When such appointments are made by the Governor, such person shall receive as compensation for his services while so acting as associate justice of the Supreme Court for the time actually engaged in performing such services the same salary allowance and expenses and stenographic hire as an associate justice of the Supreme Court would receive for the same period. Such salary and expense allowance shall be figured in the ratio that the number of days such acting associate justice is actually engaged in sitting with the court bears to the number of days that the court is actually in session during the year, except that in the event such acting associate justice shall sit and hear only one cause he shall receive only fifty per cent of the salary and allowances herein fixed.