| Description | These agreements between Boulton & Watt and their customers are for sun & planet engines.
The sun and planet gear was a mechanism for converting the reciprocating motion of the engine beam into rotative motion to power textile mills, grindstones, tilt hammers, rolling mills etc. Watt developed the sun and planet gear as an alternative to the crank, as this was the subject of a patent taken out by James Pickard, dated 23 Aug. 1780. Watt included the sun and planet gear in his patent of 25 Oct. 1781, and the majority of sun and planet engines were built between 1784 and 1800. Pickard’s patent expired in 1794, but Boulton & Watt continued to employ the sun and planet gear until around 1803.
The agreements are on parchment and are signed, sealed and witnessed by both parties unless otherwise noted. From the early 1790s basic lists of the metal materials of the engine were attached, and from June 1797 these lists were incorporated into the parchment.
From evidence in the List of Contents of the Watt Room (MS 3147/10/14), it is clear that in the 1890s Henry Hazleton arranged the parchment agreements to mirror the arrangement of the drawings in the "Catalogue of Old Engines". He divided the agreements by type of engine corresponding to the sections in the "Catalogue" – sun & planet, crank etc. Sun & planet engines are listed in Section A of the "Catalogue". He further sub-divided the sun & planet engine agreements, by geographical area, in order to mirror his arrangement of the entries in the "Catalogue". He referred to the agreements in the Catalogue, calling them "parchments" and transcribing details of the partners, payment etc. for each engine.
Hazleton’s arrangement was lost after the collection left Soho Foundry, and the agreements for the various different types of engine got mixed together. All the sun & planet engine agreements have been re-united, but the division into geographical areas has not been restored, as Hazleton never physically arranged the portfolios of drawings in this way, despite his arrangement on paper in the "Catalogue." The agreements have now been listed chronologically, in order to reflect the arrangement of the portfolios of drawings as closely as possible. Cross-references to the portfolios of drawings have been made where the engine can be positively identified. |