At the election provided for by section 511.01 of the Revised Code, if a majority of all the ballots cast are in the affirmative, the board of township trustees shall levy the necessary tax, which, in any year, shall not exceed four mills on the dollar valuation. Such tax shall not be levied for more than seven years. In anticipation of the collection of taxes, the board may borrow money and issue bonds for the whole or any part of such work, which bonds shall not bear interest to exceed the rate provided in section 9.95 of the Revised Code payable annually.