ovements--The Argand Lamp and Reflecting Mirrors--Revolving
Lights--The Catoptric System--Varieties of Lights--The Dioptric
System--Its Details--Introduction of this Method into Great
Britain--Comparison of the two Methods--The Drummond and Voltaic
Lights--Gurney's Lamp--Captain Basil Hall's Experiments--Ventilation
of Lighthouses 110

SMEATON AND LIGHTHOUSES.

CHAPTER I.

EARLY LIGHTHOUSES.

Origin of Lighthouses--Beacon Fires--Character of the Early
Watch-towers--Cressets--Colossus of Rhodes--The Pharos of
Alexandria--Epitome of Ancient Lighthouses--The Tour de
Corduan.

There is perhaps nothing better calculated to impress us with the
skill and ingenuity of man, and the power which scientific knowledge
imparts, than the sight of one of the beautiful Lighthouses of modern
times. Rising, it may be, from the point of a jutting rock amidst the
dashing and roaring of the breakers, it is exposed to the utmost fury
of the storm: graceful in its proportions, and uniting the elements of
security and beauty, it resists the terrific assaults of the winds and
waves, and bears aloft to the help of the tempest-tossed mariner, the
warning light that bids him shun the rocky shore. The skill now
attained in the construction of Lighthouses has been of slow and
difficult acquirement, the fruit of much patient and persevering toil,
and of many painful experiences: it will, therefore, be interesting to
trace the steps by which a result so important in the history of
commerce has been successfully achieved.

At a very early period it was customary to light up beacon-fires along
the most frequented coasts. These fires were kindled on the summits of
lofty towers, which served the double purpose of lighthouses, and
temples dedicated to the gods. Here sacrifices were offered to appease
the storm, and prayers were made for the safety of the mariner. Thus
these lighthouse-towers were invested with a sacred character: their
beacon-fires were said to be inextinguishable; their priests performed
the rites and practised the arts of divination, inquiring into the
success of a proposed voyage, and making votive offerings for past
deliverances.

Hence it may naturally be supposed, that within these watch-towers was
to be found most of the nautical knowledge of the time; that here were
deposited such observations on the heavenly bodies as were attainable
at