which is before him. The flash of color to the normal-eyed is instantaneous, and hence the value of color for signals, and safety in having only normal-eyed in positions where so much depends on their being felt "like a slap in the face," as my friend, Prof. Camalt, said in arguing before the Massachusetts Railroad Legislature Committee.
As to Redard's wholly theoretical suggestion of the use of bluish-green as opposed to red, experience has shown that it is precisely the bluish-green glass which must be discarded, because all the blue in it breaks down the light to such an extent that, in consequence, two distinct starboard lights are sold on the ships. One of them is deep bluish-green, and it reduces the amount of light so much that the purchaser is pretty sure to return and want it changed. The dealer then replaces it with a pale yellowish-green. This the buyer brings back and says it is mistaken for an ordinary white light, when the change is made again back to the dark bluish-green. After a presentation of these facts, and an exhibition of the several signal glasses before the Board of Supervising Inspectors of Steamboats at Washington, they requested the Secretary of the Treasury to put in the hands of local inspectors standard red, green, and white glass, to which all lights on steamers must conform. These standard glasses are now being made, and bluish-green will be particularly avoided. All this applies equally well to the glass for railroad signals. Officials of all kinds have there made the mistake of supposing that a man reported by expert examiners color-blind by the worsted test, was not so or was not dangerous because he could distinguish these bluish-green glasses from the red. The red- or green-blind, of course, see blue and yellow as we do. Now a large glass company have lately, of their own accord, thrown aside all these bluish-green glasses, and manufacture at present only pure green, so convinced were they of the danger from
