Ord-Hume discusses Fortunio Liceti's "De Lunae Subobscura Luce prope coniunctiones", which turns out (I think) to be Chapter 50 (L) of his 1640 book "Litheosphorus": there's an online scan at the Wolfenbütteler Digitale Bibliothek here, though (once again) it turns out to be only some six pages long.
Though Ord-Hume mentions various bits from Della Porta, his main source seems to be the section in Bishop John Wilkins' 1648 "Mathematicall Magick, or The wonders that may be performed by Mechanical geometry" entitled "Subterraneous lamps, diverse historicall relations concerning thsir duration for many hundred years together".
I'd heard of the book before: it merits a mention on p.309 of William Eamon's enjoyable "Science and the Secrets of Nature" (1994), who notes both that it used the word "Magick" in an ironic sense, because "vulgar opinion... doth commonly attribute all such [machines and devices] unto the power of Magick", and that Isaac Newton was an "avid reader" of it [as was Christopher Wren]. Also on my bookshelf is "The Rosicrucian Enlightenment Revisited" (1999), where Paul Bembridge (in his article "Rosicrucian Resurgence at the court of Cromwell") briefly namechecks Wilkins' mention of the eternal lamp allegedly in the tomb of Christian Rosenkreutz. (It's in Yates too, of course).
[Incidentally, because Curse readers will remember my discussion of early modern wind-powered cars, I should say that Wilkins also talks about Simon Stevin's wind-wagon, and even includes a rather faked-up line drawing of it (you can see a copy of it here).]
Yes, I'd love to buy a proper copy of Wilkins' book, but... a first edition apparently went at auction earlier this year for £1000: oh, and there's a copy at B & L Rootenberg up for $3500. OK, the dollar's weak, but it's not that weak, right?
Thankfully, Kessinger Publishing sell (for rather less cash) a print-on-demand reproduction which you can buy through Amazon etc: but note that (rather unhelpfully) they've modernised the spelling of the title to "Mathematical Magic". Anyhow, I've ordered a copy, and will post a blog entry about it when it arrives...