Sect. 1. Every twelfth year, after this constitution shall have taken effect, at the general election held for Governor there shall be a poll opened, in which the qualified Electors of the State shall express, by vote, whether they are in favour of calling a convention, or not, and if there should be a majority of all the votes given at such election, in favour of a convention, the Governor shall inform the next General Assembly thereof, whose duty it shall be to provide, by law, for the election of the members to the convention, the number thereof, and the time and place of their meeting; which law shall not be passed unless agreed to by a majority of all the members elected to both branches of the General assembly, and which convention, when met, shall have it in their power to revise, amend, or change the constitution. But, as the holding any part of the human Creation in slavery, or involuntary servitude, can only originate in usurpation and tyranny, no alteration of this constitution shall ever take place so as to introduce slavery or involuntary servitude in this State, otherwise than for the punishment of crimes, whereof the party shall have been duly convicted.