Read it through once

The shield was the customary war-shield of his race, and would not be a protection to you or to me. It is no broader than a stovepipe, and is about as long as a man's arm. The opposing surface is not flat, but slopes away from the centerline like a boat's bow. The difficulty about a cricket-ball that has been thrown with a scientific “twist” is, that it suddenly changes its course when it is close to its target and comes straight for the mark when apparently it was going overhead or to one side. I should not be able to protect myself from such balls for half-an-hour, or less.