On the evening of the same day I examined the lower spur of the Riffelhorn. Amid its fissures and gullies one feels as if wandering through the ruins of a vast castle or fortification; the precipices are so like walls, and the scratching and polishing so like what might be done by the hands of man. I found evidences of strong polar action in some of the rocks low down. In the same continuous mass the action would sometimes exhibit itself over an area of small extent, while the remainder of the rock showed no appreciable action. Some of the boulders cast down from the summit exhibited a strong and varied polarity. Fig. 8 is a sketch of one of these; the barbed end of each arrow represents the north end of the needle, which assumed the various positions shown in the figure. Midway down the spur I lighted upon a transverse wall of rock, which formed in earlier ages the boundary of a lateral outlet of the Goerner glacier. It was red and hard, weathered rough at some places, and polished smooth at others. The lines were drawn finely upon it, but its outer surface appeared to be peeling off like a crust; the polished layer rested upon the rock like a kind of enamel. The action of the glacier appeared to resemble that of the break of a locomotive upon rails, both being cases of exfoliation brought about by pressure and friction. This wall measured twenty-eight yards across, and one end of it, for a distance of ten or twelve yards, was all north polar; the other end for a similar distance was south polar, but there was a pair of consequent points at its centre. [Sidenote: THE MAGNETIC FORCE. 1868.] To meet the case of my young readers, I will here say a few words about the magnetic force. The common magnetic needle points nearly north and south; and if a bit of iron be brought near to either end of the needle, they will mutually attract each other. A piece of lead will not show this effect, nor will copper, gold, nor silver. Iron, in fact, is a magnetic metal, which the others are not. It is to be particularly observed, that the bit of iron attracts _both ends_ of the needle when it is presented to them in succession; and if a common steel sewing needle be substituted for the iron it will be seen that it also has the power of attracting both ends of the magnetic needle. But if the needle be rubbed once or twice along one end of a magnet, it will be found that one of its ends will afterwards _repel_ a certain end of the magnetic needle and attract the other. By rubbing the needle on the magnet, we thus develop both attraction and repulsion, and this double action of the magnetic force is called its _polarity_; thus the steel which was at first simply _magnetic_, is now magnetic and _polar_.