Addressing Machine

By hand, write one address ten times. Time it. This is the cost Duncan attacked.

The patent specifies rubber type set into the links of an endless chain, not embossed metal plates. Note the difference now — you will meet the myth in step 14.

Cut eight cardboard rectangles 60 × 30 mm. Each is one link and will carry one address.

Cut a shallow window in each link to hold type by compression. The recess must grip without glue — that is Duncan's claim.

Press rubber letters into the recesses of three links to spell three short, different addresses. They should hold by friction alone.

Turn each link upside down and shake. If type falls out, the recess is too loose. Adjust until it holds.

Punch and wire the links together into a closed loop. It must flex at every joint.

Mount a dowel horizontally on the board so the chain hangs over it and can be advanced link by link.

Roll ink onto whichever link sits at the bottom of the drum.

Press paper against the inked link. Lift straight up — no sliding.

Move the chain one link and print again. Two different addresses, one machine, no rewriting.

Print all three addresses in rotation, ten sheets total. Time it and compare with step 1.

Advance two links without printing. Duncan's machine let an operator select which addresses to print — the beginning of the mailing list as a data structure.

US 558,936, “Addressing-Machine”, Joseph S. Duncan, granted 28 April 1896, filed 2 August 1893.

🔴 The embossed-plate story is wrong for this patent. Reference works routinely describe US 558,936 as a mechanical imprinter using embossed metal plates with a reciprocating platen. The document says otherwise: rubber type, compressed into recesses in metal link-plates forming an endless chain over a drum, in the inventor's own words. Embossed metal plates belong to the later Addressograph and to the Graphotype machine that embossed them. The description has been back-projected from the famous later product onto the founding patent.

Duncan developed the idea from 1892 work; the “Baby O” model went into production on 26 July 1893 in a back room of the old Caxton Building in Chicago, and he formed the Addressograph International Company in 1896.

Why it belongs beside the tabulator and the cash register. All three are machines that hold business information in physical form and act on it selectively — Hollerith's punched strips, Ritty's registered transactions, Duncan's addressed links. The mailing list, the audit trail and the census are the same idea in three costumes, and they are the direct ancestors of the database.

Addressograph plates outlived the machines: the same principle survived into the metal credit-card imprinters that were still clattering on shop counters in the 1980s.