It has also taken other measures against the Chinese, and
against the Polynesians or Kanakas. Finally, we can observe
in the legislation of different countries a distinct periodic
rise and fall in the stringency of the protective provisions.
The effect of all protective measures is further prejudiced
by the fact that evasion can never be entirely prevented.
Even in the case of immigration restriction, smuggling
flourishes. Thus, it is known that on the Mexican border
whole towns live by smuggling yellow labour into the neigh-
bouring States of the Union, that Canada is the headquarters
for a smuggling trade into the United States, not of goods
alone but of immigrants as well, &c. But the difficulty of
enforcement is no argument against a regulation otherwise
justifiable. Economic policy can never compute its effects
with mathematical accuracy, and so, as in this case, must
be guided by the results of experience.
