1889. | NEW YORK ACADEMY OF SCIENCES. 169 
there would have to go through these calms. The mariner who 
attempts to cross this region in asailing-vessel, is, as a rule, sub- 
jected to heart-sickening detention. His vessel is apt to lie for 
day after day and week after week,—and sometimes for month 
after month,—listlessly on the glassy waters. If the sails fill 
with wind, and his heart begins to beat with joy, he is very apt 
to find that only a momentary breeze has swept by, or that a 
squall ushering in a tropical shower threatens his vessel with de- 
struction. When thesun shines, it does so with a heat so scorch- 
ing as toinjure in various ways the vessel and to make the sailors 
prematurely old. As the sailor finds that day after day he makes 
scarcely any progress, he is apt to feel that he would far rather 
face the storms, and sail 10,000 miles to round Cape Horr, than 
have his life wasted in a region of calms. But few sailing-vessels 
would probably attempt a second time to go from New York to 
the Pacific Ocean by way of Panama. Skilful navigators might 
indeed get through the region of calms in but one or two weeks’ 
longer time than it would usually take for them to go by way of 
Nicaragua,—that is, if they knew just how to keep on the borders 
of the region of calms, or just what course at all times to take; 
—but on every round trip a sailing-vessel, under the most favor- 
able circumstances that it could expect, would lose much time. 
Tehuantepec isseveral hundred miles further north of Nicaragua 
than is Nicaraguanorth of Panama. Vessels crossing the isthmus 
by way of Tehuantepec would often have a breeze when vessels 
going by way of Nicaragua would meet with no friendly wind. 
If two sailing-vessels should start from New York or from New 
Orleans, for almost any port of Asia or Australia, one of them 
going by way of Tehuantepec and the other by way of Panama, 
as a rule the one going by way of Tehuantepec would be thou- 
sands of miles on its journey,—perhaps at the Sandwich Islands, 
if its course lay in their direction,—while the other would be 
lingering in the region of calms. 
While a wooden sailing-vessel is lying becalmed off the coast 
of Panamait is attacked beneath its water-line by what are called 
ship-worms. The species of ship-worm known as the Zeredo 
navalis is now to be found probably in every sea. These crea- 
tures did such injury to the piles which were used on the great 
dikes that protect Holland from the ocean,—dikes which have cost 
not less than $1,500,000,—that the Dutch Government has at 
times appealed to science to deliver them from their attacks. 
These ship-worms, when very young, attack wooden vessels that 
are not covered with copper sheathing, or in some such way pro- 
tected from them. ‘The holes by which they enter the sides of 
a ship are no larger than pins’ heads, but when they have once 
entered the wood they grow rapidly. They line their bores with 
