I put up my gun to fire, but seeing my friend's head right in the way and in a line with its muzzle, I waited a second, but the deer was gone.

I had scarcely got over my disappointment when I heard the branches breaking in the wood very near to me, and suddenly a deer sprang right over my head, taking a flying leap, like a hunter would do over a fence.
This unusual action on the part of the deer called for unusual action on my part.

As he had taken a flying leap over my head, I took a flying shot at him a second before he landed on the other side of me.

The result was that he rolled over like a rabbit, shot _from underneath_ through the heart.

This deer proved to be a very fine specimen of the fallow, every point showing him to be of that species, except his antlers, which were quite straight.