DRAINAGE DISTRICT ASSESSMENTS. 53 
to that class. The result is again multiplied by the percentage fixed 
for its " proximity " classification which gives what is called a ;; prod- 
uct." The " products " are all added together. The sum of the 
extraordinary benefits is subtracted from the total cost of the work, 
and the remainder is divided by the sum of the " products " which 
gives a money value for the unit " product." This unit value multi- 
plied by the number of units in each " product " gives the base assess- 
ment for each tract. The extraordinary benefit assessment, as found 
above, is then added to the base assessment to obtain the total assess- 
ment against each tract. 
Some engineers have elaborated the above system by separating 
the first two factors into their elements with still other percentage 
values, but as the foundation of this system is the value assigned to 
the various factors, these refinements do not make the system any 
more equitable and only add confusing complications. 
The first step, then, in making an assessment by this method is to 
divide the lands into classes according to their condition or need of 
drainage. To do this correctly every physical feature or condition . 
every advantage, either natural, artificial or as a matter of law. 
which affects the drainage of the tract must be considered. The field 
investigations in States using this system showed that it was the 
almost universal custom to divide the lands into four classes, known 
as " swamp," " wet," " low " and " high." 
Following this, percentages are assigned to each of the four classes 
and those used, almost without exception, are 100 for " swamp," 70 
for " wet," 30 for " low." and 5 for " high." That is, while theore- 
tically each board of assessors fixes its own values for each class, in 
practice the same values are used in many localities with widely 
different drainage conditions. The effect of this evaluation is to 
establish as a fact that " wet " land receives 70 per cent of the bene- 
fit received by " swamp " land, and that " low " land receives 30 per 
cent and " high " land 5 per cent of that benefit. This is an arbi- 
trary assumption and is without foundation in fact. It is possible 
that, at some particular time and for some particular lands, this pro- 
portion was correct, but it obviously can not be true for all drainage 
districts at all times. The conditions surrounding each tract in most 
districts vary so greatly that it is impossible to prove that where an 
acre of " swamp " land receives a benefit from drainage of $100. an 
acre of " wet " land will always receive a benefit of $70 solely be- 
cause it is classified as " wet " land. In fact, almost every drainage 
engineer can recall drainage districts in which the proper relation 
between the resulting benefits would be more correctly expressed by 
reversing this ratio. 
Again, there must necessarily be a wide variation in the nature of 
the land classified as " swamp," " wet," and " low," in various dis- 
tricts. In each district the wettest land will naturally be placed in 
the " swamp " class, with the next wettest in the " wet " class. In one 
district the " swamp " land may be land which is always under water 
while in others it may be land which is overflowed at interval- or 
land which is dry enough to produce good crops of hay. How can 
it be established that the relative benefits between these various 
degrees of ; " swamp " land and the various lands called ,; wet." " low," 
and " high " will always be 100, 70, 30. and 5 1 It is clear that 
