Indeed, the time is determined by the poetry, for "yon hard crescent" shows that the moon was up when he was writing.
"A Key to Lord Tennyson's 'In Memoriam'"
Alfred Gatty
I didn't marry yon for a home.
"The Greater Inclination"
Edith Wharton
Try a drappie o' that whuskie, laddie; that and yon cigar will mak' ye forget all about the trouble wi' the girl.
"One Maid's Mischief"
George Manville Fenn