OR, PLAIN TEACHING. 



361 



remarkably exemplified in the 

 Orkney and Shetland Isles, 

 where the Pentland Frith rushes 

 madly through its channel at the 

 speed of thirteen miles an hour, 

 bursting in thunder over the 

 rocks, or, with the resistless 

 force of a mighty drill, scooping 

 out their sides into caverns, cells, 

 and hollows, or, battling for ages 

 on one spot, beats out huge rifts 

 or channels, through which the 

 water flings its hissing waves in 

 sheets of drenching foam. The 

 storms habitual to these coasts, 

 have so battered and excavated 

 the adjacent rocks, that, in a 

 calm, they look like some ruined 

 city, or sea-Palmyra, rising from 

 the waste of waters. 



The variety of beaches,, variously consisting 

 of sand, shingles, pebbles, mud, &c, and some- 

 times varying from day to day, must strike the 

 attention of every contemplative visitor to the 

 sea-side. The nature of beach depends upon 

 that of the surrounding coasts, the soil that 

 prevails inland, and the rivers which, acting 

 upon it, bear its fragmentary matters down to 

 the shore. When these are deposited upon the 

 shore, the aspect of the beach is affected by the 

 direction of the wind, the force of the waves, 

 and the nature of the deposit. When breakers 

 prevail, the shores are generally covered with 

 coarse shingles, or large pebbles. The force of 

 the inward breaker is sufficient to throw in 

 largo stones, but the retiring breaker is not 

 powerful enough to remove them : the sand is 

 therefore borne away, and the pebbles alone 

 remain. With a change or cessation of wind, 

 the action of the waves is altered, and the 

 sands are deposited over the pebbles or shingles : 

 thus there is endless variation in the aspect of 

 a beach from day to day. 



Looking outward from the 

 shore, we see those glorious 

 structures, " the great ships of 

 the sea, come and go." How 

 wonderfully has their construc- 

 tion changed since the time' 

 when the heavy hulk, 455, with 

 her single sail slowly moved 

 along the coast, and when the 



1 



mariner, having nothing but the 

 stars to guide him, rarely ven- 

 tured out of sight of land. 



Now we see the trim-built 

 sloop, 18, or shallop, in the 

 rigging of which we recognise 

 is 



1184. 



that the main-sail, or large sail 

 behind, is attached to a gajff 

 above, and to a boom below. A 

 sloop of war is, however, a vessel 

 of a different class, rigged either 

 as a ship, brig, or schooner, and 

 usually carrying from eighteen 

 to thirty- two guns. 



An ordinary sloop differs from 

 a cutter, 19, in having a moveable 



19 



1185. 



bowsprit, which may be run in on 

 the deck, the bowsprit of the 



G 



