He knew in the hour he died
That his heart had never spoken
In eighty years of days.
O for the tall tower broken
Memorial is denied:
And the unchanging cairn
The pipes could set ablaze
The ‘tall tower’ is a metaphor for his father’s father, someone Baxter looked up to.  The implication is positive, despite the distance that the old man established. 
 The exclamatory ‘O’ is an inarticulate expression of grief and regret that the man’s strength and power is ‘broken’ by age and frailty.
Elegy for My Fathers Father