John Henry Pepper

John Henry "Professor" Pepper (17 June 1821 – 25 March 1900) was a British scientist and inventor who toured the English-speaking world with his scientific demonstrations. He entertained the public, royalty, and fellow scientists with a wide range of technological innovations. He is primarily remembered for developing the projection technique known as Pepper's ghost, building a large-scale version of the concept by Henry Dircks, which Pepper first publicly demonstrated during an 1862 Christmas Eve theatrical production of the Charles Dickens novella, The Haunted Man and the Ghost's Bargain, causing a sensation among those in attendance at the Regent Street theatre in London.

Pepper also oversaw the introduction of evening lectures at the Royal Polytechnic Institution (University of Westminster) and wrote several important science education books, one of which is regarded as a significant step towards the understanding of continental drift. While in Australia he tried unsuccessfully to make it rain using electrical conduction and large explosions.

Pepper was born in Westminster, London and educated at King's College School. While there he became interested in chemistry, as taught by John Thomas Cooper. Cooper acted as a mentor to Pepper, who went on to become an assistant lecturer at the Grainger School of Medicine at the age of 19. In around 1843 he was elected a Fellow of the Chemical Society.

Pepper delivered his first lecture at the Royal Polytechnic Institution in 1847 and went on to take the role of analytical chemist and lecturer the year after. By the early 1850s he was its director. He introduced a series of evening classes covering educational and trade topics, and lectured by invitation at some of the most prestigious schools across England, including Eton, Harrow, and Haileybury. Amongst the students at Eton was Quintin Hogg, who would go on to become a philanthropist and benefactor of the Royal Polytechnic Institution. Pepper also lectured in New York and Australia. Pepper became a highly regarded science performer and often went by the name "Professor Pepper". He regularly demonstrated a range of scientific and technological innovations with the intention of entertaining and educating the audience about how they worked. He used many of these to expose the trickery behind deceptive magic, and became famous for a new technique now known as "Pepper's ghost".

Liverpudlian engineer Henry Dircks is believed to have devised a method of projecting an actor onto a stage using a sheet of glass and a clever use of lighting, calling the technique "Dircksian Phantasmagoria". The actor would then have an ethereal, ghost-like appearance while seemingly able to perform alongside other actors. Pepper saw the concept and replicated it on a larger scale, taking out a joint patent with Dircks. Pepper debuted his creation with a Christmas Eve production of the Charles Dickens play The Haunted Man in 1862 and Dircks signed over all financial rights to Pepper. Through this the effect became known as "Pepper's ghost", much to the frustration of Dircks, and though Pepper insisted that Dircks should have a share of the credit, the technique is still named after the man who popularised it. Some reports have suggested that, at the time, Pepper claimed to have developed the technique after reading the 1831 book Recreative Memoirs by famed showman Étienne-Gaspard Robert.

Pepper's demonstrations of "the ghost effect" were received with amazement by the general public while intriguing his fellow scientists. People returned to the theatre repeatedly in an attempt to work out the method being used; famed physicist Michael Faraday eventually gave up and requested an explanation.

Pepper wrote eleven popular science books, starting with his first publications in the 1850s. 1861's The Playbook of Metals, built upon the work of Antonio Snider-Pellegrini and is regarded as an important step in the understanding of continental drift. The books became so successful, particularly The Boy's Playbook of Science, that they could be found in secondary schools throughout the United Kingdom, and some American reprints became prescribed school texts in Pennsylvania and Brooklyn.

Pepper was fascinated with electricity and light. In 1863 he illuminated Trafalgar Square and St. Paul's Cathedral to celebrate the marriage of Albert Edward, Prince of Wales, and Alexandra of Denmark. He achieved this using a variation of the arc lamp. On 21 December 1867 at a banquet of "noblemen and scientific gentlemen" Pepper arranged for a telegram to be sent between Arthur Wellesley, 2nd Duke of Wellington and Andrew Johnson, President of the United States who was in Washington at the time. The message took just under 10 minutes to arrive in the United States with a reply coming in after around 20 minutes. This transmission was hailed as a significant achievement for science.