JAGGAR: EROSION AND SEDIMENTATION. 287 
aggradation, and delta building have been reproduced in miniature. 
Some account is here given of the history of these experiments, which 
have been carried on from time to time in the Harvard laboratory for 
eight years. In addition, the author’s last models are described in 
detail, as they illustrate the argument outlined above. 
Previous Srupres or Ritt DrAINAGE. The principal studies of 
rill pattern which have been made by geologists (Chamberlin and 
Salisbury, Nathorst, W. C. Williamson, Meunier) have been directed 
to their imitative character when preserved as fossil markings. In 
such a relation they frequently resemble organic forms. Daubrée 
(1879) believed many river systems to be controlled in development 
by faults and joints, and he has been followed in the United States 
by Hobbs (1901, 1905) and Iddings (1904) who seem to have a 
similar belief. Dodge (1894), from the physiographic standpoint, has 
Pointed out the similarity of beach rills to continental drainage. 
THE LABORATORY OF EXPERIMENTAL GEOLOGY (HARVARD UNI- 
VERSITY): PRELIMINARY EXPERIMENTS. The mechanical difficulties 
of realizing even beach conditions in a laboratory are great. Ground 
breaking studies of importance were made in 1899 in the Harvard 
laboratory by Dr. Ernest Howe, now geologist to the Panama Canal 
Commission. . In connection with experimental laccoliths Howe (1901) 
eroded domed surfaces of sand and marble dust with a coarse spray, 
and obtained radial drainage and infacing hog-backs. 
SEEPAGE Riris. In 1900-1901 the method was changed and in- 
Stead of etching the surface of a model with a spray, various devices 
Were used to produce seepage through a bank of sand. It was hoped 
that the phenomena observed on beaches might be duplicated. 
Tn Plate 1, fig. 1, there is shown a meandering stream produced by 
Seepage through a sand bank. A beach of sand was built on a suit- 
able metal pan and a trench was dug along the upper margin. The 
trench was kept full of water which soaked the model. The oozing 
Water gathered in two principal rills, which meandered from the time 
of their inception, and never showed any tendency to develop tribu- 
taries. The streams corraded profoundly even while meandering, 
and the complex terrace and distributary phenomena are part of a 
Process of planation (Gilbert) uninfluenced by change of tilt. 
In Plate 1, fig. 2, are shown the beginnings of digitation, coördinate 
With a meandering tendency. This stream, as in Plate 1, fig. 1, was 
