756 



UOCKlNti-STONKS 



ROCK-PLANTS 



KorkillK-stOlirs, or LOGANS, are large masses 

 of rxx'k no finely poised as to move backwards and 

 forwards with the slightest impulse. They occur 

 in nearly c\eiy coiiniiy. Some of them appear to 

 IM- Batumi, others artificial; the latter seem to 

 have been formed l>y culling iiwuy a mans of rock 

 round the centre-point of its iMkse. The former are 

 chiefly granitic rocks, in which felspar is abun- 

 dantly present; for, this mineral lieing readily 

 decomposed, the rock becomes disintegrated to 

 grit, sand, and dust, which are carried away by 

 rains and wind, so that what was formerly a solid 

 rock noon assumes the appearance of a group of 

 i i regularly -shaped pillars, separated into |>ortic>Ms 

 by horizontal and vertical fissures. As decay pro- 

 ceed*, the edges of the blocks forming the pillar 

 are first attacked and disappear, and the pillar 

 now Ittcomes a pile of two or more spheroidal rocks, 

 resting one upon the other. Should a mass of rock 

 lie so situated as to preserve it equilibrium in 

 spite of the gradual diminution of its base or point 

 of support, a rocking stone or logan is the result. 

 Although rocking stones are most frequently of 

 a granitic nature, they occur also among basalts 

 and other crystalline igneous masses. For the 

 principle regulating the stability of equilibrium of 

 rocking-stones, see STABILITY. Various explana- 

 tions have been given of the uses of these singular 

 objects. They are supposed to have been used in 

 very early times for purposes of divination, the 

 mother Of vibrations determining the oracle; hence 

 it came to be )>elieved that sanctity was acquired 

 by walking round them. 



Some rocking-stones occur near to remains of 

 ancient fortifications, which seems to bear out a 

 statement in one of the poems of Ossian, that the 

 bards walked round the stone singing, and made it 



move as an oracle of the fate of battle. In <; 



rocking-stones occur as funeral monuments, and are 

 generally found on conspicuous places near the sea. 

 Rocking" stones are numerous in Yorkshire, Derby- 

 shire, Cornwall, and Wales. The famous Logan 

 Rock, near Land's End, in Cornwall, is computed 

 to weigh over 70 tons. It was wantonly displaced 

 in 18-24 by Lieutenant Goldsmith, R.N., and his 

 boat's crew of nine men. He had to replace it at 

 a cost to himself of 2000 ; but whether it has 

 since rocked as well as ever is a moot point. Near 

 AYarton Crag, Lancashire, are no h than seven 

 of tlii'-c -tones : ami in Srol land tlie\ occur ill the 



Kucking-.itmiv of I Miilil. 



parishes of Kirkmichael, I iron, and Almrnethy, 

 Perthshire, and Kells, Kirkcudbrightshire. In 

 Ireland they are found in many places ; one situated 

 at a place called Islandmagee, on Hrown's Bay, 

 County Antrim, is jiopularly Ix'licvcd to acquire a 

 rocking tremulous motion at the approach of sinners 

 and malefactors. At Andafiord (Faroe Islands) a 

 large block of basalt, measuring some 16 feet in 



length by 10 feet in breadth, and rising for about 

 10 feet out of the water, swings to and fro with 

 the motion of the sea, which is alnmt seven fathoms 

 deep. All these, however, are as marbles com- 

 pared with the rocking-sUine of Tandil in the 

 .line Republic, -J.'id miles S. of Buenos Ayres, 

 for this weigns over 700 tuns, yet is so nicely 

 poised that it lock- in the wind, and may be mode 

 to crack a walnut. See Frank. Vincents Around 

 and About South America (1890), from which our 

 illustration is copied. 



Rock Island, capital of a county of that 

 name in Illinois, on the Mississippi, opposite 

 Davenport, Iowa (the two are connected by a 

 wrought-iron bridge which cost $1,300,000), Isl 

 miles by rail NVSW. of Chicago. The island from 

 which the town is named belongs to the United 

 States, and is used as a public park ; on it the 

 government has erected a great arsenal and armoury. 

 The channel to the east of the island has been 

 dammed so as to furnish immense water-power, 

 and the city 1m- flour and saw mills, besides 

 foundries, machine-shops, glass-works, &c. I'up. 

 (1880) 11,659; (1SHIO) 19,493. 



Rorkland, 1 1 ) capital of Knox county, Maine, 

 on the west side of Penobscot Bay, 88 miles by 

 rail ENE. of Portland. The Boston and liangor 

 steamboats touch here. The city bos granite 

 quarries, and many lime-kilns ; it ships a million 

 casks of lime yearly, and the New York post office 

 and St Louis custom-house are among the stiue- 

 lures built of its granite. Shipbuilding is carried 

 on, and there are iron and brass foundries, &c, 

 l'o|.. (1900)8100. (2) A town of M.i-surmi.-.-us, 111 

 miles by rail SSE. of Hoston, has larire manufacture* 

 ofbooU, sh and larks. Pop. ( HMMII .-,:fc>7. 



Rorklaild Lak", "<>ar the Hudson, 30 miles 

 N. of New N orU I'ily, i- :t miles in circumference, 

 and furnishes 200,000 tons of ice annually. 



Rockling (Onus), a genus of fishes of the Cod 

 family Cadidir, represented on the British coasts 

 by several species distinguished among other things 

 by the munber (3-5) of barlwls. The larger specie* 



Three-bearded Ruckling or Sea Loach. 



reach a length of 17 inches ; but none are of any 



\alnc as food, their flesh iu'i|uiriiig an unpleasant 

 -mell a lew hours after being taken out of the 



water. 



Rock-oil. See PETROLEUM. 



Rock-plants > n Gardening, a term applied to 

 a very miscellaneous group of plants, which by 

 I heir habit of growth are adapted to adorn rockertaa, 

 The plants are generally of lowly habit, either 

 tufted, creeping, or trailing. They may be shrubby 

 or herbaceous perennials, and certain annuals of 

 trailing habit are occasionally used for temporary 

 effect*. But the more restricted use of the term 

 comprehends merely the numerous species of 

 ALPINE PLANTS (q.v.) and such as resemble these 

 in their habit and adaptability to the purpose in 

 view the clothing of rock-work with verdure and 



