The trustees of every savings bank, by a committee of not less than three of their number, shall at least annually fully examine the records and affairs of such savings bank for the purpose of determining its financial condition. The trustees may employ such assistants as they deem necessary in making the examination. A report of each such examination shall be presented to the board of trustees at a regular meeting within thirty days after the completion of the same, and shall be filed in the records of the savings bank.