paper, in which you can see there is nothing concealed, not even a trap-door. Well, if there was anything concealed from your view, you would be sure to see it." Laying the paper down and taking up the handkerchiefs, you continue, "In addition to the paper, I propose to make use of these three pieces of silk, or silk in pieces, commonly known as art white squares. I am afraid, however, some people would prefer to call them subdued white; possibly dirty white, if it were not for the liberty of the thing, but I know they call them art white in the stores, because I suppose they find they sell better."
Laying the handkerchiefs down, you take up the paper with the tube behind it, and, prior to forming the cylinder, remark:—"This experiment was suggested to me while in England traveling on the underground railway. I always travel by that line when possible, being fond of scenery. One day I had occasion to take a return single from Portland Road to King's Cross; and while passing through those tunnels I noticed that my linen changed color considerably, which suggested to me this illustration. With the piece of paper I will form a kind of tube or tunnel to represent for the time being one of those cavities on the underground railway."
