For two hours longer they struggled upward; and then, within a few hundred feet of the summit, they could get no farther. In vain did they try every point that offered the faintest hope of success, and at last were forced to give it up. They noted the reading of the barometer, and with a few shavings and slivers cut from its outside case they made a tiny blaze, and, as Glen expressed it, boiled a thermometer in a tin cup.