Short vowels in lucubrando

Question

I came across a poem from 1621 written in Sapphic stanza. It contains this line:

pervigil Christi, lucubrando sudans

To scan that, the third word must be lŭcŭbrandŏ. L&S tells me that the first U should always be long and the second one can be either long or short. The O of the gerund ablative ending should be long.

Classic vowel length is otherwise observed very well throughout the nine stanzas of the poem. This line is a striking exception.

I know that if the second U is short, then the second syllable is short (light), since the combination 'br' does not behave like most consonant clusters. But that is irrelevant.

I want to understand what is going on. Therefore I would like to see an answer to at least some of these questions:

• Would such shortened vowels be bad style in classical poetry? I would say yes, but I could use a second opinion.
• Is such shortening a general post-classical phenomenon? Or should I see this line just as poetic liberty to accommodate a word the author wanted to use?
• Is the final O in the gerund ablative still known to be long in the 17th century? As far as I know, everyday Latin speech at that time did not follow classical vowel lengths, but the rest of this poem demonstrates that people were able to emulate them when needed. In two other places in the poem where length matters, the second declension ablative or dative ending is long. I therefore wonder if the short O is something specific to gerunds.
• Why are the vowels short?

Answer 1

I don't know any reason why the first vowel of "lucubrando" would be short; I'd guess it might be an error.

However, I was able to find some references that describe final o as often being treated as "common" (able to be long or short) for various words in various eras of poetry, and in particular in gerund.

In Adam's Latin Grammar, by Alexander Adam, from 1827, we find the following passage:

O final is common; as, Virgo, Amo, quando. [...] The gerund in DO in Virgil is long; in other poets it is short. (180)

So this at least mentions the phenomenon; I don't know how accurate this description is for Classical usage, however.

Another description from around 1898, in A Latin Grammar for Schools and Colleges by George Martin Lane, makes it seem less common:

Final o is short [in various listed words] and in many other words in late poetry : as īlico, immo, ergo, quando, octo, &c. ; very rarely in the ablative of the gerund. (447)

A book by Neil Wright about the Medieval Latin poem Gesta Regum Britannie says that in it "the ablative singular of the gerund is usually short"; obviously this is from not the classical period (it comes from the mid-1200s) but it may be a useful concrete example of another work with this feature.