XVII. It may perhaps be answered to this, that the threads in twisting them together might be stretched and made finer, and their strength weakened; and that besides this, they might have been strained by supporting the weight in the first instance; but this objection, although specious, is insufficient; for by attending to the relation of this matter in the History of the Academy Royal, we shall find, that by order of the Academy, another experiment was made in a quite opposite way, for a small silk cord which supported a little more than five pounds, was afterwards untwisted, and they found that the single threads among them all sustained six pounds and a half. XVIII. The true cause of this phenomenon in my judgment, is, that the threads in the twisted cord do not bear equally alike, because it seems to me morally impossible in the twisting, to preserve the exact length or bearing of all the fibres, but that some of them must be more tense or tight, and some of them more slack than others; in consequence of which, the bearing of some must vary more from the perpendicular or central line of gravity, than that of the others, and that some part of them are upon the stretch, and others rather slack at one and the same time. From hence it follows, that the weight at first is not supported by all the fibres, but only by those which are the most tense, and the least distant from the central line of gravity, which not being of themselves sufficient to resist the strain, give way, and that the weight afterwards falling upon the others, they do the same; and that this is the case may be evidently seen, by observing when more weight is hung to a rope than it is able to sustain, it does not break instantly, but successively, and although the total separation is performed in a very little time, there is space enough before it is compleated, for us to perceive, that some threads break first, and others afterwards. XIX. But although my opinion should not exactly coincide with the experiments made in the academy, I conclude, that the judgment we should make of this matter is, that both in this, and all other physical agents, virtue united is the same that it is separate; for the cord breaking with a less weight than the threads sustained separate, did not result from these last being stronger separate than they were united, but from the fibres of the threads acting more together in their separate state, than they did in their united one, as in the last case, the resistance of the fibres to the force, was made more in succession than it was in the first; or to speak more properly, although the threads were united in the cord, their power or virtue of resistance to the force, was not united or exerted together. PARADOX VI. _The Sun in consequence of its own proper Nature, and intrinsic Disposition, heats and enlightens unequally at different Times._ SECT. VI.