We are all familiar with the lists of ingredients on food packets, which often also tell the food value in Kilojoules. They are named after James Joule, born on Christmas eve 1818 into a well off brewing family in Salford, who worked on the relationship of work, heat and energy and made a huge contribution to science.
Joule had no formal education, but his father persuaded John Dalton, then in his fifties to give James and his brother three lessons each week in his rooms at the Literary and Philosophical Society of Manchester. Joule wrote, ‘It was from this instruction that I first formed a desire to increase my knowledge by original researches.’ James’s mother died when he was sixteen and three years later James turned one of the rooms of his father’s house into a laboratory. He experimented with heat, work and energy without any public recognition, but said that ‘The study of nature and her laws is essentially a holy undertaking.’ His experiments proved that heat produced by friction is directly equivalent to the work involved.
It was his friendship with William Thomson which ended his obscurity. He had met him at a British Association for Science meeting in Oxford. He described their friendship as ‘most valuable to me in every respect, for I had one whose soul was occupied with the love of truth and whose unprejudiced mind immediately entered into views which at that time had taken no hold whatsoever in the scientific world.’ In 1850 Joule was made a member of the Royal Society, a year in which he and his wife Amelia had their first child. Even this happy event stirred his thoughts of science; he wrote to Thompson, ‘If, as I hope, you will make it convenient to be at the Christening, and stand as godfather, we might at the same time settle the question of heat and cold from air rushing through an orifice.’ Their work on this led to the principles on which refrigeration is still based. In 1854 his child and his wife died. He wrote, ‘I have lost this, my dearest earthly friend. How the loss of such a parent can be replaced to my dear children I cannot tell. I must trust in the Almighty to care for them and to direct me in their upbringing. It is a great satisfaction to reflect that her death had no terrors, reposing as she did in the merits of her Saviour as her title to her heavenly inheritance.’
James himself died, with many honours, on 11th October, 1889.