In 1838 English printer and publisher Charles Knight received British patent No. 7673 for "Improvements in the Process and in the Apparatus used in the Production of Coloured Impressions on Paper, Vellum, Parchment, and Pasteboard by Surface Printing." Knight called his color printing process "illuminated printing," and invented it for the economical printing of colored pictures, maps, and drawings.
"At first only four colours were contemplated, and by some ingenious mechanism he contrived that they should all be applied in the course of a single passage of the sheet through the press, which was operated by hand. Knight, like Savage, had a decided preference for a press of the 'Ruthven' type, in which the platen was normally at the back, but was brought over the forme by means of two springs, which 'gave' to the pull, but resumed their ordinary position when the bar was released. Knight fitted the machine, in place of the usual bed, with a polygonal revolving frame, or, as he called it, 'prism' (attached to a rising table), each face of which, carrying a colour block, was applied in sucession to the sheet as the frame revolved. In an alternative method, the frame with the blocks on it revolved ona sort of turn-table, placed on the bed of the press; whilst in a third, the tympan, with the sheet attached, was carried from block to block. It will be remembered that this idea of printing several colours at one operation of the press had been to some extent anticpated by Lalleman, at Paris, two centuries earlier. The specification also describes an apparatus in which the colour blocks were on beds, hinged to the sides of a square table, and turned backward to be inked by hand, and down again for the impression. The process was in regular operation in 1839, as the Quarterly Review for December in that year contains an article, headed "The Printer's Devil," in which is a description of Clowes' printing establishment, and a fairly lengthy reference to Knight's colour-printing method, which the writer of the article in question saw at work, in connection with the production of "Patent Illuminated Maps." He describes the printing apparatus as resembling a square box, each of the four sides of which carried a printing plate, for blue, yellow, red and black respectively, which were applied to the sheet in the ordered named, the last having the letterpress matter for the names of places,etc. The tints being partly blended on the paper, three more were furnished in that way, i.e. the yellow and the red gave orange, the yellow and blue green, and so on, there being thus seven colours in all" (Burch, Colour Printing and Colour Printers  141-43).
In 1839 Knight issued a couple of examples of "illuminated printing" in his publication of Jackson's A Treatise on Wood Engraving Historical and Practical. One of my copies contains at p. 715 as called for in the List of Illustrations, "A Café in Constantinople, and a Design for a Pattern, two of "Mr. Knight's Patent Illuminated Prints." My other copy substitutes Knight's "Patent Illuminated Map" of Ancient Jerusalem, a double-page tip-in, for the Constantinople scene. Both copies also contain a more finely detailed Baxter print of "Parsonage at Ovingham" at p. 713.
In 1840 Knight published a series of his "illuminated maps" in Hughes, The Illuminated Atlas of Scripture Geography: A Series of Maps Delineating the Physical and Historical Features in the Geography of Palestine and the Adjacent Countries accompanyied with An Explanatory Notice of Each Map. . . This small 4to contained 20 double-page maps color-printed by Knight's process. Regarding the maps, the work stated on p. 6:
"Lastly, we have to explain in a few words the peculiarities which distinguish the appearance of these Maps from any which have hitherto been published. These are, —1st, That, by a novel method of printing, the various divisions of the countries are covered with distinct colours, so that the boundaries are clearly perceived at the first view; and 2nd, That the mountains, instead of being, as in maps engraved in the usual manner, indicated by black lines, are in white, distinctly and prominently relieved by the coloured ground. In the best engraved maps a serious imperfection has always been felt to result from the names and the hills being alike printed in black, in consequence of which, either names are obscured by the hills, or the hills must be omitted in order to allow of the names being read. This renders them exceedingly difficult of reference; and it may be generally remarked of engraved maps, that in proportion as the physical features of country are fully and correctly delineated, so do the names and boundaries become obscure and unintelligble. In the ordinary process of map-engraving, the evil complained of appears unavoidable; but this is no longer the case when a different medium is used for conveying each part of the requisite information. By the method adopted in this series of Maps, the physical features of the countries—their hills and valleys—their lakes and streams—are clearly delinieated, without in the least interfering with the exhibition of names and places; while their various divisions, distinguished by colours, are presented at once and distinctly to the eye of the student. They will thus, it is believed, be found better calculated than any hitherto published to serve the important purposes of School and Home Education."