I heard a Fly buzz – when I died –
The Stillness in the Room
Was like the Stillness in the Air –
Between the Heaves of Storm –
The Eyes around – had wrung them dry –
And Breaths were gathering firm
For that last Onset – when the King
Be witnessed – in the Room –
I willed my Keepsakes – Signed away
What portions of me be
Assignable – and then it was
The first two lines illuminate for the modern reader the nineteenth century American Puritan rituals surrounding death.  Family and friends weep and grieve, but then compose themselves for the moment of passing; hnece “Breaths were gathering firm”.  There would be a priest at the bedside, who would say a prayer for God to take the soul of the dying. This appears to be an almost tangible process, with God — or “King”— believed to be physically present in the room. 
 The nouns “Eyes” and “Breaths” signify weeping and uneasy breathing, an example of  synecdoche . 
 The prolifieration of dashes creates a choppy, uneven rhythm that may suggest the fear and awe of those watching the speaker’s final moments.
I heard a Fly buzz 465