Again, should a drawing, map. or other such design require to be copied, it can be easily accomplished by reversing the position just described and pointing the lens downwards towards the floor, where the object is spread out between the legs of the tripod.
Before describing the various operations involved in producing a photographic picture, we may call attention to one more very necessary piece of apparatus, namely, the red lamp. It is a fortunate thing for photography that the chemicals employed, although so sensitive to white light that a picture can be obtained in the smallest fraction of a second of time, are insensitive, or nearly so, to red rays of light. Were it otherwise, photography would be almost an impossibility - unless men were gifted with the power of seeing in darkness. As it is, the operator conducts all his work - except the business of actually taking the picture - by red light. The professional has, of course, his dark room, in which the daylight is filtered through some kind of ruby medium. But to carry on work at night - or away from home, when plates have to be changed, and even developed in out-of-the-way cupboards or cellars - a red lamp is a sine qua non. The form of lamp shown at page 121 presents a great many advantages. It possesses a powerful paraffin lamp, so arranged that the oil receptacle is isolated from the flame, and cannot get heated. It has a sliding door at the back, so constructed with guarded loopholes that plenty of air can get in and out, but no ray of white light can steal outside. In front are two large panes of ruby glass.
A less expensive form of lamp is made (this is the lamp shown in the set at page 121), in which two sides of the lamp are of metal, and the third of red glass. The metal sides are hinged together so that they will fold up for travelling, with the ruby glass protected from fracture by lying between them. Top and bottom triangular pieces - one forming a candle holder, and the other a chimney - complete this clever little arrangement.
We may in this connection also notice a portable tent which has been very lately introduced, and which may rightly be regarded as the latest novelty in the world of photography. It is shaped like an umbrella, and is known as the "Patent Eclipse Ruby Tent." Like an umbrella, it folds up in very small space, 30 x 3 inches, and can be set up for plate changing or developing purposes as easily as its well-known prototype. It is shown at page 115. Made of two thicknesses of material, canary color under ruby or black, no light can enter it except through its window of ruby fabric. It is unnecessary to use a ruby lamp. Daylight, or the light from an ordinary lamp or candle placed outside the tent, shining through the ruby and canary materials of which it is made amply illuminates the interior. The head and hands are introduced so that the operator, either at home or abroad, sitting in a chair, can conveniently watch the progress of his work whilst the tent rests on the table. For the summer tourist such a tent is indispensable; but for general use it represents a distinct gain to the photographer, being very preferable to the stuffy cupboards often employed as makeshifts for dark rooms by beginners.