Shake with ice, pour unstrained, top with seltzer.
Not a recreation, but an update, of the rum ration given out to enlisted men in the British navy ca. 1867, as outlined in Zach Pearson's recent article on the Gimlet. The rum's volume has been bumped up to approximate the proof of navy rum, and the water cut down and partially replaced with ice. Lime cordial can be used in place of the juice and syrup.