16 FORMS OF METER RATES NOW IN USE 



Schedules with three rates give more flexibility, especially 

 where the amount of slide is considerable. The three-rate 

 schedule was adopted by a Committee on Water Rates of the 

 New England Water Works Association and the points of slide 

 were defined. The form of schedule recommended by this 

 Committee will be found in Chapter V. 



Scales with four or more points of slide have been commonly 

 used and in some cases the number of rates has been very great. 

 If the changes in the sliding scale are made very numerous, the 

 irregularities can be practically smoothed out and the scale of 

 rates become almost a table showing the amount to be collected 

 for each quantity of water that is drawn. 



It may be pointed out that with a schedule of this kind, the 

 number of divisions can be made so great that it is immaterial 

 whether the jump scale or the common sliding scale is used. 

 Either scale can be arranged to produce substantially the same 

 results, or, in other words, to produce the same charges for the 

 same quantities of water. It is only necessary that the changes 

 should be sufficiently great to make this possible. 



Logarithmic Rate Scale. Mr. J. H. Harlow states (in con- 

 versation with the author) that he used a logarithmic scale of 

 water rates in some small companies with which he was connected 

 some twenty years ago. 



The amount to be paid for water can be described by a loga- 

 rithmic equation. If Q is the number of thousands of gallons 

 drawn per annum, C is a constant and x is an exponent. The 

 amount of the bill (B) may be found as follows: 



The amount of slide that it is desired to produce depends upon 

 the value of the exponent. For the uniform water rate x = i. 

 For a sliding scale, giving manufacturers a lower rate than the 

 smaller consumers, x would be less than i. 



Mr. Harlow states that he practically used x =0.9 to give an 

 amount o* slide that corresponded approximately on an average 

 with the slide that was used in the systems with which he com- 

 pared rates before adopting it. Studies based on representative 



