524 TRANBACTIONS OF SECTION fi. 
above, there are limits to the amount of reduction which can be made 
with advantage. 
In these respects the practice of different countries varies considerably. 
In Austria the field survey is on the 3,35, scale; this is reduced to and 
drawn on the gst 5, scale, and this drawing is reproduced by heliogravure 
on the xsty7 scale. 
In France the field survey is on the zz4y5 OF syhuy scale. The 
survey is reduced to and drawn on the z54yy scale. In Algeria and Tunis, 
both field survey and drawing are on the zy4 5, scale. In all cases the 
French maps are now reproduced by heliogravure on the ;y5459 scale from 
the z,5455 scale drawings. 
In Germany the field survey is on the 351,35 scale. This is reduced 
to the z5s/509, On which scale the maps are engraved on copper. 
In Great Britain the 1-inch map is based on the 25-inch and 6-inch 
survey. These were reduced, and a fair drawing was made on the 2-inch 
scale in a manner suitable for reduction to the 1-inch scale—i.e., the detail, 
lettering, etc., were drawn so that when reduced to the 1-inch scale they 
should be in proper proportion. This drawing was reduced and printed by 
heliozincography on the 1-inch scale, and from these prints was engraved 
on copper. 
In America the field surveys are on the scales of gg455; 95450) And tyso00 
for the 53355, the qgs455, and the 35745, scale maps respectively. The 
drawings, on the same scale as the field survey, are reduced by photography 
and engraved on copper. 
I consider that the best results are obtained when the field survey is 
made on double the scale of the finished map; that if reproduction is to be 
by engraving, the fair drawing should be on the same scale as the finished 
map; that if, on the other hand, reproduction is to be by photographic 
methods, the fair drawing should be on the same scale as the survey, 
2.e., double that of the finished map. The reduction I advocate should 
conduce to accuracy of detail and, if reproduced photographically, to fine- 
ness of detail, while it is not so great that the surveyor and draughtsman 
should be unable to realise the effect of reduction. 
Detail. 
The need of considering the amount of detail, &c., to be shown is not 
always sufficiently realised. The way in.which detail is to be represented 
also needs consideration, as on small scale maps much detail has to be 
represented conventionally, 
Railways have to be shown conventionally, and should be so marked 
that they catch the eye without being too heavy. 
Roads also should be clearly marked. Where different classes of roads . 
exist they should be distinctively shown, main roads being more prominent 
than others. It is important to know what roads are fit for fast wheeled 
traffic in all weathers, and which are fit only for slow traffic. The exact 
classification of roads must depend on the conditions obtaining in the 
country. The most elaborate classification is that shown on the French 
maps, and next that shown on the maps of Great Britain. Provided that 
important distinctions are represented, the simpler the classification the 
better. 
Forests, woods, marshes, and in some cases pasture, rough pasture, 
orchards, vineyards, gardens, etc., are shown by conventional signs. While 
forests, woods, and marshes should certainly be distinguished on the maps, 
I incline to the opinion that the state of cultivation is better omitted, and 
that the less small detail shown the better. Such small detail increases 
the cost and often overcrowds the map. The German zy 4557 scale shows 
much small detail, and although the maps are beautifully and delicately 
es 
