The Buffet Blue Book by John H. Considine (1912, p.64)

0.5 jiggerJamaica rum base
0.5 jiggerrye whiskey base
1 lumpsugar — cut lump sugarbase
2 dashesAbbott's Bitters bitter
2 dashesorange bitters bitter
seltzer — Dissolve sugar and dash on top.dilution
  1. Dissolve the cut lump sugar in a little seltzer in an old-fashioned whiskey glass, then add the bitters, Jamaica rum, and rye whiskey.
  2. Place a small spoon in the glass, dash on top with seltzer, and serve.

See also: High Ball, Manhattan Highball

Source specifies a cut lump of sugar dissolved in a little seltzer with a small spoon placed in the glass.