By his will, executed in 1936, a testator appointed his sister his sole executrix and provided that if she should be alive at the date of his death all his estate should go to her. In the event of her predeceasing him the testator left his property to certain charities. In 1939 he executed a first codicil to his will whereby he gave two sums of money to named charities and in all other respects confirmed and republished his will. Twelve days later he executed a second codicil, which was identical with the first codicil, except that before the words of gift to the charities were inserted the words, "In the event of the death before me of my said sister [Y] or in the event of the deaths of me the said [Testator] and of the said [Y] in circumstances rendering it uncertain which of us survived the other . . .". The codicil then repeated the gifts and concluded in the same manner as the first codicil, i.e., "In all other respects I confirm and republish my said will".