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.
The dowel plate is a steel plate about 1/2 in. thick, with holes from 3/16 in. to 1/2 in., and centre-bits are fitted and marked so that dowel pins made in the holes will fit holes made by the corresponding bits.