Just as a blow made with great slowness over the length of its contrary motion returns with more travel and thereafter a greater blow, while that which is of continuous and brief motions is of little force, so too is study upon one and the same matter made with long intervals of time. The judgement has become more perfect and better judges its own error. And the eye of the painter does the like by drawing back from his painting.

The motion of the weight suspended from the balance, made along the length of that balance, will become the lighter the more the weight moves out beyond its perpendicular.

Every body of unequal shape has 3 centres, of which the first is the centre of natural gravity, the second of accidental gravity, the third of its magnitude. And if, for the sake of argument, there were more, they all answer to these. The centre of natural gravity is that where, in whatever direction the weight is cut with a straight cut passing through the said centre, the weight remains divided into 2 equal parts. The centre of accidental gravity is that where bodies are suspended in the position of equality, which bodies, cut with a straight cut through those centres, will divide the body into two unequal parts. The centre of magnitude is that which divides the body into 2 parts of equal length. In bodies of uniform shape and weight the centre of natural gravity, of accidental gravity, and of magnitude are in one and the same place. The arms of the balance are of 2 natures, of which the first is real, the second potential. Real is when those arms are visible and palpable; potential is when those arms are invisible and impalpable.

d. The junction of the appendicle with the real arm of the balance will never be right-angled. The junction of the appendicle with the potential arm will always be right-angled. The angles of the junction of the appendicle with the real arm will not be of equal height unless the appendicles are laden with equal weight. The distances that the angles of the junction have from the real arms of the balance will have among themselves the same proportion as that of the weights and of those real arms.

The angle of junction is that contact which the appendicles have with the arm of the balance, whether real or potential. The real and potential arms of the balance are called those very short spaces enclosed between the attachment of the appendicles to those arms and the centre of the pole of the balance.

The weights attached to the appendicles are wholly along the whole lengths of those appendicles, and wholly in every part of those lengths. Therefore we may say those weights to be all in the attachment of the appendicle to the arm of that balance, both the real arm and the potential, because all such weights answer to their attachment. The junction of the potential arm with its appendicle will always be right-angled, and the junction of the real arm with its appendicle will always be acute. And conversely: the junction of the real arm with the appendicle will never be right-angled. The appendicles of the balance are real and potential, joined together. The appendicles of balances have reality and potentiality joined together. Each of the arms of the balance is double, of which one is real and the other potential, and they are set in different, distant positions with their ends apart from one another, and they are of various lengths. The potential and real arms are born from the centre of the balance and terminate in the appendicle of the weight attached to that arm. That angle of the real junction which the arm of the balance makes with its appendicle will be the more acute, the less weight it sustains than the weight given to the opposite arm.

Those bodies will have the centre of natural gravity, of accidental gravity, and of magnitude in one and the same place which are of uniform shape and weight. The angles of the appendicle of the pole of the real balance are always right. The angles that the junction of the appendicle of the potential balance makes are always obtuse.

Equal weights on equal real arms make the angles of the junction of the appendicles equal. Unequal weights on unequal real arms make the angles of the junctions of unequal heights. The weights attached to the appendicles are wholly along all those appendicles and wholly in every part of their lengths. The angles of the real junction will have in their sizes the same proportion as that of the weights joined to those arms.

The real and potential arms are in those spaces enclosed between the appendicles of the weights and the centre of the balance. Never do the lengths of the potential arms... The potential arm is always shorter than the real arm. The real and potential arms of the balance are very short straight lines, born at the centre of the balance and terminating in the appendicles of the weights. The angle of junction is that where the appendicle of the weight joins with the real or potential arm of the balance.