Under these favorable conditions, the appearance presented was not unlike that of the liquid in a vast natural dyeing-vat.
A clouded state of the sky, as was to be expected, produced the well-known effects due to the diminished intensity of light; the shades of blue became darker, and, in extreme cases, almost black-blue.

According to our observations, the obscurations of the sky by the interposition of clouds produced no other modifications of tints than those due to a diminution of luminosity.
In places where the depth is comparatively small and the bottom is visibly white, the water assumes various shades of green; from a delicate apple-green to the most exquisite emerald-green.

Near the southern and western shores of the Lake, the white, sandy bottom brings out the green tints very strikingly.

In the charming _cul-de-sac_ called "Emerald Bay," it is remarkably conspicuous and exquisitely beautiful.
In places where the stratum of water covering white portions of the bottom is only a few meters in thickness, the green hue is not perceptible, unless viewed from such a distance that the rays of light emitted obliquely from the white surface have traversed a considerable thickness of the liquid before reaching the eye of the observer.
The experiments with the submerged white dinner-plate, in testing the transparency of the water, incidentally manifested, to some extent, the influence of depth on the color of the water.

The white disk presented a bluish-green tint at the depth of from nine to twelve meters; at about fifteen meters it assumed a greenish-blue hue, and the blue element increased in distinctness with augmenting depth, until the disk became invisible or undistinguishable in the surrounding mass of blue waters.