Given the letter date, apparently the latter half of 1898, and given that the farthest overseas the unit reached is Hawaii, there are really only 3 uniform probabilities the letter writer is describing, all US Army regulation and available by latter 1898 in large numbers due to war time contracts. The 'light flannels' term is vague, but may refer to the standard blue wool fatique uniform with - possibly - the unlined 5 button sack coat. The brown canvas is the 1884 pattern fatigue coat & trousers which wound up being used by so many units at the time. And as for the 'duck' uniform, I am certain this was the 1888 white cotton duck 5 button sack coat and trousers issued in the pacific theater at the time. All 3 of these uniforms tended to show up in one combination or another in pacific theater soldier groupings, and are readily seen in photos. Despite the advent of a regulation khaki fatigue uniform, tthese took a while to show up and generally don't start to appear until later in 1899. For soldiers in the Philippines the first khakis received were the British pattern obtained from Hong Kong, however, I never uncovered any evidence (that I recall) showing these sent farther east, to Hawaii, for issue to garrison units stationed outside the war zone.
Edited by CAC1901, 15 December 2019 - 04:18 PM.