THE OPEN SEA 
119 
the ‘‘mountain high” that we hear about so 
often from the returned tourist. It is not even 
hill high. It has been asserted that off the 
Cape of Good Hope waves one hundred and 
eight feet in height have been seen, but one 
may venture to doubt the assertion. The Cape 
of Good Hope region has always furnished the 
marvellous in sea-tales, but this one is some- 
thing too wonderful for belief. 
The breadth through or thickness of a wave 
is usually determined by its height considered 
in relation to its class or kind. On the open 
sea, where the friction of the sea-bottom is 
eliminated, the longer waves are often several 
hundred feet through from hollow to hollow. 
The long heaving swell of the tropical seas 
which moves under the ship, lifts it, and then 
passes on across the distance, its glassy sur- 
face unbroken by any dash of wave or spray, 
is probably the thickest of all ocean waves. 
The estimate has been made that it is some- 
times from five to six hundred feet in its 
largest dimension. But this long swell be- 
longs only to the region of the trade winds, 
where the push of the wind against the wave 
is regular and continuous. In localities of 
cross-winds and local storm-centres such waves 
Waves 
‘tanountain 
high.” 
Thickness of 
waves, 
