David Brewster

British physicist (1781–1868)

Brewster, who was born in Jedburgh, Scotland, started by studying for the ministry at Edinburgh University but, after completing the course, he abandoned the Church for science. He earned his living by editing various journals and spent much time popularizing science.

Brewster published almost 300 papers, mainly concerning optical measurements. He was an early worker in spectroscopy, obtaining (1832) spectra of gases and of colored glass. His most famous work was on the polarization of light. In 1813 he discovered Brewster's law, which states that if a beam of light is split into a reflected ray and a refracted ray at a glass surface, then they are polarized, and the polarization is complete when the two rays are at right angles. The angle of incidence at which this occurs is called the Brewster angle. He is also known for his invention, in 1816, of the kaleidoscope.

Brewster was knighted in 1832. From 1859 he was principal of Edinburgh University.

Brewster, David (1781-1868), Scottish physicist, born in Jedburgh and educated there and at Edinburgh University, after which he took a job as a tutor. Although trained for the Church, he was unable to preach—or indeed, to teach—because of a nervous reaction to public speaking. Instead, to fund his scientific work, he took to scientific journalism, and in the meantime laid practical foundations for much of the optical work undertaken during the 19th century. Because he never fully accepted the wave theory of light and because he outlived most of his scientific contemporaries, Brewster ultimately found his experimental work marginalized. Many of his achievements were attributed to others.

Brewster was involved in photography from its very beginnings: he stayed with Talbot in 1836, and although Talbot did not publish his findings until 1839, Brewster was sent examples of his work from an early stage. Brewster's correspondence with Talbot meant that St Andrews was the first place outside England that the calotype was practised; and it was on Brewster's advice that Talbot did not patent his invention outside England. However, although Brewster collected photographic prints and wrote fairly extensively on the subject, he apparently lacked the time to practise the new photographic art much himself. He introduced the artist D. O. Hill to the calotypist Robert Adamson in 1843. In 1849 Brewster announced a successful lenticular stereoscope for viewing stereo- daguerreotypes, a version of which was presented to Queen Victoria in 1851.

— A. D. Morrison-Low

Bibliography

• Morrison-Low, A. D., and Christie, J. R. R. (eds.), ‘Martyr of Science’: Sir David Brewster 1781-1868 (1984).
• Morrison-Low, A. D., ‘Sir David Brewster and Photography’, Review of Scottish Culture, 4 (1988)

Brewster, Sir David, 1781–1868, Scottish physicist and natural philosopher. He is noted especially for his research into the polarization of light (the invention of the kaleidoscope was one result of his studies). He improved the spectroscope and persuaded the British government to adopt his dioptric system of lighthouse illumination. For 21 years Brewster was principal of the United College of St. Salvator and St. Leonard, in St. Andrews, Scotland, and in 1859 he became principal of the Univ. of Edinburgh. Included in his numerous writings are A Treatise on Optics (1831) and Memoirs of the Life, Writings, and Discoveries of Sir Isaac Newton (1855).

(1781-1868)

Famous nineteenth-century scientist whose brief investigation of Spiritualism in 1855 led to bitter public acrimony. Brewster was born on December 11, 1781, in Jedburgh, Scotland. His formal education was as a divinity student at the University of Edinburgh, but while there, he maintained and interest in physical science which he had become interested in as a child. The controversy was sparked when Brewster attended a séance with a Lord Brougham in Cox's Hotel in Jermyn Street in London's West End. The medium was D. D. Home, to whom Brewster was introduced by Lord Brougham. Reportedly both were deeply impressed. Home subsequently wrote to a friend in America, describing the visit and stating that they were unable to account for the phenomena by natural means. The letter, published and commented upon in America, found its way into the London press. Sir David Brewster who, in the meantime, had had another séance at Ealing in the house of Mr. Rymer, a London solicitor, promptly wrote to the Morning Advertiser, forcefully disclaiming all belief in Spiritualism and ascribing all the phenomena to imposture. His letter ended: "I saw enough to satisfy myself that they could all be produced by human hands and feet."

A heated newspaper controversy arose. Edward W. Cox, sergeant-at-law, who was present at the séance, wrote to the Morning Advertiser, to contradict Brewster, and citing Brewster's expression of astonishment: "This upsets the philosophy of fifty years." When Brewster replied that he had not been allowed to look under the table, both Cox and the well-known author T. A. Trollope (brother of novelist Anthony Trollope) also present at the Ealing séance, contradicted him. Yet another statement, one by Benjamin Coleman, quoting Sir David Brew-ster's admission of the reality of the phenomena in private conversation, was published.

Brewster replied in an angry tone, gave a description of the sitting, and declared: "Rather than believe that spirits made the noise, I will conjecture that the raps were produced by Mr. Home's toes, and rather than believe that spirits raised the table, I will conjecture that it was done by the agency of Mr. Home's feet, which were always below it." He further said that the spirits were powerless above the table but were very active beneath a large round table with copious drapery, beneath which nobody was allowed to look. After describing how a handbell from the neighborhood of Mr. Home's feet came across and placed itself into his and afterward into Lord Brougham's hands, he concluded: "How these things were produced neither Lord Brougham nor I could say, but I conjecture that they may be produced by machinery attached to the lower extremities of Mr. Home."

Throughout this passionate controversy Lord Brougham preserved an inflexible silence. Brewster never appealed to him. D. D. Home, on the other hand, challenged Lord Brougham's testimony. This was half promised but not given. However, a conversation is recorded by Cox in his book The Mechanism of Man (1876), in which he claimed that Lord Brougham stated to him: "We were both perfectly satisfied at the time that it was no trick, and that some unknown power was in action." I said 'Well, Brewster, what do you think of it?' and he said only 'There are more things in heaven and earth, Horatio, than are dreamt of in our philosophy.' "Lord Brougham also declared that Brewster never told him that he had changed his opinion. The only reason why he himself did not pursue the investigation was that he was then deeply immersed in experiments in optical science and did not have the necessary leisure.

The late earl of Dunraven, in his preface to the original private edition of Lord Adare's records on his experiences with D. D. Home, expressed the belief that Brewster acted out of fear of ridicule. He wrote: "He was present at two séances of Mr. Home's where he stated as is affirmed on the written testimony of persons present, his impression that the phenomena were most striking and startling, and he does not appear then to have expressed any doubt of their genuineness, but he afterwards did so in an offensive manner. I mention this circumstance because I was so struck with what Sir David Brewster— with whom I was well acquainted—had himself told me, that it materially influenced me in determining to examine thorough-ly into the reality of the phenomena."

In Home's Incidents in My Life (1863), Home wrote that Brewster treated certain of his scientific contemporaries even worse than he treated Home, claiming the credit for other people's inventions. Brewster threatened a libel action but despite Home enlarging the evidence in the second edition of his book, Brewster never carried out his threat.

The final word in this public debate was uttered in 1869 when The Home Life of Sir David Brewster was published, after his death in February 1868, by his daughter, Mrs. Gordon. A note is printed from the private diary of the scientist, which narrated the phenomena he witnessed in company with Lord Brougham: "Last of all I went with Lord Brougham to a séance of the new spirit-rapper, Mr. Home, a lad of twenty, the son of a brother of the late Earl Home. He lives in Cox's Hotel, Jermyn Street; and Mr. Cox, who knows Lord Brougham, wished him to have a séance and his Lordship invited me to accompany him in order to assist in finding out the trick. We four sat down at a moderately-sized table, the structure of which we were invited to examine. In a short time the table shuddered, and a tremulous motion ran up all our arms; at our bidding these motions ceased and returned. The most unaccountable rappings were produced in various parts of the table; and the table actually rose from the ground when no hand was upon it. A larger table was produced and exhibited similar movements. A small hand-bell was then laid down with its mouth on the carpet: and, after lying for some time, it actually rang when nothing could have touched it. The bell was then placed on the other side, still upon the carpet, and it came over to me and placed itself in my hand. It did the same to Lord Brougham. These were the principal experiments. We could give no explanation of them and could not conjecture how they could be produced by any kind of mechanism."

The version from Brewster's posthumous book conflicts with his letter to the Morning Advertiser, in which Sir David expressly stated that the bell did not ring and that the table "appeared" to rise. A detailed comparison of the two statements reveals many other discrepancies. The Spectator stated in its review of Home's book, "The hero of science does not acquit himself as we could wish or expect."

There is no doubt that Brewster came out of the affair badly. He was guilty of misrepresentation when he refused to stand by his original puzzlement at the séance, and thereby was criticized for later contradicting himself. What he actually exclaimed at the time was typical of the last ditch materialist unable to believe his own senses: "Spirit is the last thing I will give in to!"

(1781–1868). Scottish physicist, born at Jedburgh and educated at Edinburgh University, of which he became vice-chancellor in 1860. He was elected a Fellow of the Royal Society in 1815 and was active in the foundation of the British Association for the Advancement of Science. His main interest was optics, and in 1816 he invented the kaleidoscope. He also improved Wheatstone's stereoscope (or at least made it more convenient, by introducing lenticular prisms rather than Wheatstone's mirrors) so allowing pairs of large pictures to be presented, one to each eye, in spite of the small interocular distance and the inability of the eyes to diverge for fusion. He also made important discoveries on the polarization of light (notably Brewster's law, that when the polarization is at a maximum the tangent of the angle of polarization — Brewster's angle — is equal to the refractive index of the reflecting medium).

(Published 1987)

— Richard L. Gregory

Bibliography
• Wade, N. J. (1984). Brewster and Wheatstone on Vision.

---

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)