Math-play via verse (with George Darley)

A recent email from Colm Mulcahy -- who seeks out all things Irish -- alerted me to Dublin poet and math-text author, George Darley (1795-1846), and an online archived collection of his poems.    Colm's email had opened the collection to pages 70-71 and there I found -- and had fun reading --  this poem that plays with math.

     A Poetical Problem.      by George Darley

     Once on a time, at evening hour,
     A sweet, and dewy-bosom'd Flower
            Was cradling up to rest ;
     A Pilgrim, wandering near her bed,
     Raised, with his staff, her drooping head,
            And thus the Flower addrest : 

     "From matin-rise to moonlight hour,
     Tell me, my pearly-crested Flower,
            How many a lucid gem
     Hath left the high, cavernal air,
     To form upon thy queenly hair
            A rainbow diadem?"