Fig. 15 gives an exact representation of the relative thickness of the mantles, and shows the general tendency to a thickening of the mantle at its upper extremity, designed to increase both the stability and striking power of the projectile. It will be noted that in general stoutness the Lee-Metford stands first, as the case increases gradually in thickness from base to apex. Beyond this it must be noted that the Lee-Metford is the only one of the four that is ensheathed with a mantle composed of a definite alloy, this consisting of 80 parts of nickel and 20 of copper. Two of the remaining bullets, the Mauser and Krag-Joergensen, are ensheathed with steel covered with a thin coating of an alloy of copper or cupro-nickel, to take the rifling of the barrel, while the third has a plain steel mantle which is covered with a layer of wax to take the place of the nickel used in the manufacture of the two others. It is interesting to mention here that the Boers evidently found the copper alloy coating insufficient for its purpose, or at any rate not satisfactory in preserving the weapon from the ill-effects consequent on the friction between the steel case and the rifling of the barrel, as at about the middle of the campaign they began to use their bullets waxed, as in the case of the Austrian Mannlicher; hence the legend of the poisoned bullets which caused such a sensation for a short period amongst the uninitiated. It is possible also that the additional layer of wax was necessitated by the wearing of the barrel. The wax employed for the Mauser bullets was not originally green. Mr. Leslie B. Taylor informs me that it is probably paraffin wax, the green colour depending on the formation of verdigris from the copper alloy with which the steel envelopes are plated. This completely corresponds with my own experience, since on the bullets in my possession the green colour, originally pale, has steadily increased in depth. Many old leaden bullets I found in the Boer arsenals were also waxed, but in this case no alteration in colour had taken place. The Guedes bullets, which are cased in mild steel, become somewhat brown with exposure from a similar oxidation or rusting of the surface.