Explanation For the purposes of this section, disablement means such disablement as incapacitates an employee for the work which he was capable of performing before the accident or disease resulting in such disablement." Sub ss.(2) and (3) of s.4 of the Act provide as follows: "4(2): For every completed year of service or part thereof in excess of six months, the employer shall pay gratuity to an employee at the rate of fifteen days ' wages based on the rate of wages last drawn by the employee concerned: Provided that in the case of a piece rated employee, daily wages shall be computed on the average of the total wages received by him for a period of three months immediately proceeding the termination of his employment, 674 and, for this purpose, the wages paid for any overtime work shall not be taken into account: Provided further that in the case of an employee employed in a seasonal establishment, the employer shall pay the gratuity at the rate of seven days ' wages for each season. ' "4(3): The amount of gratuity payable to an employee shall not exceed twenty months ' wages.