|329 By what it fed on, and yet within a month,||1.2.145|
Ed. summary: Trench (1913) explains the import of these lines: it isn’t that Hamlet is shortening the time irrationally as some commentators think; rather, the funeral took place a month after the king’s death.
Seymour ≈ pope’s practice
329 and] [Seymour (1805, 2:147), who is using a Johnson-Steevens edition, says, “And should be omitted here, as useless to the sense, and burthensome to the metre.”
329 MacDonald (ed. 1885, p. 62): “within a month of his father‘s death, his mother’s marriage with his uncle—a relation universally regarded as incestuous—plunges him in the deepest misery.”
329-32 within . . . bodie] Verity (ed. 1904, pp. xxxvi-xxxvii): <p. xxxvi> “Essex’s mother Lettice married the Earl of Leicester a few days after the death of her </p. xxxvi><p. xxxvii> husband (commonly thought to have been poisoned by Leicester). [. . . ] ” </p. xxxvii>
Ed. note: DNB: The Earl of Essex, Walter Devereux, who had married Lettice Knollys, both age 20, in 1561, died of terrible dysentery at age 35, 22 Sept. 1576, in Ireland. There were suspicions of poisoning, so much so that he was disinterred and the body examined, but nothing was found. Rumors persisted and a ballad was written, ascribing the murder to an adulterous affair. Lettice did marry Essex’s enemy Leicester two years later, 21 Sept. 1578. The DNB lays out the many opportunities Leicester and Lettice had to be together while Devereux was in Ireland, vainly trying to put down the Irish and Scots. DNB does not think she had anything to do with Essex’s death.
329 within a month] Trench (1913, p. 54): “Here now is Hamlet alone. Here now we can follow the workings of his mind. And we learn—none of the people ever suspected this—that he is mourning, not for his father, but for his mother; that what makes his ’heart break’  and life no longer seem worth living is not a sense of personal loss, but a sense of human depravity as exemplified in the re-marriage of her whose ’frailty’  seems to implicate all womanhood. Within ’two months’  of her first husband’s death, ’within a month’  of the state funeral, she has married again, and this’most wicked’  unfaithfulness to him whose memory Hamlet venerates renders ’most unrighteous’  all the tears she shed upon his death.”
trav ≈ Trench without attribution
329 within a month
(ed. 1929): “of the funeral  and so less than two months after the death. The remarriage it is that has made the murdered king revisit the earth.”
329 Greenblatt (2001, p.146) says that in the ghost literature it is typically dead husbands who must look on at their wives’ unfaithfulness.