55 
DEEP-SEA LAMPS. 
The possibility of exhibiting the powers of electrical 
fishes in the tanks at the Zoo, suggests the question 
whether, in the progress of marine aquariums, we shall 
ever see the luminous creatures of the deep seas 
exhibited alive before air-breathing mortals in this 
upper world. Virgil’s Sybil set the depth of Tartarus 
at twice the skyward gaze to the summit of Olympus. 
But the profundity of the ocean abyss is such that in 
the deep Atlantic Olympus might be imposed upon 
itself, and Ossa piled above, without rising to break 
the surface. The imagination almost refuses to grasp 
the physical conditions in an abyss so profound as the 
ocean bed off the coast of Porto Rico, wrapped, by a 
weight of waters five miles deep, in perpetual darkness 
and everlasting cold, and under a pressure of which 
figures can convey no practical conception. Even at 
the average depth of 2,500 fathoms sunlight can never 
penetrate. The temperature is only a few degrees 
above freezing-point, the water is without movement, 
there is no plant-life, and the pressure is two and a 
half tons on the square inch, or about twenty-five 
