Original Source: Bi-centennial of Old Kennett Meeting House, Kennett Township, Chester Co., Pa., seventh day, ninth month, twenty-fourth. Philadelphia: Walter H. Jenkins, 1910.
This is a publication based on the bi-centennial celebration. The section entitled "History of the Meeting, Etc." which gives the records of families seems to used mixed date formats, and there does not appear to be any formal explanation of how dates were handled. On the same page, one might find a date in the form "3 mo. 1781", "4,5,1754", and the most common form "6-23-1730". So one is left to guess whether month numbers have been modernized, or given in the style of the time.