The state treasurer is hereby authorized with the approval of the governor and council to borrow upon the credit of the state a sum not exceeding $3,000,000 for the purpose of carrying into effect the provisions of this subdivision and for that purpose may issue bonds in the name and on behalf of the state of New Hampshire at a rate of interest to be determined by the governor and council. The maturity dates of such bonds shall be determined by the governor and council but in no case shall they be later than 30 years from the date of issue and may be redeemable before maturity at the option of the governor and council at such price or prices and under such terms and conditions as may be fixed by the governor and council prior to the issuance of the bonds. Such bonds shall contain an express guarantee which shall be deemed a contract on the part of the state that tolls will be collected in accordance with the provisions of this subdivision and N.H. Rev. Stat. Chapter 237 until the date of maturity of said bonds or until sufficient money shall have accumulated to pay said bonds and the interest thereon at or prior to the dates of maturity. The bonds shall be in such form and such denominations as the governor and council shall determine, may be registerable as to both principal and interest, shall be countersigned by the governor, and shall be deemed a pledge of the full faith and credit of the state. The governor may authorize his countersignature on said bonds to be by facsimile signature. The secretary of state shall keep an account of all such bonds showing the number and amount of each, the time and date of countersigning, the date of delivery to the treasurer and the date of maturity. The state treasurer shall keep an account of each bond showing the number thereof, the name of the person to whom sold, the amount received from the same, the date of the sale and the date of maturity.