The Commissioners may require security to be given to them by the landowner, by bond, deposit, or otherwise, in such form as they may think fit, for the payment to them of the expenses which they or their officers shall incur in respect of the investigation on any application, and, if they shall issue such provisional or other sanctioning order as herein-after mentioned, of the expenses which they or their officers shall incur in inspecting and ascertaining the due execution of the works; but unless the Commissioners shall issue such absolute order as herein-mentioned, such payment shall not be a charge on the land to which such application relates, but shall be a debt due by the person making such application to the Commissioners, F1. . ..