90 PHYSICAL GEOGRAPHY OF THE SIA. 
reckoned among the seven wonders of the world, and its several 
stories, rising on marble columns to the height of 400 feet, 
must have presented an imposing spectacle, but I strongly 
suspect that the rude brazier on the summit of the majestic 
pile bore the same proportion to the lighthouse Janterns of our 
time as the wretched coasting-craft of the ancient Greeks to the 
ocean steamers of the present day. Among the names of those 
who have contributed most effectually to the progress of marine 
illumination Argand, Borda, and Fresnel are conspicuous. The 
hollow cylindrical wick of the first was a sudden and immense ad- 
vance in the art of economical and effective illumination. The 
second, by his invention of tle parabolic mirror, multiplied the 
effect of the unassisted flame by 450, and the refracting lens of 
Fresnel so admirably concentrates the light as to project its warn- 
ing beams to the wonderful distance of thirty or thirty-five miles 
In former ages the efforts of man to provide a refuge to the 
mariner from the fury of the raging gale were feeble and in- 
significant. Content with the harbours that nature had provided, 
it was then thought quite sufficient to line a river-bank with 
quays or to enclose a natural pond by walls. The idea of raising 
colossal breakwaters by casting whole quarries into the deep, or 
of extending artificial promontories far into the bosom of the 
ocean, is of modern date, and would have appeared chimerical 
not only to the ancients but to our fathers not a century ago. 
The first great work of this description is the famous break- 
water planned by De Cessart in 1783, and terminated in 
1853, which has converted the open roadstead of Cherbourg 
into a land-locked harbour. Rising from a depth of 40 feet 
at low spring tides, on a coast where the floods attain a height 
of 19 feet, it opposes a front of 12,700 feet to the fury of the 
storm, and carries 250 pieces of the heaviest cannon on its for- 
midable brow. 
It far surpasses in extent and boldness of construction the 
breakwater at Plymouth, nor will it be eclipsed by the moles now 
forming at Portland, Holyhead, and Alderney; but although 
it is a more impressive spectacle to see man struggling with the 
ocean and producing calmness and shelter in the midst of the 
raging storm, than to contemplate his operations where he has 
no such adversaries to subdue, still such buildings as those just 
described are neither the largest nor the most expensive works 
