afford rapid flight, is proved in the genus 

 /-arm, the speiU'S of which, though capable of exercising their 

 immense piniuns with graceful ease for hours in succession, without 

 any apparent lassitude, are still incapable of rapid flight, for want of 

 strong pectoral muscles. The numerous examples also furnished by 

 the Gallinaceous tribe sufficiently evince that immense pectoral 

 muscles are insufficient wln-n rc.upled with a small round wing, and 

 afford but a short flight, sustained with great labour, rapid in a small 

 proportion only to the strength and repetition of the impulse, and 

 accompanied by a vibration too well known to need further remark. 

 So material also is the perfection of the feather in the genus /'/<, 

 that when any of those of the wing or tail are broken, the flight of 

 the bird is so injured that falconers find it necessary to repair tin m. 

 For this purpose they are always provided with pinion and tail- 



