old tall case clock

To whom it may concern:
This story is about a very old tall case, weight driven clock, and its unusual features.
It stands 90 inches high by 181/2 inches wide by 11 1/2 inches deep.
I bought this clock at an auction about a month ago for $100.
What makes this clock unique is that it has brass gears with a wooden frame, the gears ride on small metal inserts in wooden frame.
It has two hollow tubes that have sand and small rocks in them attached to two chains, and when pulled up, the clock will run for about a day.
The actual wood face is shaped so that the round handpainted clock dial is raised from the wood face.
Clock appears to be put to geather with hand made nails and pegs.
Unfortuntly the clock class must have been broken and replaced at one time because glass is newer than rest of clock.
The finish is painted and the clock face must have been touched up.
The wood clock face locks to wood clock frame with wire type hooks and by doing so the clock and face are held securely in place.
The clock appears to be completely hand made.
Another interesting fact is that on the back of the faceplate is handwriting in pencil:Wm. Johnson, January 6th 1818 and below it in a diffrent handwriting cleaned Feb 22, 1849 W. L. Eiden.
Also on the inside of the back wood cover is handwriting in pencil: Repaired by Wm. Johnson, January 6th 1818, March 18, 1845.
Their is a bell on top, which goes off for each hour on the hour.
My guess is that this clock is really old, as a matter of fact the only reason the pencil handwriting is visible is because the writing faced the inside of clock and was not exposed to the light, all other sections exposed to the light are very dark.
My question is, how old is this clock? and is it just a nice old clock or does it have real value.
Thank you, John Slawenski