When the Commissioners are satisfied that the improvements sanctioned by them, or some part thereof, have been properly executed, either according to the specifications and plans or drawings approved of by them, or with such deviations therefrom as in their judgment will not diminish the permanent benefit accruing from such improvements to the lands wherein they have been made, they shall execute a charge under their hands and seal upon the inheritance or fee of the lands comprised in the provisional or other sanctioning order, or some sufficient part thereof, for the sum by the same order expressed to be chargeable in respect of such improvements, if all the said improvements have been completed, or for a proportional part of such sum, if a part only of the said improvements has been executed, together, in either case, with the interest by the same order expressed, and with the amount (if any) which shall have been paid in respect of the purchase of adjoining lands, or of any easement, authority, or right in, through, over, or affecting adjoining lands, with interest thereon at the like rate.