By the way, projection printing of the time was considerably more dificult considering the absence of electric light bulbs. They had to rig a system of mirrors to bring sunlight into the bellows without allowing it otherwise into the "darkroom" or, for field operations as practiced by Brady's crews, a dark tent or wagon. That's why the majority of field photos are either ambrotypes or contact prints.Carte de Visite, however, were done in a studio and intended to depect the subject (with whatever props he/she selected) to be given to friends. Many gold miners had Carte de Visite made with them holding a canvas bag with large sums of money listed on the bag. Any written material appearing in the field had to read correctly in order to make sense to the friends receiving the photos.