When an Army engineer prophesied last fall (TIME, Oct. 26) that some fine day the shattering clangor of pneumatic rivet-hammers would no longer be heard upon the metallic skeletons of city buildings, ...

Let's start by defining the term planishing, which means to smooth by light hammering. Metalworkers have been planishing sheetmetal parts ever since hammers were invented. The basic idea is that ...