86 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
exaggeration, these have a greater or less value. Good models of 
this class are certainly extremely useful. On an intermediate scale, 
areas as great as the United States are attempted; hut with this 
decrease of scale, there is nearly always an increase of vertical 
exaggeration. Yet Howell’s models of the United States on a 
curved surface are certainly very instructive. Even entire conti¬ 
nents, such as those made for Butler’s Geography by Mindeleff, 
have much value when delicately treated; but their very delicacy 
makes them so crowded with detail that their use in elementary 
teaching; is lessened. But when the scale is so small that the model 
embraces the whole earth, the necessary exaggeration of the ver¬ 
tical element is so great as to make them of questionable value. 
They forcibly impress so much that is erroneous, in the matter of 
proportional dimensions, that it is doubtful whether they do not 
teach more error than truth. 
Large scale reliefs, in the neighborhood of an inch to a mile, may 
exhibit much detail of form, sufficient to give real physiographic 
expression. Exaggeration may here be very small, or even zero. 
Some of the finest models of this class include the more popularly 
visited parts of the Alps, and are to be seen in various European 
museums. They are elaborately wrought, with much artistic effect 
in form and color. Their cost is forbidding. The most accurate 
models of this kind known to me are those constructed by the 
Geographical Service of the French Army, for military purposes. 
One of this series, exhibited at the World’s Fair, and afterwards 
presented to the Geographical Laboratory of Harvard University, is 
on a scale of 1 :20,000, horizontal and vertical. The relief is 
mechanically constructed with remarkable accuracy according to 
detailed surveys; and the colored contoured maps, cut into small 
rectangles, are then most skilfully pasted on the relief without 
tearing, and so nicely that every contour line falls into a horizontal 
plane. These models are not “ on the market.” D. Locclii of 
Turin has recently made an excellent model of the terminal 
moraines south of Lake Garda for the Italian Military School, 
copies of which are for sale, price about 300 lire (160.00). 
Few models of large scale have been made in this country. 
Among the best are those by Harden, prepared some years ago for 
the Second Geological Survey of Pennsylvania, and those of certain 
Appalachian districts, prepared by Howell. A photographic repro¬ 
duction of an example of the latter may be seen in the National 
