Dr. Paul Telford Petrie (c1883-1930), chief engineer of the Manchester Steam Users Association
1891 Francis S Sleinthall 36, worsted yarn merchant, lived in Otley, with Emelina Sletinhall 35, sculptor, Paul T Sleinthall 8, Dorothea Sleinthall 6, Francis E Sleinthall 4, Paul C Sleinthall 2
1901 Lived in Ilkley, with his mother Emmaline Steinthal 45, Francis Eric Steinthal 14, Paul Cuthbert Steinthal 12
1903 Apprentice with Petrie and Co, Rochdale
1907 Draughtsman with G. A. Steinthal and Boydell of Bradford
1907 Estimating engineer with the Electrical Co of London (A. E. G. of Berlin); outside engineer and branch manager in the Birmingham and Leeds offices.
1908 Proposal to join Inst of Civil Engineers
1913 Part director and works manager (on own account) of small machinery manufacturer (Marriott and Stewart of Twickenham), also part time consulting engineer of Victoria St., London
1914 Name changed to Paul Telford Petrie by deed poll
1921 Proposal to join Inst of Mech Engineers
1929 Member I Mech E
1930 Obituary 
Dr. PAUL TELFORD PETRIE was reporter to the Steam-Nozzles Research Committee of the Institution and was responsible for the five Reports of the Committee published between 1920 and 1927.
His death occurred at the untimely age of 47, only a year after attaining the high position of chief engineer of the Manchester Steam Users' Association.
He received his technical education at the Yorkshire College, Leeds, where he graduated at the age of 20.
After spending two years at the works of his grandfather, Messrs. John Petrie and Company of Rochdale, he went to America and worked in the shops of the General Electric Company.
In 1907 he returned to England and was branch manager of the English General Electric Company (sic) at Birmingham and Leeds.
In 1909 he carried out a research at the Yorkshire College under the direction of Professor Goodman and obtained the degree of Master of Science. In the following year he became inspector of mechanical transport and power plants for the Crown Agents for the Colonies, and visited Belgium and Switzerland.
At the commencement of the War he had just begun to practise as an inspecting engineer in London. He was subsequently for three years head of the engineering department of Uppingham School, and in the early part of 1918 he became lecturer in mechanical engineering in the Victoria University at Manchester and in the College of Technology. With Professor Stoney be conducted a War research for the Admiralty on the production of sound under water.
In 1926 he obtained the degree of Doctor of Science. Besides his research reports, Dr. Petrie was responsible for a number of technical publications.
He became an Associate Member of the Institution in 1921 and was transferred to Membership in 1929. He was also a Member of the Institution of Civil Engineers.
"THE LATE DR. TELFORD PETRIE.
It is with great regret that we have to record the death, on May 19 last, of Dr. Paul Telford Petrie, M.Inst.C.E., M.I.Mech.E., Chief Engineer to the Manchester Steam Users Association. Born in 1883, Dr. Petrie was only 47 years of age at the time of his death, which occurred at his home, Lymm, Cheshire. He received his general education at Rugby, and on leaving this school in 1901, took the Engineering Course at the Yorkshire College, now the University of Leeds, from which he graduated in 1903 with the degree of B.Sc. (Eng.). To acquire practical experience he then spent a year in the shops of Messrs. John Petrie and Company, Rochdale, a firm which had been founded by his grandfather, and supplemented this by another year at the works of the General Electric Co, Schenectady. On his return to England he was employed in the London office of the A.E.G. of Berlin, and later on was entrusted with the management of their offices at Birmingham and Leeds.
With a view to securing the degree of M.Sc., he carried out at Leeds, in 1909, an elaborate series of experiments on the deflection of flat plates, the results of which formed the subject of a paper published in Engineering, vol. xci, page 677 (1911). He subsequently secured a position as one of the outside inspecting staff of the Crown Agents of the Colonies, but, in 1912, started work on his own account as consulting and contracting engineer, with offices in Victoria-street, S.W.l.
This venture was brought to an end by the outbreak of the war. A damaged hand made service in the Army impossible, so Petrie undertook work first as science master, and later as head of the Engineering Department at Uppingham School. This was followed by an appointment as University lecturer at the Manchester College of Technology, where, on behalf of the Lancashire Anti-Submarine Committee, Petrie made an experimental investigation into the production of sound under water. He was best known, however, in connection with the work of the Nozzles Research Committee, with which he was associated first as superintendent, and finally as reporter.
This committee was formed by the Institution of Mechanical Engineers in 1914, but the outbreak of war made it impossible to do more for several years than discuss schemes, decide on the general line of attack, make a few simple experiments, and fix on the type of apparatus to be used. Further delay was caused by the great inflation of prices which followed the Armistice. Petrie was not at this time a member of the committee, but as soon as a start on the experimental work became possible, he was appointed to the post of Superintendent and had the tedious task of overcoming the pioneering difficulties always associated with novel apparatus. It took some months’ hard work to discover the best means of conducting the experiments, and to trace to their source some of the perplexing anomalies encountered. It was during this trying period that Petrie discovered the phenomenon which he subsequently denominated the “ flapping ” of the jet. He found that a vacuum might form between the jet and the flat surface of a nozzle plate. This caused a diversion of the angle of flow, and proved exceedingly troublesome until means were, taken to ebminate it. This observation led both directly and indirectly to a marked improvement in nozzle design. Of the six reports issued by the Nozzles Committee, Petrie was responsible for the drafting of five, and on Dr. Stoney relinquishing, in 1926, the post of reporter to the committee, Petrie was appointed to succeed him. During almost the whole of this research, Petrie retained his post as University lecturer, taking the degree of Doctor of Science in 1926. In 1928, he received the appointment, on the retirement of Mr. C. E. Stromeyer, of chief engineer to the Manchester Steam Users Association.
Petrie was the author of a number of text-books, and was a contributor to the Dictionary of Applied Physics as well as to the technical Press. He was elected Associate Member of the Institution of Civil Engineers in 1908, and transferred to the class of Member in 1929."