224 The Field Naturalist' s Quarterly Aug. 



photographic, sense) or of rock specimens, careful Hghting 

 is important. In the former case the position of the subject 

 should be studied and the time of day so selected that the 

 sun is partially on one side and not directly behind the 

 camera. In archaeological work, too, this point is often 

 of great importance, as a faint inscription which direct 

 lighting makes almost invisible will often show up quite 

 plainly if the sun's rays strike on it very much on one side. 

 In such a case there is often only one hour of the day at 

 which the work can be done to best advantage. The archi- 

 tectural student will probably do without a "wide-angle" 

 lens for some time, as he will not want to compete with 

 the professional in producing those views of the whole of 

 a church or cathedral so much in evidence at the stationer's 

 shop, but will want to secure records of details of work, such 

 as windows, fonts, misereres, churchyard crosses, tombs, 

 and brasses. Here the long extension to the camera will 

 be found invaluable. There is one invaluable rule for work 

 of this kind where upright lines are involved. It is to 

 keep the back of the camera plumb upright. If the rising 

 front will not secure enough of the top of the subject and 

 the camera has to be tilted, the swing back of the camera 

 is brought into play to secure this all-important uprightness 

 of the plate. 



Although the subject of exposure is an all-important one, 

 I do not propose to add anything to my reference in the 

 May number, except to note that an exposure must be 

 sufficiently long to render on the sensitive plate all detail 

 in the worst lighted (shadow) part of the subject, and that 

 to avoid certain defects it must not very greatly exceed 

 this minimum. 



As regards development, I am free to give a few hints 

 on general principles. Just as in exposing a plate ren- 

 dering of detail only need be considered, so in developing 

 it the question of contrast between the highest and lowest 

 tones is the one point to consider. And the rule is a simple 

 one. Too short a time for development secures only a 

 feeble contrast in the finished photograph, which is flat and 

 grey. On the other hand, if the plate is left in the developer 

 for too long a time, the contrast between the tones is too 



