Looking for the Lost World

Two guns opened fire at the same time, and a cow grazing 50 meters away was hit three times in the back for no apparent reason. But the cow was not involved. Neither duelist was hit by the other. So what are the names of this pair of enemies? Not sure. If they knew, maybe they would be famous forever! But one thing I can tell you is that the older ones are British and the younger ones are Americans. However, I can mark the place where the cow just grazed, which is the junction of the United States and Canada, near a suspension bridge 3 miles on the right bank of Niagara Falls. This book is not only a popularization of science and technology, but also an ode to human exploration spirit and courage.