Having so done, he backed his horse from the river, until he came to where his eye told him that he had obtained the point of an equilateral triangle.
Thus, in the diagram he selected the two trees, A and B, walked back to E, and there fixed his lance.

He then fell back in the direction E D, until he had, as nearly as he could tell, made the distance from A E equal to that from E D, and fixed another lance.

The same was repeated to E C, when the last lance was fixed.

He then had a parallelogram; and as the distance from F to E was exactly equal to the distance from E to G, he had but to measure the space between the bank of the river and E, and deduct it from E G, and he obtained the width of the river required.
[Illustration] I do not think that this calculation, which proved to be perfectly correct, occupied the old chief more than three minutes; and it must be remembered that it was done in the face of the enemy.

But I resume my own history..