I recently obtained a Reversible Back Graflex, which dates between 1901 and 1905. It definately has some unique features when comparing it to a Graflex from the Eastman Kodak and forward times. I have searched and searched for the serial number and cannot locate it. I was told that it is on the hood door...on the right side as you are looking at the front of the camera. The underside of the hood door (larger door on top) differs from later Graflex cameras in that it is covered with leather. The curved eye cup/viewer is fixed to the top of the door, requiring the removal of several small wood screws to remove it. Even then it has a leather that is glued to the door and would take a lot of TLC to remove. I did take out the screws and was able to pull the eye cup slightly away from the hood door and discovered that a Serial number did not exist behind the hood. I have looked at it over and over!

So...is there another place that Folmer& Schwing stamped serial numbers?

On the 1910 RB Auto that I own it is embossed into the metal band that is around the focus hood opening. The hood door is hinged at the front of the camera and the s/n is in the rear top of the metal. It is so obscure that looking straight into it it cannot be seen. Shine light at a 45 degree angle to to opening and rotate 5 to 10 degrees while checking the edge.
Charles