^{page 574 note 1} I feel bound to notice the sjtrange way in which Col. Greenwood has so often used my name alone in his letter, without any reason, as the paper he notices is the joint work of Mr. Bristow and myself.—W. Whitaker.

^{page 575 note 1} Published in the Proc. Inst. Civ. Eng.

^{page 575 note 2} Published in the Papers of the Royal Engineers. We are away from books, and so cannot give references exactly; indeed, we have not even a copy of our own paper with us, nor of “Uain and Eivers”

^{page 575 note 3} We readily acknowledge the good work done by Col. Greenwood in illustration of this subject.