Here the printer’s manuscript reads “after many days wandering in the wilderness”. The 1830 typesetter interpreted many days as a possessive noun phrase and the following wandering as a gerund, and thus he added an apostrophe to the end of many days. Such a reading is theoretically possible. This kind of gerundive construction does occur in the Book of Mormon text, although rarely for full noun phrases; there is only one clear example in the original text—namely, “all mankind’s becoming carnal” in Mosiah 16:3 (for discussion, see under that passage).
Here in Mosiah 9:4, it seems more natural to treat many days as the object of the preposition after and the phrase “wandering in the wilderness” as a participial clause that adds additional information, but nonrestrictively. For this interpretation, the apostrophe would be incorrect. Elsewhere the text has four examples of “after many days”; in each of these cases, many days is the object of the preposition after:
In none of these cases is there any following participial clause.
Another possibility would be to interpret many days in Mosiah 9:4 as an adverbial noun phrase, which would mean that the after-phrase here is equivalent to “after wandering many days in the wilderness”. There is one reading in the text that provides some support for an adverbial interpretation:
But this example does not follow the word order of Mosiah 9:4 (that is, it does not read “after many days being in the wilderness”).
The most natural interpretation for Mosiah 9:4 is to consider the phrase “wandering in the wilderness” as a participial clause acting nonrestrictively. Under such a reading, the apostrophe should be removed from the end of many days since this phrase would be acting as the object of the preposition after.
Summary: Remove in Mosiah 9:4 the apostrophe that the 1830 typesetter placed at the end of many days; the phrase “wandering in the wilderness” seems most naturally to be a present participial clause that provides additional information about the prepositional object many days.