LOGARITHMS. \\i\ 



f being added, as to add a column in which all are positive. 



And if the negative chara . ined, all care and writing of 10 or 



its multiples is avoided. Moreover, tin- logarithm is complete in itself and 



!..g of a decimal fraction. The>- remarks apply not 



only to the logarithms of ordinary numbers but t.> the logarithm* of the trigono- 



Example of addition where some of the characteristics an negative. Places 

 1 the first of the mantissa are not added in this illustration. 



2.4036 Inning at the bottom of the columns we have 



T.2I68 5 + 3 = 8 -f 2 = 10 + 4 = 14, write 4 ; 



^3462 carry 1 + 2 = 1+ i = + 7 = 1 + 2 = 1. 



use the tiguivs printed in heavy type are the only ones pro- 



1.4 nounced or mentally enforced. 



Examples of some cases where the use of the notation by powers of 10 



enable one to dispense with the characteristic in portions of computations are 

 ily at page xxi. 



Grouping by Fives in the Tables. Throughout the entire set 

 of tables, it will be observed, the columns and lines aiv arranged in 

 groups of five. Thjs not only aids the eye to readily follow any 

 I line or column, but enables the computer with a little prac- 

 tice to enter a desired column or line without glancing at the num- 

 ber at the top of the column or side <>f the line, and similarly l< 



6 number of column or line without glancing off to the marginal 

 Thus the middle column in the second group is 7. the last 

 in the lirst group is 4. ami so on. The praetiee ( .f working by 

 position rather than by the marginal number should IM> 

 ie.l. It reduces fatigue and tends to prevent mistal, 

 Indexing at Corners of Tables. The bold type at the out.: 

 ners of the tables shows the contents of the page and ii 

 Thus on the sixth page of the tive-plaee log table, the larger black 

 figure 2 shows that these two priors contain the logs of all the num- 

 bers beginning with '2. The smaller Marl, 30, 47, in the 

 :iat the mantissa- on the two pages extern! from 30 to 

 i. The indexing will lie found a material help 

 idly running the page under the finger to find either a 

 .iblc or a i'le. 



Decimal Point in Logarithm Tables. It is the almost universal 



i to omit the decimal point entirely from logarithm tables. 



This tends to,\ard eompaetuess. hut is ! lalonthat 



I . onvenienoe after slight 



