John Theophilus Desaguliers
John Theophilus Desaguliers FRS (12 March 1683 – 29 February 1744) was a French-born British natural philosopher (scientist), clergyman, engineer and freemason. He was elected to the Royal Society in 1714 as experimental assistant to Isaac Newton. He had studied at Oxford and later popularized Newtonian theories and their practical applications in public lectures.
See Wikipedia entry.
Desaguliers was a prolific contributor to the work of the Royal Society. See here for links to Desagulier-related archives held by the Royal Society.
He disseminated a great deal of information which would have been of value and a source of inspiration to a wide range of scientists and engineeers. He was something of an inventor, but was not averse to using the ideas of others without giving due credit. He probably effected improvements to others' inventions by applying rigorous scientific principles. Generations of historians have not been slow to point out biased and misleading claims made by Desaguliers.
Between 1717 and 1718 Desaguliers designed a number of steam pumps of the type invented and developed by Thomas Savery. He improved it by adopting water injection to condense the steam (as first used on the Newcomen Engine and installing a safety valve (invented by Denis Papin. 
Sources of Information
- 'Thomas Newcomen' by L T C Rolt, David & Charles, 1963
- 'A Descriptive History of the Steam Engine' by Robert Stuart, first published 1824. Published by Nonsuch in 2007. See pp.68-71
- 'A Treatise on the Steam Engine' by John Farey, Vol 1, 1827. David & Charles reprint, pp.110-6