Steve,
Contact the following private dealers/gallerists (they handle 19th Century photography, in addition to Modern and Contemporary Masters):
Allan Klotz Gallery (expert on historical and vintage photography)
511 West 25th Street, Suite 701
New York, NY 10001
(212) 741-4764
Robert Koch Gallery
49 Geary Street, 5th Floor
San Francisco, CA 94108
(415) 421-0122
Fraenkel Gallery
49 Geary Street, 4th Floor
San Francisco, CA 94108
(415) 981-2661
The above-mentioned will give you a realistic market valuation. If you're solely looking for value in a historical context, all three will be able to recommend appropriate resources, among them, historians and museum personnel. Experts in the photography departments of Christie's and Sotheby's auction houses should be of help, as well.
Center for Photography in Houston -- should be able to steer you toward local conservators, to ascertain the condition of your prints.
Looks like a great find. Good luck!
Andrew