NAVIGATION. 



245 



all this vast apparatus safely, on the wings of the wind, 

 across immense seas. 



These majestic floating structures are the result of the 

 ingenuity and united labour of many hundred of hands, and 

 are composed of a great number of well-proportioned pieces 

 of timber, nicely fastened together by means of iron nails 

 and bolts, and rendered so tight with tow and pitch, that no 

 water can penetrate into any part. 



To give motion to these enormous machines, lofty pieces 

 of timber called masts, have been fixed upright in them ; 

 and sails of linen cloth are placed for the purpose of catch- 

 ing the wind, and receiving its propelling power. It has 

 been requisite also to add vast quantities of cordage and 

 tackling. Yet all these would be insufficient for the perfect 

 government and direction of the vessel, if there were not 

 fastened to the hinder part of it, by means of hinges and 

 hooks, a moveable piece of wood called the rudder, very 

 small in proportion to the whole machine, but the least in- 

 clination of which to either side is sufficient to give imme- 

 diately a different direction to the enormous mass ; so that 

 two men may direct and govern this floating town, with the 

 same or with greater ease than a single man can direct a 

 boat. 



Even the vaulted part of the fabric, together with its sharp 

 termination underneath, is proportioned according to the 

 nicest calculations ; and the length, width, and strength of 

 the sails and tackling, are all in due proportion to one ano- 

 ther, according to certain rules founded upon the principles 

 of the art of ship-building. 



A large -ship carries at least 2200 tons burden, that is, 

 '4,500,0001b., and at the same time is steered and governed 

 with as much ease as the smallest boat. And yet if such a 

 ship sailed along the coast only, and, like the navigators of 

 old, never lost sight of the shore, we might still look on 

 navigation as an easy business. But to find the shortest way 

 across an ocean from 4000 to 6000 miles in width, sailing by 

 day or by night, in fair weather or m foul, as well when the 

 sky is overcast, as vvhen it is clear, with no other guide than 

 the compass, or the height of the sun, the moon and stars, 

 with exactness and precision, is the extraordinary and surpris- 

 ing task of him who is skilled in the science oi n vibration. 



A violent storm of wind will raaice us tremlie 'i fear ill 

 21 * 



