This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
This handy little device enables any mechanic instantaneously to centre any round, square, oval, triangular, hexagonal, or octagonal article for the purpose of drilling or turning. In use the punch is held upright (as shown in Fig. 269) over the article to be centred, and the punch centre tapped, when the true centre of any geometrically-shaped article will be found. It will centre any size from 1/4 to 1 in. diam., and costs from 3s. upwards.