PHOTOGRAPHY. 
55 
elevated objects in correct drawing when the instrument is level. Sir 
Martin Conway advises that “ the angles of the double backs of this camera 
should be made stronger than they usually are. The shutter spring 
should be carefully tested for quality before starting, and a duplicate 
spring taken, which the traveller should learn to adjust/' 
In addition, a light tripod stand should be taken for supporting the 
camera when longer exposures are required than can be given in the hand. 
A very satisfactory compromise has been adopted by Captain Abney 
between using the camera in the hand and on a tripod. He rests the 
camera on top of a walking stick when making hand exposures, with the 
result that he overcomes all tremor caused by pulsation, and so secures 
photographs full of sharp detail. There are a number of excellent hand- 
cameras made. 
2. Slides for holding the sensitive plates. —These are frames which slide 
into the back of the camera in place of the focussing-glass, which is 
removed. They each hold, as in the twin lens camera, two sensitive plates 
back to back, with an opaque partition between them, so that a dozen 
plates will require six slides or “ double backs." 
In order to secure the camera against the admission of light when the 
plate is being exposed, cover the camera entirely with the focussing-cloth, 
leaving the lens free, and pull out the shutters of the slides under the cloth. 
3. A focussing-cloth. —This is used for keeping out the light while 
focussing, being thrown over the camera and the head of the operator. 
It is generally made of black velvet, but waterproof sheeting is much 
better. It should have rings sewn on to one edge, or some arrangement 
by which it may be attached to the camera so as not to be blown away. 
4. Camera-stand— There are many varieties of tripod stands, with legs 
either folding or sliding into a small compass. For mountainous country 
it is of great advantage to have a stand with sliding legs, as they can be 
readily altered in length so as to stand firmly on slopes or rocky ground. 
Kennett's is a good form of sliding stand, and is made in two or three 
different sizes. The smallest size, weighing about 3 lbs., and measuring 
33 in. long when closed, and standing about 4 ft. 6 in. high, is steady 
enough to support a x 5 camera without perceptible vibration in a 
moderate wind. That of Hunter & Sands is another very good pattern. 
5. A small circular cup level, let into the wood of the camera, for level¬ 
ling the camera on the tripod. 
