The lecture with which Professor Faraday wound up the course at the Royal Institution may be mentioned here, seeing that it adds somewhat to our knowledge of the theory and phenomena of magnetism. As usual, the lecture-room was crowded; and those who could not understand, had at least the satisfaction of being able to say they were present. Mr Faraday, who, enlarging upon his view, announced, a short time since, that there are such things as magnetic lines of force, now contends that these lines have a 'physical character'--a point most satisfactorily proved by sundry experiments during the lecture. The inquiry is one, as Mr Faraday observes, on the 'very edge of science,' trenching on the bounds of speculation; but such as eminently to provoke research. The phenomena, he says, 'lead on, by deduction and correction, to the discovery of new phenomena; and so cause an increase and advancement of real physical truth, which, unlike the hypothesis that led to it, becomes fundamental knowledge, not subject to change.' A chief point of discussion to which the investigations have led is: Whether the phenomena of what we call gravity may not be resolvable into those of magnetism--a force acting at a distance, or by lines of power. 'There is one question,' continues Mr Faraday, 'in relation to gravity, which, if we could ascertain or touch it, would greatly enlighten us. It is, whether gravitation requires _time_. If it did, it would shew undeniably that a physical agency existed in the course of the line of force. It seems equally impossible to prove or disprove this point; since there is no capability of suspending, changing, or annihilating the power (gravity), or annihilating the matter in which the power resides.' The lines of magnetic force may have 'a separate existence,' but as yet we are unable to tell whether these lines 'are analogous to those of gravitation, acting at a distance; or whether, having a physical existence, they are more like in their nature to those of electric induction or the electric current.' Mr Faraday inclines at present to the latter view. He 'affirms' the lines of magnetic force from actual experiment, and 'advocates' their physical nature 'chiefly with a view of stating the question of their existence; and though,' he adds, 'I should not have raised the argument unless I had thought it both important and likely to be answered ultimately in the affirmative, I still hold the opinion with some hesitation, with as much, indeed, as accompanies any conclusion I endeavour to draw respecting points in the very depths of science--as, for instance, one, two, or no electric fluids; or the real nature of a ray of light; or the nature of attraction, even that of gravity itself; or the general nature of matter.' These are profound views; but we may reasonably conclude, that, however obscure they may at present appear, they will in time be cleared up and further developed by the gifted philosopher from whom they emanate.