A case of apparent creation of structure, similar in principle to the foregoing, though more striking, is afforded by a network of squares, as in [Fig. 31], having sides parallel to this page, which gives the spectra shown in [Fig. 31]a, consisting of vertical rows for the horizontal lines and horizontal rows for the vertical ones. But it is readily seen that two diagonal rows of spectra exist at right angles to the diagonals of the squares, just as would arise from sets of lines in the direction of the diagonals, so that if the theory holds good we ought to find, on obstructing all the other spectra and allowing only the diagonal ones to pass to the eye-piece, that the vertical and horizontal lines have disappeared and are replaced by two new sets of lines at right angles to the diagonals.
Fig. 31.
Fig. 31a.
Fig. 32.
Fig. 32a.
On inserting the diaphragm, [Fig. 32], and replacing the eye-piece, we find in the place of the old network the one shown in [Fig. 32]a, the squares being, however, smaller in the proportion of 1 : √2, as they should be in accordance with the theory propounded.