William John Macquorn Rankine forged a distinguished career as a Scottish mathematician and civil engineer. He was a founding figure in the science of thermodynamics, with a particular focus on its First Law. However, Rankine’s contribution to science did not end there. He developed numerous other concepts that have since become part of our most valuable scientific heritage, and his publications remained in high demand for many years after his death. Read more about at edinburgh1.one.
This article will allow you to become more familiar with the life and work of one of Edinburgh’s most talented scientists. His journey is filled with a host of truly remarkable facts and events.
Early Years
Rankine was born on 5 July 1820 in Edinburgh. His father was a civil engineer with a background as a military lieutenant, while his mother came from a family of prominent bankers and lawyers.
His father’s professional duties required frequent travel around the country, and the family moved with him. After being educated at home, William began his formal schooling first in Ayr and later in Glasgow. In 1830, the Rankine family returned to their native Edinburgh.
Developing His Path
After returning to Edinburgh, William’s career began to take an interesting course. In 1834, he entered the Scottish Naval and Military Academy. Two years later, in 1836, he became a student at the University of Edinburgh. During his studies, the young man was particularly drawn to natural history and natural philosophy.
An Important Stage
It is important to note that William did not waste his time during university holidays. He gained valuable experience assisting his father, who was appointed treasurer and engineer of the Edinburgh and Dalkeith Railway.
In 1838, Rankine left the University of Edinburgh without receiving a degree. Instead, he began an apprenticeship under Sir John Benjamin Macneill, who was then an inspector for the Irish Railway Commission.
During his apprenticeship, Rankine developed a unique technique for laying out railway curves using a theodolite. This method, which became known as Rankine’s method, significantly improved both accuracy and productivity. The technique was widely adopted by other engineers, a fact that led to a dispute over priority in the 1860s.
Scientific Work
In 1842, William first attempted to create a mathematical formula for the phenomena of heat. However, he was unable to obtain the experimental data he needed, and the effort was unsuccessful.
The scientist also decided to return to the field that had fascinated him in his youth: the mechanics of the heat engine. By 1849, he had discovered the relationship between temperature and saturated steam. A year later, in 1850, William reached a new level by establishing the connection between pressure, gas density, and temperature. It was Rankine who proved a fact that became a sensation at the time: that the specific heat of saturated steam is negative.
Further Achievements
Following this success, in 1851, William began calculating the efficiency of heat engines. He concluded that the maximum efficiency of any heat engine is a function of only the two temperatures between which it operates.
It is fair to mention that a similar principle had already been put forward by Rudolf Clausius and William Thomson (Lord Kelvin). However, Rankine maintained that his result was based solely on his own hypothesis of molecular vortices, rather than on Carnot’s theory or any other assumption.
This work by Rankine later came to be regarded as the first step towards developing a more complete theory of heat.
Energy and Energetics
William’s further successes began in 1853 when he proposed the term “potential energy”. He then adapted the results of his molecular theories, using them to create a macroscopic explanation of energy and its transformation.
In doing so, William distinguished between actual energy (which is lost during dynamic processes) and potential energy (which replaces it). The scientist hypothesised that the sum of these two energies remains constant.
New Milestones
In 1855, Rankine again surprised the scientific community by formulating the science of energetics, which explained dynamics based on energy and its transformation.
Then, in 1859, the scientific community first heard of the Rankine scale. The scientist had developed an absolute, or thermodynamic, temperature scale where the size of a degree is equal to a degree Fahrenheit.
Later, Rankine expanded on Kelvin’s theory of the heat death of the universe. In 1862, he and Lord Kelvin jointly formulated the heat death paradox, which they used to challenge the possibility of an infinitely old universe.
Pioneering Work on Metal Fatigue
Rankine was the first among engineers to realise that fatigue failures in railway axles were caused by brittle fractures. He began investigating a huge number of broken axles in the early 1840s.
He delved even deeper into this issue after the tragic Versailles train crash in 1842, where a locomotive axle suddenly failed, leading to the deaths of over fifty passengers.
Rankine proved that the axles failed due to the growth of a small crack originating from a sharp corner or keyway. He presented his findings in a paper to the Institution of Civil Engineers. Unfortunately, his work was ignored by his colleagues, who firmly believed in the myth of metal “re-crystallising” under stress.
The re-crystallisation theory was entirely baseless and incorrect. Worse, it discouraged proper research into the problem for years, until the work of William Fairbairn finally proved the weakening effect of repeated bending on large beams.
An Author of Valuable Publications
Returning to Rankine’s biography, it is important to note his association with the Royal Society of Edinburgh. He was elected a Fellow in 1850 and served as its Vice-President from 1871 to 1872.
In 1855, he became the Regius Professor of Civil Engineering and Mechanics at the University of Glasgow. While holding this position, Rankine wrote numerous publications on civil engineering topics that became immensely popular among both theorists and practitioners.
Legacy and Final Years
Thus, William Rankine is remembered in history as a brilliant scientist and the developer of important theories. His contribution to the development and refinement of thermodynamics is undeniable and of enormous value. Each of his papers was a sensation, proving or disproving the existence of certain phenomena. This, in turn, enabled Rankine’s successors to achieve new, equally stunning results.
The scientist’s life came to an end on 24 December 1872, Christmas Eve. The talented scientist was only 52 years old.