SPECIAL APPLIANCES.
There are not many special appliances made for this kind of work, but those are important. FirSt comes the stand. The ordinary tripod is frequently too short for this purpose. A stand capable of raising the camera at least 5 ft. is necessary. The best plan is to provide two stands, one rising to 6 ft. and the other to 4 ft. 6 in., for the taller apparatus will be found extremely awkward when used only :3 or 4 ft. from the floor, as may be required. Very often the camera may need to be raised 10 ft. or even higher, but in this case it should be screwed to the top of a pair of steps or on a plank placed across some high trestles, a second plank being placed below for the operator to stand upon. The advantage of the latter method lies in being able to move the camera easily in a direction parallel with the object. A source of considerable trouble with stands is their liability to slip, and, unless sonic method of fixing to the floor is available, it is best to brace the legs together with a cord or strap, and in some cases even to weight it as shown by Fig. 790. Perhaps the most important
piece of apparatus is the tilting table.
This is intended for employment when floor stones or carved ceilings have to be dealt with. There are several kinds now in the market (see, for example, Fig. 113, p. 54), but a simple appliance may easily be made by hinging two boards together, as shown by Fig. 791, and fixing at a proper distance so as to bring the two to see at once whether the frame or the base requires alteration. The plumb indi cator should be attached to the side of the back frame. A reversing prism or a mirror inclined at an angle of 45° may be used instead of a tilting board if desired. For small work, with a light camera, the tilting stand shown by Fig. 792 is very suitable.