of matter if matter represents the absence of mass, and thus the inversion of preconceived ideas is complete. Matter is measured by the absence of the mass necessary to complete the normal piling. And the effort to bring the negative inequalities together is also an effort on the mass to recede; and since the actions are those of positive pressure, there is no attraction involved, the efforts being the result of the virtual diminution of the pressures inwards, and in this inversion we have a complete, quantitative, purely mechanical explanation of the cause of gravitation.
13. Positive inequalities.
The explanations of the transmission of light and the cause of gravitation do not complete the explanation necessary to satisfy all the evidence.
Thus far we have sketched the efforts of negative inequalities only.
The efforts of the positive inequalities are the reverse of the negative inequalities, tending to separate the positive centres, and cause the positive inequality to scatter through the medium, thus dissipating any effects throughout the medium. Then, since the space occupied by inequalities is almost indefinitely small com-
