troduction of its benefits, and at the same time
prevents the burden of lasting monopoly. The dangers are chiefly in the
administration of patent laws, from the careless issue of undeserved
patents, or in a combination under a series of patents to maintain a
constant monopoly. It is a safe rule to issue patents only for particular
applications of scientific principles and not for the discovery of the
principle, which can be protected in publication by copyright. Departures
from this rule cut off the possibility of more perfect contrivances and
fair competition in devices and methods. There can be no question of the
general advantage of protecting a genuine inventor from the trespass of
others to secure him a fair compensation. No other plan for a fair
exchange of such services has even been suggested. The unsettled question
is the proper limit of time for a patent to run.

The advantages and disadvantages of copyright are essentially the same in
character, though the dangers are less. Since the large part of the reward
of an author or an artist is in the repute he may secure, there is little
danger of fostering an unfair spirit of monopoly. The franchise is subject
to the same principles, but its dangers in practice are very great. So
long as the advantages to the corporation securing the franchise may be
enormous, if it is sufficiently extended, there is great temptation to
bribery, both in the original issue and in the maintenance of inspection
and municipal control. Nothing has so interfered with good government of
cities as the manipulation of franchises. These abuses underlie the
popular call for municipal ownership of water works, lighting plants and
street railways.

_Protective duties._--A still more widely extended method of stimulating
industry by special incentives is seen in what is called a protective
tariff. This is a system of duties upon articles produced in foreign
countries so levied as to check the natural competition by increasing
their cost to consumers. The increased cost of such articles, if not too
great to destroy the demand, increases the incentive to manufacture
similar articles within the country.

The schedule of tariffs becomes then a very important element in all
productive industry, and requires the nicest adjustment to the needs and
abilities of the nation. If associated, as is usually the case, with the
raising of government revenues, the adjustment becomes more difficult, and
require