Which preposition to use with vaticinating

from Occurrences 2%

" Words that sounded beautifully, because they were true as regarded Rachel, whatever they might be as respected his secret intention; yet as the children vaticinate from the examination of each other's tongues, if the uncle had examined the organ, he might have discovered some of those blue lines which produce an exclamation from the young augurs.

in Occurrences 2%

Console yourself by vaticinating in the bower of your bed-chamber, as you count the feet upon your fingers, your own immortality.

Which preposition to use with  vaticinating