Special schools for physically or mentally deficient children.

If there is in existence a special school within the prescribed distance from the residence of a child who is suffering from a physical or mental defect, the attendance authority may, if it is satisfied that the child is not receiving any instruction in some other manner considered by it to be satisfactory, by order, require the child to attend the special school; and it shall be the duty of such child to attend the special school unless there be a reasonable excuse for the non-attendance of the child within the meaning of clause (e) of Section 16.