130 RAMBLES OP A NATURALIST. 



beacon heights discovered by the Greek prince when 

 he had wandered from his right course, and at which 

 he received the necessary instructions for finding his 

 way to his native country. According to the same 

 authorities, the solitary eyes of the Cyclops betoken 

 the fires lighted on the promontories of Sicily, while 

 the tradition which records that these giants expired 

 beneath the darts of Apollo, signifies merely that 

 these beacon lights, which were comparatively useless 

 through the day, were extinguished on the rising of 

 the sun. These buildings were frequently of very 

 considerable size ; indeed, the height of the Pharos 

 erected by Sostratus of Cnidos, on the low coast 

 of Alexandria, about 300 years before the Christian 

 era, very greatly exceeded that of any modern 

 lighthouse. 



This excessive elevation is, however, quite unne- 

 cessary for the attainment of the object proposed. 

 The difficulty in making a beacon-light visible from 

 a very remote distance does not consist in obtaining 

 any great degree of altitude, but in giving to the 

 light such an intensity as will enable it to traverse 

 a considerable space without being materially di- 

 minished. It was in this respect that the ancient 

 Phari, which were lighted by ordinary fires, were 

 especially defective, although they may perhaps have 

 been sufficiently powerful to aid the timorous sailors 

 of that age. When men acquired a profounder 

 knowledge of astronomy, and when the invention of 

 the mariner's compass opened all seas to navigation, 

 a number of the old beacons might perhaps be safely 

 dispensed with, although it would, at the same time, 



