A Compleat System of Opticks in Four Books, Plate 57

“Plate 57” features seven illustrations to accompany Chapters XV, XVI, and XVII of Book III in A Compleat System of Opticks; these chapters describe the science behind a variety of optical and image-making machines. Figure 635 is a type of portable camera obscura for drawing made by a Mr. Scarlet, who had a shop near St. Anne’s, London, in which he performed glass grinding, lens making, and the construction of some of the optical instruments (R. Smith, A Compleat System 384). Figures 636 and 637 illustrate a binocular telescope—made by fixing two identical tubes with concave lenses parallel to each other—and an experiment conducted by Smith with a drawing compass to adjust the visual disjunction caused by the parallel tubes (R. Smith, A Compleat System 387). Figure 638 illustrates the arrangement of “plano-convex eye-glasses for each telescope,” which were also made by Mr. Scarlet in his shop (R. Smith, A Compleat System 389). Figures 639 and 642 illustrate the magic lantern, or a “Lanterna Megalographica,” with which images can be projected using a lamp through clear panes of glass or with the use of convex lenses and mirrors. Figure 639 is a simple tin magic lantern with a small flame to cast light and an adjustable tube to change the size of the projection. Figure 640 is a more complex wooden magic lantern with a larger, concave lens and reflective mirror to enhance the light. Although referenced in the text, Figure 641 (which refers to the chimney of the magic lantern) does not appear on Plate 57, nor is it mentioned in the "Errata" of the text. Figure 642 illustrates the arrangement of separate parts of the magic lantern in Figure 640: the mirror, four flames, the image on painted glass, the two lenses, the wooden stop, and the aperture (R. Smith, A Compleat System 392).

The author of this textbook on the subject of optics and optical instruments, Robert Smith (1689-1768), was the Plumian Professor of astronomy and experimental philosophy at Trinity College when the text was published in 1738 (G. Cantor, “Smith, Robert”).

Although it was published in the first half of the eighteenth century, Robert Smith’s A Compleat System of Opticks remained an important and highly regarded textbook on the subject well into the nineteenth century, thus influencing Romantic notions of optical science and the formation of vision (J. Barrow-Green, “A Corrective to the Spirit” 275). Unlike the rational recreations texts produced later in the century, Smith describes all the instruments on the illustrated plate with a full consideration of the complex optical physics and dense mathematical reasoning behind the creation of an image through an optical device. Considered the foremost book on optics of the eighteenth century, the text and illustrated plates navigate between the strictly scientific and the more fantastic uses of optical and image-making technologies. “Plate 57” in particular juxtaposes geometrical drawings of glass lens types with illustrations of magic lanterns, devices used for the creation of “some ludicrous or frightful representation, the more to divert the spectators” (Smith, A Compleat System 389). Here, Smith aligns the camera obscura (Figure 635), specifically noting its use in drawing, with two different versions of the magic lantern. Although the camera obscura was not usually used for the creation of “ludicrous or frightful” images, this arrangement highlights similar representational capabilities of the camera obscura, thus expanding the range of optical instruments that influenced Romantic vision to include the magic lantern.

Throughout the text, Smith repeatedly mentions Mr. Scarlett, an instrument maker who had a shop near St. Anne’s, London, where he performed glass grinding, lens making, and the construction of optical instruments (R. Smith, A Compleat System 384). Specifically, Smith reveals that Mr. Scarlett made the portable camera obscura for drawing featured in the illustration (Figure 635 on “Plate 57”). The emphasis on Mr. Scarlett and his shop suggests the reliance of natural philosophers and mathematicians of optics on contemporary lens-making technologies; all of the optical equipment illustrated on “Plate 57” utilized man-made glass lenses or reflective mirrors. Although “geometrical optics was relatively advanced,” as demonstrated by Smith’s mathematical explications, “the practice of making achromatic lenses was not [and] glassmakers who could manufacture optical disks larger than four inches in diameter were highly sought after” and relatively rare (M. Jackson, “Optics”). The commercial concentration of most instrument makers in the eighteenth century was surveying instruments, telescopes, and eyeglasses rather than the more specialized camera obscura, which, although often mentioned in advertisements for the instrument makers’ shops, were not as commonly produced (J. Hammond, The Camera Obscura 77-78). Thus, Smith’s early text theoretically and mathematically describes a range of optical instruments, some of which the general public would not have had easy access to until later in the eighteenth century, when the devices had a greater general impact on Romantic notions of vision and visuality.