Beginning in 1895 and ending in 1897, English professional copperplate etcher, engraver, and printer Walter L. Colls of London issued yearly portfolios of photogravures on behalf of The Linked Ring commemorating their annual Photographic Salon which debuted in 1893. Colls, an amateur photographer himself exhibiting his own work since at least 1885, etched and printed the very fine photogravures issued with these portfolios. Significantly, Colls taught the important English photographer Peter Henry Emerson (who championed "Naturalistic Photography") how to print his own photogravures in the late 1880s. Colls also etched the printing plates for photogravures that appeared in later issues of the English series "Sun Artists" in 1891. It is known that at least three separate Photographic Salon portfolios were issued for the years 1895, 1896 and 1897.
The very first issue of Camera Notes, published by The New York Camera Club and edited by Stieglitz in October of 1897 pronounced its‘ approval of the portfolio: Colls photogravures were "capitally done," and the portfolio as a whole "one of which not only the Salon and Mr. Colls, but photography itself may be proud." (Greenough, 2002, Vol.2, p.936, footnote 23). Fully half of the images from this 1895 publication were later duplicated in issues of Camera Notes. The photogravures in Camera Notes were not only the same size as those in the salon portfolio, but also printed in similar ink colors. Stieglitz made no secret of his source for these images, crediting Colls and reviewing the portfolios in the magazine.
For an in depth overview of the Colls portfolios see: https://photoseed.com/collection/group/pictorial-photographs-a-record-of-the-photographic-salon-of-1895/
Camera Notes: The Official Organ of the Camera Club, New York: Edited by Alfred Stieglitz: New York: Vol 1., No. 2. October, 1897: p. 54
The Photogravure Process and Precedents for Camera Notes: in: Alfred Stieglitz’s Camera Notes: Christian A. Peterson: The Minneapolis Institute of Arts in association with W.W. Norton & Company, Inc.: New York | London: 1993: pp. 35-36