The colour of sea-water as it is seen on board ship is most readily determined by comparison with the tints of Forel's xanthometer or colour scale, which consists of a series of glass tubes fixed like the rungs of a ladder in a frame and filled with a mixture of blue and yellow liquids in varying proportions.
The boards constituting the top of the bench seem long enough for side of what Molly proposed but sawing the remaining boards for rungs would prove arduous.
Neither of us was proficient at using a saw and we'd managed only two rungs when exhaustion caught up with us and the light faded for permanently.
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