<div class="htmlview paragraph"><b>C</b>YLINDER-BLOCKS, with their hollow form and complicated arrangement of water-jackets, valve passages, pockets and bearings, are difficult to cast, and require a large quantity of cores. These have generally been baked or dry-sand cores, but the author's organization has met with success in making the more bulky cores, those for the cylinder-barrels and crankcase, in green sand. Descriptions and copious photographs and drawings are given of two methods of molding one six-cylinder block in green sand, and the possibilities of the system are indicated by illustrations of cylinders and details of cylinders that have been molded or that are suitable for molding in green sand.</div> <div class="htmlview paragraph">Cooperation between designer and foundryman is essential in realizing the economy possible with this method of molding, a large part of which results from the great saving in cost of sand. Core-room and foundry layouts are given, also a comparative analysis of the cost of cores, made as far as practicable by the green-sand method, with the cost of dry-sand cores.</div>