The "steam-jet" or "blastpipe", which served to increase the draw of air through pipes, and which was applied to improve mine and sewerage ventilation, to increase the efficiency of steam-powered stationary engines and blast furnaces, and road or rail vehicles. After the Rainhill trials of 1829, there was considerable controversy as to the genesis of this invention since it became associated in the mind of the public with George Stephenson—probably through the agency of Samuel Smiles' biography of that man. In her 1875 letter to "The Times", his daughter traces the path of the idea: Gurney communicated it to Timothy Hackworth, who employed it in his "Royal George" locomotive, from which Stephenson allegedly took his inspiration for its inclusion in the "Rocket". More recent letters acquired by the National Railway Museum suggest that, in fact, Hackworth may have discovered the idea first and/or independently; and Herbert—clearly not a fan of Gurney—seeks to debunk claims for Gurney's invention by comparing the output of Gurney's carriages with those of Trevithick. Other problems faced by Gurney's claim to have invented this is the clear use of it by Trevithick as confirmed by contemporary notes and also the patent applied for it by another party in the early 19th century.