"Proceedings for the recovery, under this Act, of compensation
for an injury shall not be maintainable unless notice of the
injury has been given to the employer as soon as practicable
after the happening thereof, and before the worker has
voluntarily left the employment in which he was at the time of
the injury, and unless the claim for compensation with respect
to such injury has been made within six months from the
happening of the injury . . .
Provided always that -
(a) the want of or any defect or inaccuracy in such notice
shall not be a bar to the maintenance of such
proceedings, if it is found in the proceedings for settling
the claim that the employer is not or would not if a
notice or an amended notice was then given, and the
hearing postponed be prejudiced in his defence by the
want, defect, or inaccuracy or that such want, defect,
or inaccuracy was occasioned by mistake, absence
from the State, or other reasonable cause; and
(b) the failure to make a claim within the period above
specified shall not be a bar to the maintenance of such
proceedings, if it is found that the failure was occasioned
by mistake, absence from the State, or other reasonable
cause."