In "To Kill a Mockingbird", why does Judge Taylor have a gun on his lap when his wife comes home from church?in to kill a mockingbird

Judge Taylor was reading at home alone one night while his wife was at the church. He heard a scratching noise on his back porch. He got up to see what was causing the noise and found his screen door was open. He then saw a shadow of someone at the corner of his house but whoever was there got away. So Judge Taylor got a gun ready in case the stranger returned. The gun was still sitting on his lap when his wife returned from church.