How did the fugitive act in the 1850s benefit the north?

The Act was one of the most controversial elements of the 1850 compromise and heightened Northern fears of a "slave power conspiracy". It required that all escaped slaves, upon capture, be returned to their masters and that officials and citizens of free states had to cooperate.

the effect of the ming leaders banning ships with more than two masts was that there was no further construction of ships masts, because there was a surplus. ming emperors disallowed foreign exploration