. 766 



THE STANDARD DICTIONARY ( >1 FACTS 



other marine animals, and seem to care little 

 whether their prey be living or dead. They 

 often follow vessels for the sake of picking up 

 any offal which may he thrown overboard, and 

 man himself often becomes a victim to their 

 rapacity. The sharks are now divided into 

 several families, as the Carcharidsp, or white 

 sharks; Laminda?, or basking sharks; Scym- 

 nidae, including the Greenland shark; Scylliihi-. 

 or dog-fishes; etc. The basking shark is by far 

 the largest species, sometimes attaining the 

 length of forty feet, but it has none of the ferocity 

 of the others. The white shark is one of the 

 most formidable and voracious of the species. 

 It is rare on the British coasts, but common in 

 many of the warmer seas, reaching a length of 

 over thirty feet. The hammer-headed sharks 

 which are chiefly found in tropical seas, are very 

 voracious, and often attack man. They are 

 noteworthy for the remarkable shape of their 

 head, which resembles somewhat a double- 

 headed hammer, the eyes being at the extremi- 

 ties. Other forms are the porbeagle, blue shark, 

 fox shark, sea-fox, sea-ape, or thresher, and 

 Greenland or northern shark. 



Sheep, the common name of the genus Ovis, 

 belonging to the hollow-horned ruminant family. 

 Naturalists are by no means agreed as to what 

 was the original breed of this invaluable animal, 

 which is in modern farming almost equally 

 important for furnishing the farm with a dressing 

 of manure, and the community at large with 

 mutton, clothing and other necessaries of life. 

 The leading fact in the geographical history of 

 this genus is that it occurs both in the New and 

 the Old World, whereas the goat tribe are nat- 

 urally unknown in America. It is usually re- 

 garded by naturalists as being not only specifi- 

 cally, but generically, distinguished from the 

 goat tribe; but some authorities, on the other 

 hand, are inclined to .believe that the generic 

 separation is founded chiefly on characters which 

 have arisen from the influential power of man. 

 In a state of nature, the sheep is scarcely less 

 active or energetic than the goat ; its dimensions 

 are greater, its muscular strength at least equal 

 both in force and duration. It is also an Alpine 

 animal, and among its native fastnesses bounds 

 from rock to rock with almost inconceivable 

 swiftness and agility. The four unsubdued 

 races of sheep are as follows: The Musmon, the 

 bearded sheep of Africa; the Argali, or wild 

 sheep of Asia; and the Rocky Mountain sheep 

 of the United States. The latter is larger than 

 the largest varieties of domestic breegfs. The 

 horns of the male are of great dimensions, 

 arising a short way above the eyes, and occu- 

 pying almost the entire space between the ears, 

 but without touching each other at their bases. 

 The hair in this species resembles that of a deer, 

 and is short, dry, and flexible in its autumn 

 growth ; but becomes coarse, dry, and brittle as 

 the winter advances. The most important 

 breed of sheep as regards the texture of the, wool 

 is the Merino, in modern times brought to the 

 greatest perfection in Spain, through their 

 originals probably formed the flocks of the patri- 

 archs thousands of years ago, and have been the 

 stock of all the fine-wooled sheep. They readily 

 form cross breeds, called derm-merinos, which 



have been brought to great perfection in France, 

 whence, as well as from Spain, they have been 

 imported into the United States. 



Silkworm, a term applied to the larva-, or 

 caterpillars, of numerous species of moths. 1 he 

 common .silkworm moth is the most important 

 of the silk-producing moths, and is a native of 

 China , where it has been cultivated from a remote 

 period. The caterpillar (.s//A;/ww) is of yellow- 

 ish-grey color, and when full-grown is about 

 three inches in length, with a horn-like projection 

 on the last joint of the body. It feeds upon the 

 white mulberry, and will also eat the black 

 mulberry and lettuce, but the silk produced by 

 larvae fed on the latter is of an inferior quality. 

 The silk is produced in a pair of specially-con- 

 structed vessels which contain a gelatinous sub- 

 stance, and become much enlarged at the time 

 when the animal is about to spin. These silk- 

 organs unite at the mouth to form a common 

 duct termed the spinneret; and through this tube 

 the semi-fluid substance is ejected, and on coming 

 in contact with the air hardens into the soft 

 fiber which is so largely used in commerce. The 

 caterpillar employs the silk in constructing a 

 cocoon in which it assumes the pupa state. The 

 pupa is usually killed by plunging the cocoon 

 into hot water, because the natural exit of the 

 moth is injurious to the silk. The color of the 

 silk varies from a bright orange to almost white. 

 In Europe some moths produce one generation, 

 others two generations annually; but the cater- 

 pillars from the former class produce the best 

 silk. In India some forms produce eggs monthly 

 while three or four generations annually are not 

 uncommon in that country. A valued variety 

 is the Novi race of Italy, which spins a large 

 white oval cocoon. The Japanese race produces 

 a cocoon having a divided appearance in the 

 center. The Japanese oak-feeding silk-moth, 

 produces a green cocoon, the silk of which is 

 much used for embroidery. Another species 

 inhabits Northern China and is also an oak- 

 feeder. Its cocoon is large and grayish-brown 

 in color. The B. Cynthia of China and North 

 Asia manufactures a gray cocoon, from which 

 the Chinese manufacture a silk recognized by its 

 soft texture. From the cocoon of the Indian or 

 "tussur moth," the natives manufacture the 

 Tussur silk fabric. Bombyx textor of Bengal 

 makes a pure white silk used by the natives. 

 There are several other varieties of silk-pro- 

 ducing moths, but they are less notable and com- 

 mercially unimportant. 



Silver, a brilliant white metal which was 

 known to the ancients. It crystallizes in cubes. 

 It melts at a heat estimated at about 1,000. 

 When melted, it absorbs oxygen, and just before 

 solidifying it evolves it w r ith effervescence, 

 causing spiriting and projection of the metal. 

 It is the best known conductor of electricity and 

 heat; is extremely malleable and ductile, and 

 has great tenacity; it is not oxidized at the 

 ordinary temperature, and is unaffected by any 

 atmospheric agent, except sulphur compounds 

 which are sometimes present. It is found either 

 in the native state or as sulphide or chloride. It 

 also occurs in small quantities in galena, gray 

 copper ore, pyrites, and other minerals, and 

 frequently in sufficient quantity to pay for 



