Peake No.3 is an engine of distinctive design, this being serial number 10 (not a limited edition). The distinguishing feature of this model is that it uses sun & planet gearing instead of a crank.
The single acting oscillating cylinder is 8mm bore and 23.5mm stroke. The connection to the flywheel shaft is through a pair of gears in a sun & planet configuration. This means that the flywheel rotates at twice the rate of the piston. This arrangement was the invention of Boulton & Watt and it's main purpose was to circumvent the patent for the simple crank, already taken out by a competitor. It increases complexity and has no intrinsic advantage over a crank other than the increased speed of the flywheel. It's purpose here is mainly novelty and I believe it may be the first oscillating cylinder engine produced commercially with this gear.
The main bearing is fitted with an oil cup with an ornate cap. The flywheel is 47mm diameter and has a small convex pulley is mounted adjacently. This type of pulley is suitable for flat belting. The whole is supported by an ornate machined pillar mounted on a wooden base.
The bottom picture on the left is a scan of a "Certificate of Authenticity".