156 On the Phantascope. 
Exp. 3.—Place two identical pictures of the same flower on 
the base-board, say they are an inch in diameter, and two and a 
half inches apart ; place also on the edge of the index area, a pic- 
ture of a small flower pot or vase, with flower stems as an index; 
then form the phantom image as before, and the flowers will ap- 
pear in the vase so long as you contemplate the stems at the in- 
dex screen, but the moment the eyes are directed to the flowers 
themselves, the phantom vanishes. ; 
4,—Let one of the above flowers be red and the other 
in the other is contemplated. If this be true, then the two eyes 
serve in the first place to fix the distance of an object by the 
amount of convergence, and in the next place to relieve each 
other by turns. 
Exp. 5.—Let there be a horizontal heavy line placed to the left 
and a vertical one to the right on the base-board, thus: — ) 
then adjust the screen and superimpose the images to forma 
phantom. That phantom will be a cross and the whole will ap- 
pear thus: — 
Exp. 6.—Do the same with any other parts of a figure of 
which one shall be the complement of the other; the phantom 
will be the complete figure. Thus take the picture of a person, 
cut it out of the paper, and cutting off the head, place the body 
on one side of the base-board, and the head upon the other, the 
converged phantom will be the complete figure, the head com- 
ing in from one side and the body from the other. It is per- 
haps unnecessary to say that each part must be placed in its true 
elevation, though displaced horizontally. It was in repeating this 
experiment, that I discovered that my eyes did not appear to be 
mates, for I saw the body clearly but the head obscurely. After 
a little time however, these conditions interchanged, and I saw 
the head clearly and the body obscurely. Nor did I seem to 
have any voluntary control over these conditions, but my eyes 
continued to relieve guard according to some rule of their own. 
This is rather an amusing experiment: the figure being beheaded, 
the phantom ghost appears between the two parts of the body, 
and from a little unsteadiness of the optical convergence, the 
ghost’s head is inclined to attitudinize, and will sometimes start 
off a little from the body, and in returning, will go a little too far 
and will break the neck in the opposite direction. If the head 
of the experimenter be a little inclined, then the head of the 
phantom will come on too high or too low. ' 
