That book is a white-gloves effort. It's been forty years since I was in those archives. Translations might be available for different subject matter or as straight copy, but the chapter I read was full of notes, and it had interesting dialogue of a 'teluric' fluid once used to light up the stones in ceremonies. You might need to apply charm to your nearest Mage of Rosicrucian Golden Dawn mysteries to find out more. All I have here are very short notes. At the time I believe I was following research on the myth/legend of, singing the stones weightless, to move monoliths into place, considering Stones of Stonehenge may very well have travelled from Eire. The mention of 'teluric' fluid is about the ceremonies of quarters of the year.
Best of luck. Keep on keeping on😇
(*co'elera lingus ¿ - some of my handwriting might be a DR's 😆)