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both methods are in use at the present time. The best 

 rules governing former practice are given below. 



Fuller's Rule: An approximate rule for ready calcula- 

 tion is the one originated by Mr. Wm. B. Fuller, and is as 

 follows: Divide 11 by the sum of the parts (by volume) 

 of all the ingredients; the quotient is the number of bar- 

 rels of Portland cement required per cu. yd. of concrete. 

 Multiplying this by the number of parts of sand and of 

 stone will give the number of barrels of each. To reduce 

 barrels to cu. yd., multiply by 0.14 (since a barrel con- 

 tains 3.8 cu. ft. and there are 27 cu. ft. in a cu. yd.) 



On proportioning concrete for maximum density, Mr. 

 Fuller says: 



Procure a piece of steel pipe 8 to 12 in. in diameter and 

 a foot long and close off one end; also obtain an accurate 

 weighing scale. Weigh out any proportions selected at 

 random, of cement, sand and stone, and of such quantity 

 as will fill the pipe about three-quarters full, and mix 

 thoroughly with water on an impervious platform, such 

 as a sheet of iron; then, standing the pipe on end, put 

 all the concrete in the pipe, tamping it thoroughly, and 

 where all is in, measure and record the depth of the con- 

 crete in the pipe. Now throw this concrete away, clean 

 the pipe and tools and make up another batch with the 

 total weight of cement, sand and stone the same as before 

 but with the proportions of the sand to the stone slightly 

 different. Mix and place as before and measure and 

 record the depth in the pipe, and if the depth in the pipe 

 is less and the concrete still looks nice and works well, this 

 is a better mixture than the first. Continue trying in this 

 way until the proportion has been found which will give 

 the least depth in the pipe. This simply shows that the 

 same amount of materials is being compacted into a 

 smaller space and that consequently the concrete is more 

 dense. Of course, exactly similar material must be used 

 as are to be used on the work, and after having in this 

 way decided on the proportions to be used on the work 

 it is desirable to make such trials several times while the 

 work is in progress, to be sure there is no great change 

 in materials, or, if there is any change, to determine the 

 corresponding change in the proportions. 



The above described method of obtaining proportions 

 does not take very much time, is not difficult, and a little 

 trouble taken in this way will often be productive of very 

 important results over the guess method of deciding pro- 

 portions so universally prevalent. 



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