A common Windsor armchair can be converted into a merlin chair by adding a pair of bath-chair wheels with a polished wood driving rim (see A in the sketch); the axle is bolted to the cross spindles. The chair is supported at the back by a wrought-iron fork C and an 8-in. wheel; this fork passes through the back spindle (not shown). A footboard is housed into the front leg stumps and is secured by a chain as shown at B.

Self-propelling Chair for Invalid.