That the young trappers may understand what are the requisites of a good trap we will describe in detail one that has held its own in the estimation of the professional trappers for sixty years, and then we will endeavor to point out wherein the many so-called "improvements," that have been put on the market, have uniformly failed of success.
What the main spring is to a watch, a trap spring is to a trap, and unless the spring is made of a properly compounded steel and is of the right form and proportion and correctly tempered it will surely fail and make the whole trap worse than useless.
Certain mixtures of pig iron are used in making spring steel and if these mixtures are varied from in any particular or if the steel has a surplus of carbon, or is deficient in that element, it will not take a proper temper and consequently is of no value. A proper manipulation in the rolling mill is also necessary, or the steel may be entirely ruined in rolling.
A good spring when set should show a nearly uniform curve throughout. This indicates that it is properly tapered so as to bring a uniform strain on the steel. The lasting qualities of a spring are greatly dependent on the correctness of this point.
A WELL MADE TRAP.
The "bows" or holes in the spring must be of a proportion to properly fit the jaws and have such a "twist" as will allow them to lie flat when set, and the temper must be so moderated as not to be brittle or "high", otherwise they may break if sprung without anything between the jaws. For it is well known that it is a much harder strain on any trap to be sprung thus than to snap on to the leg of an animal.
Another very important thing is to have the strength of the spring proportioned to the size of the trap, for an excessively stiff spring is more apt to break the leg bone of the animal and increase the liability of "legging" as the trappers call it, while a very weak spring may allow a vigorous animal to draw its foot out, especially if caught low down.
And last but more important than anything else, the spring must have just the right temper, for a bad tempered trap spring is like a bad tempered wife, a worse than useless encumbrance. And do not let the tyro imagine that it is easy to temper a trap spring, for it requires a long experience and very expensive and carefully studied conditions and apparatus to produce anything like uniform results.