From Eye magazine:

End papers from Penrose’s Pictorial Annual, 1899, letterpress. This edition of the Annual devoted considerable space to the then emerging three-colour process. Among the articles was ‘Six colours from three. An object lesson for the printer’ for which the end papers served as illustrations. They demonstrated the range of colours generated by the three process inks, while simultaneously functioning as backgrounds for companies advertising relevant expertise.

The article’s author was justifiably pleased with the idea and its outcome: ‘To the purely artistic mind, the result shown on these end papers may appear crude and perhaps vulgar, but to the thousands of printers throughout the country who are not familiar with the subject, and who find it difficult to understand, we think this simple object lesson will explain more eloquently than the most elaborate supplement the powers of the three-colour process’

The endpapers advertise the the Measured Colour Filters by Sanger-Shepherd, an emerging company in the field of color photography, and the services of Carl Hentschel, Ltd. Founded by Carl Hentschel (1864–1930), inventor of the Hentschel-Colortype process, this reproduction firm “produced engravings for numerous forms of printed media”.

The largest words are set in Columbus, with its distinctive curly forms for C and O. It’s paired with De Vinne (“Sanger-Shepherd”, “Penrose & Co.” (with alternate S), “Fleet Street” etc.) and the related Heyer (“Photo-Engravers”). “Carl Hentschel Colortype Process” uses a version of Regina-Kursiv.