Roget-Thesaurus & Slide Rule

And founder of the Portico Library

Portico Library Reading Room-Manchester

Peter Mark Roget was a British physician and lexicographer. He compiled the thesaurus which bears his name, Rogets’s Thesaurus.

Peter Mark Roget (1779–1869) from Medical Portrait Gallery by Thomas Pettigrew

In 1815 Roget invented the log log scale to calculate roots and powers to any number or fraction thereof. ¹ He was a Fellow of the Royal Society where he read a paper about a peculiar optical illusion in 1824, regarded as the origin of the persistence of vision

He was founding secretary of The Portico Library in Manchester.²

He published works on tuberculosis and on the effects of nitrous oxide, known as 'laughing gas', then used as an anaesthetic.³ He is on Munk’s Roll at the Royal College of Physicians.⁴

He is most famous for Roget’s Thesaurus. (1852). The schema of classes and their subdivisions is based on the philosophical work of Leibniz.

Roget described his Thesaurus in the foreword to the first edition:

It is now nearly fifty years since I first projected a system of verbal classification similar to that on which the present work is founded. Conceiving that such a compilation might help to supply my own deficiencies, I had, in the year 1805, completed a classed catalogue of words on a small scale, but on the same principle, and nearly in the same form, as the Thesaurus now published.

We know what was in his personal library from the Sotheby’s catalog when the library was sold.⁵ He wrote for the Encyclopedia Britannica. He was a founder of the Society for the Diffusion of Useful Knowledge.⁶

1. Oughtred Society. Dedicated to the History and Preservation of Slide Rules. Slide Rule History.

2. The Portico Library. The Portico Library was established by 400 founding subscribers in 1806, during Manchester’s emergence as ‘the first modern city’. Built with wealth derived from the Industrial Revolution, British empire-building, and colonial expansion, the Library amassed a collection that reflects the innovations, but also the exclusions and inequities of its time.

3. Kendall, Joshua (2008). The Man Who Made Lists: love, death, madness, and the creation of "Roget's Thesaurus". New York: G. P. Putnam's Sons. C-Span has an interview with Kendall, The Man Who Made Lists.

4. Peter Mark Roget. b.18 January 1779 d.12 September 1869. Munk’s Roll at the Royal College of Physicians.

5. Emblen, D.L. (1969). “The Library of Peter Mark Roget.” The Book Collector 18 no 4 (winter): 449-469.

6. Harold Smith. The Society for the Diffusion of Useful Knowledge, 1826–1846: A Social and Bibliographical Evaluation. Halifax, N.S.: Dalhousie University Press, 1974.