4. (1) Accidents happening outside Québec also give the right to the compensation provided by this act, but only in the following cases, to wit:
(a) where the employer has a place of business or an undertaking in Québec and the residence and usual place of employment of the workman are therein, provided that the employment outside Québec has not exceeded eighteen months and that it was the direct continuation of employment in Québec, in the service of the same employer;
(b) where the workman, who has his residence in Québec, is obliged by the nature of his employment in a transportation business by land to perform his work within and without Québec;
(c) where the workman, who has his residence in Québec or was hired therein, is obliged, by the nature of his work in a transportation business by water, to perform his work partly within and partly without Québec, if the vessel on board of which the workman is employed is registered in a Canadian port or if the owner or charterer of such vessel has his domicile or principal place of business in Québec.
(2) Compensation payable in respect of an accident happening elsewhere than in Québec shall, except where the employer has fully contributed to the accident fund in respect of all the wages of workmen in his employ who are engaged in the business in which the accident happens, be paid by the employer individually. The business carried on elsewhere than in Québec by an employer who has not so contributed to the accident fund shall be deemed to be included in Schedule C.
(3) When work is done partly in Québec and partly in another province, the Gouvernement may authorize the Commission to enter into one or more agreements, with any organization administering in another province an act respecting workmen’s compensation, respecting the reimbursement to such organization of the sums paid as compensation or medical aid or for rehabilitation up to the amounts which the Commission would have been required to pay under this act, and also respecting the fixing, apportionment, adjustment and payment, by employers, of equitable assessments.