Epigraph
The writer wishes to acknowledge his appreciation of the assistance given him by Mr. Jas. D. Schuyler, M. Am. Soc. C. E., Consulting Hydraulic Engineer, in reviewing this paper, and in making suggestions of value. Appendix II contains a list of authors whose writings have been freely consulted, and to whom the writer is indebted; the numerous citations in the body of the paper further indicate the obligations of the writer.