Second, the Court pointed out that the two cases are distinguishable because they were decided at different points in time. The Subsidence Act showed that "'may so change in time ... as to clothe with such a [public interest what at other times ... would be a matter of purely private concern.'" Therefore, during the 44 years between the "Pennsylvania Coal Co. v. Mahon" decision and the enactment of the Subsidence Act there was a change in the public's attitude toward regulations affecting private land.