476 ADDENDA. 



Division may be performed by finding the number to be 

 divided on the bottom scale, and placing the divisor on the 

 scale on the slide against it ; the answer is read off on the 

 lower scale either against 1 or 10 in the latter case, the value 

 being divided by 10, thus 



286 + 54 



286 = 2-86 X 100 

 54 = 5-4 X 10 

 2-86 -f- 5-4 = 5-3 4- 10 

 Answer, 0-53 x 100 -=- 10 - 5-3. 



1-210-h 6-4 



1-21 x 1 = 1-21 

 0-64 + 10 = 6-4 



1-21 ^ 6-4 = 1-89 -:- 10 (as it is against 10) 

 Answer, 1-89 x 10 x 1 -=- 10 = 1-89 instead of 1-8906. 



To Solve a, Fraction. It will often save time if a figure in the 

 denominator is placed against a figure in the numerator and 

 the answer read off against a second figure in the numerator. 



6-64 x 1-43 

 Example, ^ . 



Place 2-47 on the slide against 6-64 on the scale, and the 

 answer (3-84) is on the rule against 1-43 on the slide. 



p. 433. Milk Churning. To find the number of pounds of butter to be 



obtained from a quantity of milk of a given percentage of fat 

 expressed in gallons, place the cursor against the percentage 

 of fat on the milk churning scale, place 1 or 10 on the slide 

 against this, move the cursor to the gallons on the scale on the 

 slide, and the pounds of butter will be found on the lower scale, 

 this figure being divided by 10. Ex. 41 gallons of milk of 

 3-7 per cent, fat, 41 = 4-1 X 10. 10 on scale against 3-7. 

 Pounds indicated = 1-72 x 10. 



Answer, 1-72 x 10 -=- 10 x 10 = 17-2 pounds. 



If the quantity of milk be expressed in pounds, divide by 

 1 -032 instead of 10 ; this is done by placing 1 -032 against the 

 answer in the preceding operation and reading off the new 

 answer. 



Cream Churning. To find the number of pounds of butter 

 to be obtained from a quantity of cream of a given percentage 

 of fat expressed in quarts, place the cursor against the per- 

 centage of fat on the cream churning scale, place 1 or 10 on the 

 slide against this and proceed as for milk. The figure obtained 

 is read direct, and does not require to be multiplied by 10. 



If the quantity of cream be expressed in pounds, divide by 

 the weight of a quart of cream, which is obtained from the 

 weight of cream scale in the left-hand bottom corner ; find the 

 percentage of fat on the lower position, and pounds per quart 

 corresponds with this on the upper portion. Note that the scales 

 go different ways. 



P. 250. To find the value of 0-262 P' 63 + 0-09 (required in the estima- 

 tion of the percentage of butter in margarine) corresponding 

 with a given Polenske figure, find the Polenske figure in the top 

 left-hand corner, and the value required will correspond with 

 this. 



