Thanks to Sara Stevenson for discovering the following new information.

In the November 1844 issue of The Art-Union, Thomas Willats placed the following advertisement:

“Photography . . . Energiatype, photogenic and iodized paper, and every apparatus or chemical preparation required in Photography may be obtained, upon the most moderate terms, of Thomas Willats, Optician, 98, Cheapside, for many years with E. Palmer, Newgate-street, who has retired from the business. Lists of prices forwarded gratis, and full instruction given to purchasers. ‘We have examined some of the pictures executed by means of Mr. Willats’s improved camera, and find them most perfect, even to the minutest detail. The camera is of superior value, as it can be adjusted with greet facility and certainty, and obviates the trouble in the old instrument.’”

Horne, Thornthwaite, and Wood became the successors to Palmer’s shop and Thomas Willats set up at a fashionable Cheapside address where he not only sold equipment but also began publishing a series of scientific manuals, the first in 1844 titled Plain Directions for Obtaining Photographic Pictures by the Calotype, Energiatype, and other processes on paper… . By 1845, his brother Richard Willats had joined the firm, now known as “T. & R. Willats”. New editions and revisions of the first manual were issued in 1845, 1846, 1847, 1850, 1851, 1852, 1853, 1855, and 1860.

A copy of the first edition of Thomas Willats’s publication was collected by Robert Ormes Dougan (1904-1999) and came to Princeton University Library when a small portion of his collection was acquired by Peter Bunnell. (See catalogue: The Robert O. Dougan Collection of historical photographs and photographic literature at Princeton by Peter C. Bunnell, 1983). Princeton, Oxford, and Cambridge hold the only three institutional copies of this important early document.

Since it is so rare, here is a copy:

Plain directions for obtaining photographic pictures by the calotype and energiatype processes (London: T. Willats, 1844). Provenance: Robert O. Dougan Collection of Historical Photographs and Photographic Literature at Princeton. Marquand Library (SAX): Rare Books XB87.0057

**In 1897, daguerreotypes of Thomas Willats and Richard Willats were exhibited in London. If anyone knows the present location of these, please let us know.