For this chair I used the measured drawings in Antique Country Furniture of North America and Details of its Construction by John G. Shea, 1975.
"Shaker furniture is a distinctive style of furniture developed by the United Society of Believers in Christ's Second Appearing, commonly known as the Shakers, a religious sect that had guiding principles of simplicity, utility and honesty. Their beliefs were reflected in well made furniture of minimalist designs." Wikipedia - Shaker furniture.
"Of the many types of furniture they produced, the Shakers were most prolific in their manufacture of chairs and rockers. Chair makers of the New Lebanon community started building their own distinctive designs, some for sale to outside markets, during the 1790s - and their business continued well into the twentieth century." John G. Shea, 1975, p60.
Note that one of the views shows the chair apparently leaning back. This is not a mistake, but an early attempt to make the chair more comfortable. It makes for a more complicated construction as all of the mortise holes for the side rails need to be drilled 3 degrees off 90. Later chairs had the back post bent in a shallow v so that both the back and leg angled backwards making for a more stable chair combined with comfort.
Further information about Shaker chairs, connecting design variations to the different communities, can be found in :
The Shaker Chair by Charles R. Muller and Timothy D. Rieman, 1984