Scale 1:24. Plan shows the midship section of the Twin Screw Submarine Design No. 668 (not built). A Vickers Limited stamp dated 20 January 1914 is present on the drawing. The drawing also bears the signature of the Chief Constructor at Vickers Ltd. The title of the plan is "Structural Sections for a Twin Screw Submersible Vessel". The words "Vickers Double Hulled 'E' Submarine Sections" are written on the reverse.