266 National Geographic Magazine. 



extent, also, on the use to which the model is to be put. The 

 plain cast is sometimes used, drainage, lettering, etc., being put 

 directly upon it. This has the advantage of preserving all the 

 detail that comes from the mould, but it has also the disadvan- 

 tage of a surface easily soiled and impossible to clean. If the 

 model is to be photographed, the surface should be nearly white — 

 in our practice we use a small amount of yellow with the white. 

 This yellow is hardly appreciable by the eye, but its effect upon 

 the photographic negative is quite marked. Yellow becomes 

 grey in a photograph, and, in a photograph of a model colored as 

 described, a grey tint is given to the whole surface. The high 

 lights are not pure white, and there is no harsh contrast between 

 light and shade. There is another point of great importance in 

 photographing models : the surface should have a dead finish — 

 that is, should have no gloss, or, at most, should have only what 

 is known among painters as an egg-shell gloss. It is almost 

 impossible satisfactorily to photograph a model that has a shiny 

 surface. Any portion of a model that it is desired to separate 

 from the rest should be painted a different color — the water, for 

 example, should be painted a light blue ; not a blue composed of 

 indigo, however, or any of the grey blues, as these produce in 

 the photograph a dead grey, and are not pleasant to the eye. 

 The most satisfactory color that we have used is a mixture of 

 cobalt — the purest of the blues — with Antwerp blue — which is 

 quite green — and white. This gives a color that is pleasant to 

 the eye, has the retreating quality to perfection, and photographs 

 well. 



Models intended for exhibition as such should be painted real- 

 istically. There is room here for an immense improvement in 

 the usual practice, which is to paint the model either in some 

 conventional scheme of light and shade, or else to put a single flat 

 tint upon it. If the model is to be colored conventionally it is, 

 in my opinion, much better to use a flat tint, light in tone, and 

 with a dead surface. The use of a variety of colors upon the 

 face of a model interferes materially with the relief, especially 

 if the relief is finely modeled. For this reason models colored to 

 indicate geologic formations should always be accompanied by 

 duplicates representing topography only, colored realistically, if 

 possible, and without lettering. Well-defined lines other than 

 those pertaining to the model itself, such, for example, as those 

 used to define the boundaries of geologic formations, should not 



