Page 15 Advertisements Column 1

Evening Post, Volume CIV, Issue 7, 8 July 1922, Page 15

Ono school in Carnarvonshire has only seven pupils, while five have fewer than fourteen each. Charles Dickens insisted upon having his bed placed north and south, and it is said that he carried a.compass in his luggage to ensure the correct degreo. Concrete is being used in increasing quantities for. building construction in the Dominion, for business or residential premises, bridges, walls, and stays. In such a country as New Zealand, subject as it is to earthquakes, it is essential that the very best of materials shall be used in the making of concrete, for one weak spot will endanger the whole construction. Silt, mud, or similar substances, if used in concrete materials, must have a deleterious effect upon the strength of the finished article, for such rubbish has nob the sharpness of substance upon which the cement can obtain grip, and will not give that degree of solidity and hardness which is essential for safety. First-class 'concrete requires sand of sharp, hard, and gritty grains not less than one sixty-fourth of an inch in size, and not more than 10 per cent, should pass through a sieve of this mesh. As a result of scientific tests, Hutt River unwashed shingle gives a breaking strength of 22401b per square inch, while Hutt River Shingle Company's stone, crushed, washed, and graded, and washed sand; give a breaking strength of SipOOlb per square inch. The reason is due to the use of crushed stone and clean material, which give an increased breaking strength of 25 per cent. Broken stone, having a rough surface, is of far' greater value for strength in concrete than smooth stone, for it is the roughness and grittincss _ that allow the cement to grip, and reduces the risk of fracture to a minimum. Regard of course, mus'u bo paid to quantities but quality is of first importance. This is a. matter of considerable interest to architects and builders, 'to whom results of further tests will be supplied by Hutt River Company. See announcement on peas four of thie i**ue,—-Advt,