Daly's Bartenders' Encyclopedia by Tim Daly (1903, p.31)

0.5 glassPorter base
0.5 glassold ale — Fill the balance of the glass.other
  1. Fill half a large ale glass with porter and the balance with old ale.
  2. Serve cold.

This is a useful reminder that mixed-beer service remained part of the bartender's repertoire in 1903.

Daly emphasizes temperature rather than garnish or mixing complexity.

See also: Ale Sangaree, Shandy Gaff