confess that isolated experiments will not lead to the object in view. For this purpose, well followed up experiments, directed by the knowledge, zeal, and the means at the control of a scientific body, are necessary. I do not believe that Europe can offer elsewhere a union of circumstances so favourable for grand scientific enterprises as is presented by the illustrious Imperial Academy. I submit my desire to advance experiments in magneto-electricity to this distinguished body, whose endeavours are directed to the enlargements of the limits of each branch of science in which it engages, and to extend its boundaries.
We have no right to suppose that the limits of the magnetic power which soft iron is capable of acquiring, are narrowly restricted, or that they have ever been attained by experimentalists. I have made on this subject an experiment which is not without interest. The ends of the helix surrounding the horse-shoe I have described (Art. 9), were placed in contact with a battery of 16 pairs of 72 square inches, recently constructed, and charged with nitro-sulphuric acid (27). The armature, which weighed 3 lb., was placed horizontally, and at a distance of 5 inches below the extremities of the horse-shoe. As soon as the circuit was completed, this armature raised itself and sprung with such violence towards the ends of the magnet, that we might, without exaggeration, estimate the force as equal to that acquired by falling 15 to 20 feet. The result of a second experiment was somewhat less, and after repeated experiments it was necessary to diminish the distance to within two to three inches, to cause the armature to spring towards the magnet with so powerful an energy. This beautiful experiment deserves being repeated, but for its success a fresh and powerful battery is necessary. For the present, we must be content to measure in one way or another the mechanical force of the magnetism, or the useful work at our disposal, in the case of the attraction of the armature. The mode of operation of this force renders it very difficult to find an exact measure to express the effects, due for the most part to the active power produced by an accelerating force, the law of which is not exactly known.
With respect to the state of magnetic saturation, we shall never attain it, unless by augmenting at the same time the intensity and number of the currents, to the influence of which the
