The occasion was one in which everything depended upon promptness.

The tiger was likely to shift his position and turn his head so that the eyes would fail to show.
Jack reflected that there probably were a number of spots in the anatomy of the jungle terror that were more vulnerable than others; that a well-aimed bullet might be instantly fatal in one, while able to inflict only a partial wound in another.

Be that as it may, he was sure that a conical bullet driven between the eyes and through bone, muscle and brain by a rifle that could kill a man at the distance of a mile must do effective work when that brain was not a dozen feet distant from the muzzle of the weapon.

At any rate, there was no time for inquiry and he did not hesitate.
Aiming for a point midway between the gleaming orbs he pressed the trigger.

It takes a well-aimed weapon to kill a royal Bengal tiger, even at a short distance, but Jack's rifle was well aimed.