Jack, thanks for reply. I did see it on Wikipedia but wasn't too sure re copyright. Oddly enough the Naval Hist Center image library appears not to have one. Also I have found their site somewhat awkward to navigate; for instance I tried to find images of Du Pont (now sourced elsewhere) and the Hartford - with limited success. However, acting on another tip-off I may try Museum of Confederacy re Thomas. Thanks again for your assistance. I will keep the site abreast of publishing dates.
Regards

Peter B