CHANGING BAGS AND BOXES A changing bag is a device to allow of reload ing dark-slides or sheaths without the necessity for a dark-room. It is generally a bag of several thicknesses of black and red material, provided with sleeves which tighten round the arms by means of elastic, so that the hands are inside the bag. In some forms the changing has to be effected by the sense of touch alone ; in others there is an eye-piece to fit on the face so that the interior of the bag can be seen, light being admitted through a panel of red fabric or cellu loid in one side of the bag. The utility of such a bag as a makeshift dark-room is obvious.
A changing box is a magazine holding plates in sheaths, and is generally detachable from the camera. An exposed plate can be moved from the front to the back, or an unexposed plate taken from the back and placed in front of the one last exposed. The usual method of accom
plishing this is to raise the plate into a bag of flexible leather and place it in position by hand, but in some cases the transfer is made mechanic ally. The front of the changing box is fitted with a draw shutter, which is opened for expo sure and closed when the box is to be removed from the camera. The back of the box can be opened for the removal of exposed plates and for reloading the sheaths. Hence there is some advantage in those types in which the exposed plates find their way to the back of the box, as they may be removed without disturbing unused plates. Many boxes are constructed to take cut films instead of plates, their capacity thus being doubled. Obviously the number of plates or films available may be increased by the use of additional changing boxes. (See also " Daylight Changing.")