Page:Dictionary of National Biography volume 62.djvu/320

 Royal Society in 1828 awarded Wollaston a royal medal for his work. Wollaston himself constructed platinum vessels for the concentration of sulphuric acid for vitriol makers. It was from this source and from royalties on processes contrived by him for various other manufacturers that he accumulated his considerable fortune (English Cyclopædia).

As an inventor of optical apparatus Wollaston ranks very high. In 1802 he described the total-reflection method for the measurement of refractivity, which is applicable to opaque as well as to transparent bodies, and has since been extensively developed by Pulfrich and Abbe; and it was in the same paper that he drew attention to the dark lines (since known as Fraunhofer lines) in the solar spectrum, which he considered, however, as merely serving to separate the ‘four colours’ of the spectrum from one another. In 1803 he invented ‘periscopic’ spectacles, useful when oblique vision is necessary; and in 1807 he patented the camera lucida (Nicholson's Journal, xvii. 1), an instrument subsequently improved by Amici and others, which has proved of the greatest value in surveying, in copying drawings, and in drawing objects under the microscope. It was the desire to fix the image of the camera lucida that led William Henry Fox Talbot [q. v.] to his discoveries in photography. In 1809 Wollaston invented the reflecting goniometer, which first rendered possible the exact measurement of crystals and determination of minerals, and which was till recently used in its original form. In 1812 he described a periscopic camera obscura and microscope, combining specially distinct vision with a wide aperture. In 1820, in a paper ‘On the Method of cutting Rock Crystals for Micrometers,’ he described the double-image prism named after him, which was an improvement on that invented by Abbé Alexis Marie Rochon, who had kept its construction secret. In a posthumous paper published in 1829 was described a microscopic doublet still used in its original form and as the objective of the compound microscope.

Wollaston also contributed to theoretical optics. He adopted the wave-theory of light, which at the beginning of the century was revived and applied to the explanation of interference phenomena by his friend Thomas Young (1773–1829) [q.v.] (see letter from Wollaston in Life of Young, p. 374); and in 1802 he showed that measurements of the refractive index of Iceland spar in different directions agreed with Christian Huygens's construction for the wave-surface (1690). This brought him a bitter and contemptuous criticism from Brougham in the ‘Edinburgh Review’ (1803, ii. 99).

In 1801 Wollaston established the important physical principle that ‘galvanic’ and ‘frictional’ electricity are of the same nature, and stated that the action of the voltaic cell was due to the oxidation of the zinc. In April 1821 he noticed that there was ‘a power … acting circumferentially round’ the axis of a wire carrying a current, and tried in Davy's laboratory to make such a wire revolve on its axis. His unsuccessful experiment led to a grave charge of plagiarism being made subsequently against Michael Faraday [q. v.]; but Wollaston, says Faraday, behaved with a ‘kindness and liberality’ ‘which has been constant throughout the affair,’ and the charge was ultimately acknowledged to be unfounded. Henry Warburton [q. v.], one of Wollaston's most intimate friends, played a part in the affair (, Life … of Faraday, 1870, i. 338–53).

Among Wollaston's other papers may be mentioned those ‘On Percussion’ (1816) (in which he adopts the Leibnitzian definition of ‘mechanic force’ as opposed to the Cartesian); ‘On Chemical Effects of Light’ (1804); that on ‘Fairy-Rings’ (in which he fully explained the rôle of fungi in these phenomena) (1807); ‘On a Method of Drawing Extremely Fine Wires’ (still used in the construction of the bolometer) (Phil. Trans. 1813, p. 114); ‘On the Finite Extent of the Atmosphere’ (ib. 1822, p. 89); ‘On a Method of comparing the Light of the Sun with that of the Fixed Stars’ (ib. 1829, p. 19).

Wollaston served with Young and Henry Kater [q. v.] as commissioner of the Royal Society on the board of longitude from its reconstitution in 1818 until the abolition in 1828 of this ‘only ostensible link which connected the cultivation of science with the government of the country.’ In 1814 Wollaston suggested in evidence before a committee of the House of Commons the replacement of the various gallons then in use by a gallon containing ten pounds of water at a given temperature. This measure, known as the ‘imperial gallon,’ was adopted in the ‘Weights and Measures Act of 1824.’ He was a member of the royal commission on weights and measures that rejected the adoption of the decimal system of weights and measures (Report of Commission, 24 June 1819).

The majority of Wollaston's papers are short and apt in expression. ‘The most singular characteristic of Wollaston's mind