PREFACE. 



>, ould probably be within safe limits to assert that one-half of 

 me expended in computations is wasted through tin* use of an 

 lumber of places of figures, ami through failure to employ 

 >'his waste rni.^ht bo almost wholly avoided by follow- 

 ing a few simple computation rules and practi -;'htly with 

 ithm tab'. 



:u tlie use of supei-Huous figures will b 



when it is considered that in director logarithmic multiplication and 

 division with four. tivo. and six places of 1 inures the work is r 



in the ratio of i : 2 : 3, or perhaps more nearly 1:3:4. Thus 

 (Diiti. fallacious excuse so commonly .uiven that it is just 



to use six- or seven-place tables as smaller on. 



work is doubl' led by the use ..f six pla> ,d of fmir. 



tlie employment 01 seven-place tables, and dropping 



limns places when four o; desired. much loss 



mployment of logarithm- k of four or more 



and upward of the time 



required t multiplication or division, with 



11 id a u r ain 



in simjilo rules to enable 



for himself tic :i. how many ila - "iiu'ht 1 t<> use 



in this eomput. tlie nota- 



. more 01 el in 



is to the me of the logarithm and other tabh-s: and a Coll 



! 'ilh-ction .Iain all the niathe- 



. 



;dents 



l'(M 



