1777 Aspinwall American Revolutionary War Cipher

This came from a group of items related to a prominent shipper from the New York/Pennsylvania area. The documents were mainly from the late 1700s and early 1800s, but there were a few items earlier including this item and a Virginia note from 1776. From everything we know these items were passed down through the family over the years, the two men that were heavily represented in the collection were Legrand Cannon and Wakeman Burritt who were both born in the 1700s and seemed to have had a fairly large shipping company by the early 1800s.

Wikipedia - Intelligence in the American Revolutionary War
Wikipedia - Intelligence Operations in the American Revolutionary War
CIA - Intelligence in the War of Independence
Amazon: Travels in Britain 1794-95, the Diary of John Aspinwall

The outer side of the Aspinwall cipher. (Click on image for an enlargement.)
It reads:
Cypher for Aspinwall (in brown ink)
July "2" (in pencil?)
1777 (in blue ink?)

Beneath these lines, three others have been erased:
Infrared imagery ("reflectograms") courtesy of William Brown and Noelle Ocon, North Carolina Museum of Art.
Camera: FLIR, model xxxx. Filter 1 um.

Reflected daylight.
Reflected infrared.

Below, transmitted IR "reflectogram" of the paper structure.