Bill and Martha were the two children who visited the airport and who were featured in some of Mr. Pryor's other fact books. This time he has succeeded in keeping the rather patronizing tone out, and has given straight fact. In the ""glass"" book each step of the process is interestingly presented, and some simple home laboratory work suggested. The ""steel"" book takes the making of steel from the ore pits to the finished product. Many fine photographs in both volumes, though unfortunately some are obscured by dark reproduction.