Iviii INTRODUCTION. 



Table 92. Quantity of water corresponding to given depths of rainfall. 



This table gives for different depths of rainfall ov^er an acre and a 

 square mile the total quantity of water measured in imperial gallons and 

 tons respectively. 



Table 93. Dates of Dove' s peyitades. 



For tabulating and averaging meteorological data, Dove divided the 

 year into seventy-three intervals of five days each, which have been called, 

 Dove's pentades, and this system of averaging has been used in the 

 publication of a very considerable amount of meteorological data. Table 

 93 gives the initial and terminal dates of each pentade throughout the year. 



Table 94. Division by 2'^ of minibers from 28 to 867972. 

 Table 95. Division by 29 of numbers from 29 to 898971. 

 Table 96. Divisio?i by ^^y of numbers from -^x to 960969. 



The frequent occasion in meteorological work to divide by the numbers 

 28, 29 and 31 renders useful the division tables compiled by Mr. H. A. 

 Hazen (Handbook of Meteorological Tables, Washington, D. C, 1888), the 

 use of which has been kindly granted. 



As here printed, the dividend is given in plain type and the quotient in 

 heav5''-face type, and in order that one shall never be mistaken for the other, a 

 column is given containing the letters D and Q successively, which 

 designates that all figures on a line with D are dividends, and all on 

 a line with Q are quotients. The four columns to the right of this D-Q 

 column give the last two figures of the dividend and of the quotient, 

 namely, the units and tens. The ten columns to the left side of the 

 D-Q column give the preceeding figures of the dividend, namely, the 

 hundreds, thousands, and tens of thousands. These two parts of the 

 dividend — to the left and right of the D-Q column — are always to be taken 

 on the same horizontal line. 



Each dividend is an exact multiple of the divisor, hence each quotient 

 is exact or without remainder. 



For example, the dividend 17360 in Table 94 is found in two parts ; 

 173 is found in the column headed 600 on the left-hand side of the D-Q 

 column, and 60 in the same horizontal row in the third column on the right- 

 hand side. 



The hundreds figure of the quotient is given in bold-face type at the 

 top, middle and bottom of the page, and each one obtains for all the dividend 

 figures in its own column. The units and tens figures of the quotient are 

 found, as alreadj' stated, on the right side of the D-Q column directly under 

 the last two figures of the dividend. Thus in the above example, for dividend 

 17360 the hundreds figure of the quotient is 6 and the units and tens will be 

 20, or the quotient of 17360 divided by 28 is 620. When any given dividend 



