it, irrigation, or reclamation of swamp areas—are made with 
sed in the publication 
e ° ' wiw 1 inch=one-half mile), with a contour interval of 
$1,6-30 
, or 10 feet [ i|l-il f r fl: H t is*} i3j-j 
. Surveys of areas in which there are problems of average 
lie importance, such as most of the basin of the Mississippi 
its tributaries, are made with sufficient accuracy to be used 
he publication of maps on alscale of ~~ (1 inch=nearly 
HHwith a contour interval of 10 to 25 feet -A.. 
rveys of areas in which the problems are of minor 
lie importance, such as much of the mountain or desert 
on Arize Mexico, are made with si 
in the publication | of maps on a scale of 
(1 inch — nearly 2 miles), with a contour interval of 25 to 
topographic survey of Alaska has been in progress since 
8, and nearly 43 per cent of its area has now been mapped, 
but 10 per cent of the Territory has been covered by recon- 
Bsanee maps on a scale of > or about 10 miles to an 
jpMost oi the remaining area surveyed m Alaska has 
i mapped on a scale of but about 4,000 square miles 
tapped on 
Ibe Hawaiian Islands, with the exception of the small 
|nds at the western end of the group, have been surveyed, 
the resulting maps are published ou a scale of — 
he features shown on these maps may be arranged in three 
jps—(1) water, including seas, lakes, rivers, canals, swamps, 
other bodies of water; (2) relief, including mountains, 
|s, valleys, and other features of the land surface; (3) culture 
I 
