George and the Professor put in a great deal of time with the new team. Their knowledge of training, in view of the former experience with these animals, was such that within a week they could drive the yaks without much difficulty, although the new team was not by any manner of means as efficient as the lost one.
When the question of the kind of material for the guns came up, Harry was much concerned, as in making the barrels that length would necessarily greatly increase the weight.
"I think it would be better to make an alloy for your purposes," said the Professor, as they were discussing the matter.
"What is an alloy?"
"It is the combination of two or more metals."
"In what way does the alloy make it better than the hardest steel?"
"It is not hardness you want, but toughness. Metals have several properties, which are utilized for various purposes in the arts. Surprising as it may seem, wood has greater resisting power than diamond, and yet the precious stone is the hardest of all substances."
"But if we unite two metals are we not then making a new metal?"
"Not necessarily so. In the case of brass it is true. This is made by uniting two parts of copper and one of zinc. Both copper and zinc in themselves are very soft, and copper cannot well be polished in its pure state. Brass, however, is not only much harder, but is susceptible of a very fine polish."
"Are the alloys of all metals harder than the metals of which they are made?"