Piers note: No. 91. York Redoubt: Caponier (of ironstone, loopholed) which flanks or enfilades the ditch of east front; with ironstone Escarp and Parapets, and Embrasures for Numbers 7 and 8, 9-inch R.M.L. Guns; the loopholed parapet of Duke of York's Tower is seen over Number 7 Guns, and to right is parapet over the Casemate (No. 92). In foreground is a cable trolley used for transporting construction materials. 1873. Looking Northwest from without the work and to east of hoisting engine. Same view as later one, No. 288.
Reference: Royal Engineers Nova Scotia Archives number 6988 (Piers 91) / negative N-2032
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