ADDENDA. 475 



Fat from total solids and specific gravity. Place the cursor 

 against the figure on the total solids scale, adjust the figure 

 on the specific gravity scale to this, and the fat is read off on 

 the fat scale on the slide by means of the arrow in the left- 

 hand corner. (Note. This scale reads from left to right.) 



Total solids from fat and specific gravity. Place the figure 

 on the fat scale against the arrow in the left-hand corner, 

 and the total solids can be read off against the specific gravity. 



Solids not fat from fat and specific gravity. Place the arrow 

 on the slide against the fat for SnF scale (left-hand corner of 

 rule), and the solids not fat can be read off against the specific 

 gravity. 



P. 361. Added water from solids not fat. Adjust the cursor to the figure 

 on the solids not fat scale, and the percentage of added water 

 is read off directly. 



Added water from G -f F. Adjust the cursor to on the 

 added water scale, then bring 34-5 on the specific gravity scale 

 to the line, and adjust the cursor to the'value of G + F on the 

 specific gravity scale, and the percentage of added water is 

 read off directly. (Note. There is a very slight error, the value 

 being 7 V too high.) 



P. 362. Fat abstracted from fat. Find the fat on the scale on the slide, 

 and the percentage of fat abstracted can be read off directly 

 at the corresponding point on the fat abstracted scale. 



Multiplication. By the use of the scales on the lower part 

 of the slide numbers can be multiplied. Find one number on 

 the lower scale, adjust either 1 or 10 upper scale against this, 

 place the cursor against the other number on the upper scale 

 and the product is read directly from the lower scale. If 

 necessary, the numbers must be multiplied by 10, 100, 1,000, 

 or rV TW> e ^ c -j * bring them to the scales, and it must be 

 remembered that, if 10 is placed against the number, the figures 

 for the product read on the lower scale are multiplied by 10. 



Thus, if we multiply 22 by 17, we have to take T V of each 

 of these to get them on the scales, and the product must, 

 therefore, be multiplied by 100. 



Thus, 17 = 1-7 x 10 



22 = 2-2 x 10 

 1-7X 2-2 = 3-74 

 which has to be multiplied by 



100 = 374 

 or 45 x 0-36 



45 = 4-5 X 10 

 0-36 = 3-6^- 10 



4-5 x 3-6 = 1-62 (from scale) multiplied by 10, because 

 10 was placed against 4-5. The answer, therefore, is 16-2 

 X 10 4- 10 = 16-2. 



The placing of the decimal point (or unit place) soon becomes 

 almost automatic, but if there is any doubt the above rules 

 will give the correct answer. 



The slide rule only gives 3 significant figures, and if, say, 

 537 is multiplied by 184, the slide rule will only give 9-88 

 X 100 X 100 instead of 98808, but it is rarely that accuracy 

 greater than three figures is essential. 



