The Election Commissioners shall certify to the Mayor the result of the vote, and if a majority of the qualified electors voting on the question at such election vote in favor of the specified tax, then it shall thereafter be continually levied and collected as other general taxes of such city are levied and collected. The result of the election shall be proclaimed by the Mayor. The result so proclaimed shall be conclusive unless attacked in the courts within thirty days. The proceeds of any tax voted for the maintenance of a city public library shall be segregated by the city officials and used only for that purpose.