some as many as twenty. There is, however, a way of circumventing some of these difficulties. In each state supplement the total value of each kind of crop (except where different things are lumped together as above indicated) is given, and by dividing this by the number of acres, bales, pounds, or bushels we can get the average value per unit for that state, which we may assume without serious error to be the same for every subdivision of the state. This gives us a means of reducing the county crop statistics to a common unit. Although value varies considerably at different times and places, it is a better criterion for comparison than acreage, for an acre of strawberries or lettuce, for instance, is worth far more than an acre of corn or wheat, because it requires so much more labor for planting, harvesting, etc.

Some of the states gather agricultural statistics of their own which are more complete than the Government statistics, but this does not happen to be the case with Georgia, the one selected for illustration. The crop statistics published biennially by the Florida Agricultural Department give the value of every important crop (separating all the different vegetables) in every county, and these were used by the writer a few years ago in determining the principal crops in all parts of northern Florida.

In putting these features on maps one map should be used for each kind, and the names of as many things as there is room for printed right in the proper spaces, in order to abundance, or area, or value, as the case may be. The differences between any two neighboring regions in that particular are then very evident. Abbreviations or symbols can be used to save space when necessary, and regions too small to put anything in can either be left blank (being of little importance with reference to the whole area mapped), or else their features can be printed out in the margin somewhere and connected with the proper region by a guiding line. As a region which extends through several states but is commonly regarded as a unit (like the Piedmont region and the Appalachian valley) may vary somewhat in different parts, on account of gradations of elevation, climate, or something else, it is well to work out the statistics for each state separately and map them accordingly, to show just what the variations are. Of course the method here described is just as applicable to political divisions as to natural geographi

'See 6th Ann. Rep. Fla. Geol. Surv., pp. 188-189, etc. 1914.

cal divisions, but to use political divisions alone would be unscientific, and would sacrifice the fundamental principle of maximum contrast to expediency. However, where we are not sure of the natural boundaries we may take certain crops of counties for trial, and after computing statistics for them find that shifting a certain county from one region to another gives more contrast, and thus gradually make our regions more nearly natural.

If we had county statistics of manufacturers they could be mapped in the same way as crops, but unfortunately the Government publishes manufacturing statistics only for states and

principal cities. Climate and population do not lend themselves well to this sort of treatment, but their salient features for each region might be put on the map in a few words. Topography could be treated statistically, if one wanted to take the trouble to do it, by estimating the area lying between 0 and 100 feet altitude, 100 and 200, etc.; and this was actually done for the whole United States in the tenth census, and correlated with population, etc.

The principles here discussed will now be illustrated by four maps of Georgia. The first shows the names of the twelve subdivisions, the second the soils, the third trees, and the fourth crops. The four northernmost divisions belong to the highlands, and the remainder to the coastal plain. Their boundaries

Clay loam
Sandy loam
Coarse sandy loam
Clay
Meadow

Sandy loam Sand, Coarse sand

Sandy loam, Coarse sandy

Sandy loam, Fine sandy loam, Sand, Loamy sand, Clay loam

Clay

Fine sandy loan

Sand

SANDY LOAM/
Sand

Clay loam

Swamp
Meadow

FINE SANDY LOAM
Meadow, Fine sand

SANDY LOAM
Sand

Fine sandy loam
Swamp

Marsh Fine sand Clay Swamp

Fine sandy loam

are based largely but not entirely on geological formations. On the last three maps the aim has been to list everything that makes up as much as five per cent of the total. Approximate percentages could have been given in every case, but the fundamental data are not yet accurate enough to justify the undertaking. (Perhaps they will be after the next decennial census.) But to give some idea of abundance, wherever an item at the head of a list is believed to constitute over half the total, its name is printed in capitals. (If one had the necessary skill and patience each name could be written in a size proportionate to the abundance of the thing named.) It is useful to bear in mind that the percentages of abundance tend to form a geometrical progression, like the populations of the cities of the United States, arranged in order of size.

The soil data have been taken from the Government soil surveys published up to the end of 1916, of which there are about forty-two for Georgia. The information about vegetation is based wholly on personal exploration, and covers only the trees, which are the most conspicuous and important part of the vegetation. Technical names are used because they are more definite, the same common name often being applied by the natives in different regions to two or more distinct species of trees. For the benefit of nonbotanical readers a glossary of the names used is appended here. Where only one species of a genus appears on the map the specific name is omitted to save space.