107.—Every indenture of apprenticeship to the sea service made in the United Kingdom by a board of guardians, or persons having the authority of a board of guardians, shall be executed by the boy and the person to whom he is bound in the presence of and shall be attested by two justices of the peace, and those justices shall ascertain that the boy has consented to be bound and has attained the age of twelve years and is of sufficient health and strength, and that the person to whom the boy is bound is a proper person for the purpose.