on the top of the magnet, and taking hold of the handle it will adhere sufficiently strongly to allow itself to be lifted up, so wonderful is its power of attraction. If you take a needle, and just draw one of its ends along one extremity of the magnet, and then draw the other end along the other extremity, and then gently place it on the surface of some water (the needle will generally float on the surface, owing to the slight greasiness communicated to it by the fingers) you will be able to get all the phenomena of attraction and repulsion, by bringing another magnetised needle near to it.
I want you now to observe that although I have shown you in these magnets that this double power becomes evident principally at the extremities, yet the whole of the magnet is concerned in giving the power. That will at first seem rather strange;
and I must therefore show you an experiment to prove that this is not an accidenta matter, but that the whole of the mass is really concerned in this force, just as in
