JAGGAR: EROSION AND SEDIMENTATION. 293 
Coarse spray model illustrated by Plate 3. The desideratum would 
be a model of some very fine material like clay, with an impalpable 
but continuous moistening of the surface, and sufficient thickness to 
5 , 
permit the development of a distinct relief under erosion from the 
resulting rills. 
MODELS SPRAYED WITH ATOMIZERS. Such conditions were finally 
realized by using the finest kind of crushed rock —slimes from a 
Stamp mill —and spraying with atomizers. The atomizers used were 
the ordinary bottle style used in a barber-shop. Air pressure was 
maintained at about 10 pounds (ca. 4.5 kg) per square inch (625 
«600000000000 00008” 
sig 
£2 2000000 000% 
Fig. 1. Electric Air Compressor. 
sq. mm.) while two atomizers were in operation. The/apparatus for 
compressing the air is shown in Fig. 1. A % h. p. electric motor 
operates a single-cylinder air-pump. The air is compressed in a five- 
foot tank provided with pressure gauge and an automatic shut-off 
valve which may be adjusted to stop the motor at any required pres- 
sure and start again when pressure.is reduced. A rubber tube from 
the tank carries the air to the atomizers which are each provided with 
independent cocks. This apparatus may be obtained of dealers in 
barber’s supplies. 
A model of slimes was built + as follows:— a plate of glass 63 X 83 
inches (.165 X .216 m) rectangular was placed on the bottom of a 
deep ash-pan. A quantity of the slimes was stirred in water and the 
1 The laboratory work of this and the last experiment was done by Mr. H. G. Fergu- 
Son, now government geologist in the Mining Division, Bureau of Science, Manila, P. I. 
