The equations of motion can be established in a similar way by considering the rate of increase of momentum in a fixed direction of the fluid inside the surface, and equating it to the momentum generated by the force acting throughout the space 5, and by the pressure acting over the surface S.
This was a yet further cause of the equating of the two parts of the sacred volume, which went on with an imperceptible crescendo through the first three quarters of the 2nd century, and by the last quarter was fairly complete.
This can be verified by equating to zero the five coefficients of the Hessian (ab) 2 axb2.
With this purpose in view, he not only notes carefully the length of the reign of each king in both kingdoms, but also (as long as the northern kingdom existed) brings the history of the two kingdoms into relation with one another by equating the commencement of each reign in either kingdom with the year of the reign of the contemporary king in the other kingdom.
But what was matter of immanent assumption with Erigena is in them an equating of two things which have been dealt with on the hypothesis that they are separate, and which, therefore, still retain that external relation to one another.