It was a matter of angles when it was desirable to come down to a close calculation, and the young commander found his trigonometry very useful, and fortunately not forgotten. With an apparatus for taking ranges he had procured the bearing of the highflyer accurately as soon as the last course was given out, perhaps half an hour before. He took the range again, and found there was a slight difference, which was, however, enough to show that the form of the triangle had been disturbed.