568 Journal of Agriculture . Victoria. [ic Aug., 191 i. 



Material for an All-Sfeel Silo. 

 The material required, in addition to the wall sections supplied by the 

 patentee, and stumps, which can be provided by farmer, is as follows : — 



Hardwood, 4-in. x 2-i)i. ; 2 20-ft., 4 i6-ft., purlins. 



Hardwood, 3-in. x i^-in. ; 2 12-ft., 2 20-ft., uprights for ladders. 



Hardwood, 3-in x i-in. ; 2 20-ft., treads for ladders. 



Oregon, g-in. x 2-in. ; i i6-ft., scatfold. 



Stanchions, 2 3-ft., 4 2-ft. 



Galvanized iron corrugated sheets, 26 gauge; 16 Q-ft., roof. 



Galvanized iron ridging, 26 gauge; 3 lengths i6-in. 



Galvanized iron spring-head nails, 3 lbs. 2^-in. 



Bolts, nuts, and washers, 2 5-in. x |-in. 



Bolts, nuts, and washers, 4 45-in. x g-in. 



Bolts, nuts, and washers, 4 3-in. x |-in. 



Wire nails, 3 lbs. 2-in. 



CONCRETE SILO. 



The popularity of concrete is steadily increasing for the construction of 

 all classes of buildings. When one considers that it is fire, wh-ite ant. 

 and vermin proof, and added to that the virtue of being cheaper than any 

 other material, and more durable, its u.se should be fully ju.stified. 

 There is very little difficulty in making good concrete if care be taken 

 in the following advice here given. 



Concrete is composed of metal (broken stone) or gravel mixed with 

 .sand and Portland cement in certain proportions and wetted. In " fine" 

 concrete, no metal is used, small gravel taking its place. Cement and sand 

 alone form a mortar or " compo. " The proportions of the various mate- 

 rials depend upon the air voids or spaces in the metal or gravel, and upon 

 the strength of concrete required, varying with the uses to which it is to 

 be put, engine foundations and hollow blocks representing the strong 

 .side, and building foundations and solid walls the weaker class. The 

 mortar or compo of sand and cement should be sufficient in bulk to fill 

 all the voids in the metal, ])referably somewhat in excess, say about 10 

 per '^ent. 



The voids can be found by filling a kero-sene tin with the metal or 

 gravel, making a bulk of 4 gallons ; the whole is then weighed, allowance 

 being made for weight of tin. Water is poured in until flush with the 

 surface and the tin with its contents is again weighed. Thus, as water 

 weighs 10 lbs. to the gallon, the percentage is arrived at. For instance, a 

 kerosene tin of metal weighed 60 lbs. deducting the w^eight of the tin. 

 When filled with water, it weighed 78 lbs. Consequently, the void space 

 was represented by 18 lbs. of water, while the whole volume. 4 gallons, 

 weighed 40 lbs. Thus, the percentage of void was found to be 45. A 

 good mixture in this instance would be 6 parts of metal, 2 parts of sand, 

 and r part of cement. 



In the example given, the metal was fairlv large — about 2| in. The 

 percentage of void space increases as the size of metal or gravel diminishes, 

 running from 35 to 45 in ordinary cases. For fine work, such as hollow 

 blocks, fine gravel, if not greater than l-\n. diameter, is used. If it is 

 mixed with sand, so much the better. In such a case, cement should 

 be added in a proportion ascertained in a similar way to that already 

 described, and should be not less than one-sixth of the bulk, and about 

 one-half of the sand contents. 



Before, however, working out the proportions, the material should be 

 selected, care being taken that the metal or gravel is of fairlv strong and 

 clean stone; soft sandstones or limestones are to be avoided. The sand, 

 in particular, should be sharp and washed clean — it should lose but little 



