Mr. Whitworth, like General Jacob, has had to sacrifice scientific economy in order to obtain the points he required. I have already dilated upon the truism that all projectiles range with the greatest economy which have the centre of gravity in the head or fore part of the bullet. I have also pointed out the fact that the elongated projectiles which have not the centre of gravity in the head, turn over during their flight after leaving the muzzle of the gun; and this is also found to be the case in rifles having a greater degree of spiral than the Enfield, one turn in six feet 6 inches. To meet this difficulty, therefore, General Jacob adopts one turn of spiral in every three feet: thus his bullet in passing out has double the friction of the Enfield; and when we look at the fact that he is further compelled to increase the length of his bullet to 2-1/2 diameters, a little reflection will point out the entire want of economy in his whole arrangement. On turning to the Whitworth, we find that, in order to ensure his bullet keeping point foremost in its flight, he has to double the very great spiral adopted by Jacob: thus we have all its concomitant disadvantages, friction, expenditure of matter, and danger of bursting the gun. When we contemplate such arrangements as exist in these two guns, it must be evident that they are both self-destructive. No system of projectiles can be durable which is effected by straining all the acknowledged principles of mechanics; and this has been done in each of these cases. The scientific world knows well that a much higher rate of speed can be attained in railway travelling than is daily practised; but they also know that it can only be obtained in the same way as Jacob and Whitworth obtained their range in gunnery: namely, by an excessive expenditure of fuel, and a wear of engine amounting to comparative destruction; whilst, at the same time, the danger is so much increased that it would be folly and recklessness to persist in such a course. The question, therefore, resolves itself into this; that in locomotion and in projectile science, if we would have them perfect, we must study the mode of obtaining the greatest results with the least expenditure of means. Facility of loading must at all times be of great importance: the soldier cannot have the means of cleaning his rifle when in action, and yet if the hexagonal principle were to be adopted, it must be repeatedly cleaned, or it would be almost impossible to load it, and when discharged it would either burst or its fire would not be effective. During such a war as that in India, going on day and night, a soldier could not be expected to wash out his rifle after every half-dozen shots.