I posted this cover on another thread when I first got it, but thought I should start a fresh train of thought here.
Can any of you give me an idea what the postal rate for this stampless folded letter may have been in 1841? The rate is handwritten in the upper right corner, and I can't make it out.

The letter was sent by John Lyons, a Niagara Crown Agent who lived in Niagara-on-the-Lake to Samuel Street a prominent business man in Chippawa near Niagara Falls. The distance is about 29km between towns, assuming of course that Lyons was writing from his home.
Any thoughts?