There is one question of great importance to inventors, and to which I have paid much attention, namely, the obtaining a spiral motion in a projectile which has been fired from a smooth bored gun. All we have witnessed goes far to prove that the attainment of this is impossible, in consequence of a principle not hitherto investigated by inventors. If the course of a projectile is changed from the straight to the spiral, it can only be done at the expense of range; and that for the following reasons: first, the force which is necessary to induce this spiral movement must be exerted at the expense of the force which propels it forward; secondly, when this spiral movement is acquired, it is so much in excess of the direct movement, that after advancing a certain distance it falls to the ground. A very simple experiment will prove this. Take an ordinary tin tube, cut a bullet of an elongated form--cylindro-conical if wished--having grooves from the point backwards, with the degree of spiral necessary to effect the object in view. Let the bullet be made of cork or light wood, such as can be projected by a blast from the mouth, and the result will be that the projectile will go one-half the distance before the friction of the atmosphere produces a motion on its axis parallel to its line of flight; from this point it gradually loses its velocity in a forward direction, it spins until its force is expended, and then falls vertically to the ground. To find the sequel, try the same experiment without grooving, and the range, with the same force, will be found to be double. Some years ago I witnessed such a trial with a 32-pounder; and, to the astonishment of all present, the bullet rose above the horizontal line, and then fell to the ground, like the cork bullet of which we have already spoken.