Engines Erected on Cornish Mines

MS 3147/5/Engines Erected on Cornish Mines

Engines Erected on Cornish Mines

1777 - 1821

Span date of drawings: 1777-1821
Date of engines ordered: 1776-1800

Portfolios 1281 to 1326 contain drawings of engines sold to Cornish mines. The majority of the engines depicted here are water pumping engines. Atmospheric engines had mainly been used for pumping water and many had been erected in Cornwall, so Cornwall became Boulton & Watt's first major market, and these portfolios contain some of the firm's oldest drawings; many of the drawings from the 1770s in these portfolios are by Watt himself. These engines worked the pumps directly; the pump apparatus was linked to the engine beam by a connecting rod. This method continued to be employed throughout the firm's life, and the majority of the drawings in this series depict engines working pumps directly from the beam. The steam engine underwent considerable development during Boulton & Watt's involvement in Cornwall, so while the earlier engines are single-acting, with chains connecting the piston rod to the beam, from the 1780s there are drawings of double-acting engines with parallel motions.

Boulton & Watt also sold a few rotative engines in Cornwall; some of these were used for pumping and others for winding ore ("whim" engines). The engine planned for Dolcoath Mine but sold to Wheal Maid [Portfolio 5/1326] is one of the earliest Boulton & Watt winding engines.

The exact number and location of the Cornish engines is confused, due to the early date of the engines, the lack of drawings of some of them, the similarity in the names of some of the mines, the fact that several individual mines would come together to form a single concern, and the fact that engines were frequently sold on from mine to mine, often with new books of drawings being opened for new customers. Some engines worked at as many as five different mines. The List of Engines made at Soho gives a "Diary of Engines in Cornwall", listing the movements of each engine, as well as a list of the engines still at work in May 1798 and a list of the various pirate engines; the brief histories of the engines given in this list are based largely on that volume and on Dickinson & Jenkins, James Watt and the Steam Engine, and the researcher is referred to those books and the Catalogue of Old Engines for further information. Further information about almost every Cornish engine is contained in the bundles of correspondence from Thomas Wilson, Boulton & Watt's Cornish agent, and in the various bundles of other Cornish letters and papers.

Henry Hazleton appears to have put the portfolios in no particular order during his work on the drawings in the 1890s. He listed the engines in Section M of the Catalogue of Old Engines, where he listed them in roughly chronological order, but with engines for the same mine listed together. He also included several engines for which no drawings exist.