189. The question of choosing the best floor system out of the many of nearly equal merit, hinges largely on the cost, as any of those that have been described will be found amply strong and thoroughly fireproof, if constructed properly. Although, perhaps, the greater number of architects prefer the use of arch tile floors, the combinations of concrete and steel and iron are much used; such floors have passed through the experimental stage, and have shown that they make a very strong and thoroughly fireproof construction. Other things being equal, the floor that is lightest is the best, as the weight and size of beams, girders, columns, etc. may then be considerably lessened, which is an important factor in the cost of the structure. Where strength is the object sought, those floors should be used which have shown sufficient strength to meet the requirements of the case. In all floors, the character of the workmanship, and the quality of the materials used, have a great deal to do with the durability and efficiency, and hence should receive careful attention during construction.