Topographic Models. 267 



be allowed upon a model when it is desired to bring out all the 

 relief. The lettering on such models should be kept down as 

 small as possible, or wholly dispensed with. The latter is much 

 the better method. 



The cheap reproduction of models is the most important 

 problem connected with the art, and the one that is attracting 

 most attention among those engaged in it ; as, until models can 

 be reproduced cheaply, they will never have any wide distribu-' 

 tion and there will be far less incentive to the modeler. Various 

 materials have been suggested and experimented on, but nine- 

 tenths of the models that are made to-day are made of plaster of 

 Paris. Although this material was the first to be used for this 

 purpose, it has not yet been superseded. A plaster cast is heavy, 

 expensive and easily injured ; but plaster gives an accurate copy 

 of the original, retains permanently the form given it, and is 

 easily finished and repaired. The weight is an obstacle that can 

 be easily overcome. By the incorporation in the plaster of fine 

 tow, or of bagging or netting of various kinds, the cast can be 

 made very light and at the same time strong, but the expense is 

 increased rather than diminished by this method. Models made 

 in this way, however, have the advantage that when broken the 

 pieces do not fall out, they are, however, fully as liable to surface 

 injury as the other kind. The large cast in the National Museum, 

 before referred to, was made in this way. It weighed nearly 

 2,000 pounds when boxed — not an easy thing to handle — but it 

 stood shipment to New Orleans and back without suffering any 

 material injury. This would hardly have been possible had the 

 cast been made from plaster alone. 



Paper seems, at first sight, to be the material best adapted for 

 the reproduction of models ; but no one has succeeded well 

 enough with it to bring it into use. Like nearly all those who 

 have given this subject attention, I have experimented with 

 paper, but the only positive result has been a loss of a large part 

 of the confidence that I once had in the suitability of the material. 

 Paper has been used extensively for large scale models of pueblos, 

 ruins, etc., but I have never obtained a satisfactory result with 

 subjects in low relief and fine detail. A paper cast may look well 

 when first made, but it absorbs moisture from the atmosphere, 

 and contracts and expands with the weather. The contraction is 

 apt to flatten out the model and the expansion to make it buckle up. 



Casts of models have been made in iron ; but this, while suitable 



