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XXII. 

 ON LIGHTHOUSES. 



You fishermen are acquainted with the great 

 value of lighthouses, as you navigate the stormy 

 seas. Indeed the erection of beacons, to mark 

 the situation of dangerous reefs and sands, was a 

 most important invention. This may be ob- 

 served more especially in passing along the 

 eastern coast of England. A tower, a flag-staff, 

 or a beacon ; some bearing a single light, some 

 double or triple ; some fixed, others revolving ; 

 of various colours and of various powers all 

 these are very ingenious, as well as beautiful 

 and useful contrivances, and enable an expe- 

 rienced pilot to ascertain his position on the 

 coast. But in foggy weather, as you must know, 

 lights will have a different colour from what 

 they have in a clear atmosphere. From this, and 



