Section 7
SEC. 7. Said grantee shall file its written acceptance of this franchise with the Secretary of Commerce and Communications within one hundred and twenty days from the date when it obtained the certificate required by section one of this Act and shall commence work under the supervision and subject to the approval of the electrical engineer of the Public Service Commission, in accordance with the plan, specifications, and estimates previously approved by the Public Service Commission, within six months' time from and after the date of filing such acceptance, unless prevented by act of God or force majeure, usurped or military power, martial law, riot, or civil commotion or other inevitable cause, and shall complete the system and have the same in operation within eighteen months from the date of such acceptance, and shall thereafter maintain a first-class electric light, heat, and power service: Provided, That in consideration of the franchise hereby granted, the grantee shall pay quarterly into the municipal treasury of the municipality above named, one per cantum of the gross earnings of its electrical business during the first thirty years, and two per centum during the remaining twenty years of the life of this franchise.