p. 1

Shippingsport Oct 21. 1827.

Dear Brother

In my last letter I promised you a description
of the Steam Engine; but I do not profess to be acquainted
with all of it's parts, or capable of giving a good discription of
it. I supposed you would read with great pleasure a discription
of this "masterpiece of human skill" writen by your brother who
is in the midst of fifty of them, consisting of all the improvements
from the oldest & most complex, to the newist and most simple; from
the power of about 60 horses Down to that of one and a half. And more particularly
as you have not had a good oportunity of examining one. However
if this should not be the case you can pass it over without read.

[drawing of steam engine parts labeled with letters]

The steqm engine consists of a hollow cylinder a,b,c,d, in which is the moveable heads. attached to the piston rods. The other end of this piston rod or is attached to the shackle bar or pitman which turns this chank. The cylander must be as long
as the stroke and larger or smaller according to the power required. A tube called the side pipe runs from each end of this cylinder to a box called the steam chest

[drawing of steam chest, parts labeled with letters)

another opening in the bottom of this chest leads to the escape pipe, these openings are at e,m,& n. e & m open to the cylinder through the pipe and n opens to the escape pipe. This chest and side pipe is represented in fig 1 by blm & ll. In the chest is a valve in the form of a square basin with it's bottom upwards. This valve d is large enough to cover two holes at once and of coarse it is always over the middle hole n and one of the others; one of the holes being always open.

In figure 1. you will see the valve with the rod attached which is attached at n to an
iron lever whos fulcrum is at o. A wheel is attached to the center of the rotary motion; one half of this wheel has a radius longer than the other half; this difference must be equal to the distance the valve is to move. this wheel is placed
in an iron square frame. a rod is attached to this frame and to the lower end of the lever at p. Now if this turns it is ?