Transportation of Floating Sand. — Simgnds. 
35 
Greatest 
Greatest 
Thick¬ 
Weight. 
length. 
breadth. 
ness. 
1 . 
Pink quartz 5 mm. 
3.5 mm. 
1 mm. 
.0231 grins. 
2. 
“ “ 4 “ 
3 “ 
1 “ 
.0141 “ 
3. 
White quartz 4 “ 
4 “ 
3 “ 
.0304 “ 
4. 
“ “ 5 “ 
3.5 “ 
2 “ 
.0179 “ 
The specific gravity of each of the ingredients of “granite 
sand” of course exceeds that of water, that of quartz being 
2.5-2.8; of feldspar 2.44-2.62; of biotite 2.7-3.1. If these 
ingredients were present in the same proportions their aver¬ 
age specific gravity, i. e. the specific gravity of the sand, 
would be 2.54-2.84, or, say, 2.69. The specific gravity of that 
part of the sand under investigation which had actually 
floated was found to be 2.59. 
The attempt to explain the phenomenon, or possibly I 
should say phenomena, of floating sand from a physical stand¬ 
point involves the investigator in difficulty, so what I have to 
olfer is tentatively given with the hope that as physical re¬ 
search advances the subject may become better understood. 
When shaded, it will be seen that the floating sand grains 
cause a depression of the water’s surface, which, indeed, is 
quite as apparent in the case of isolated grains as in that of 
patches. 1 recall one instance where the depression, though 
of very short duration, possibly but a few seconds, was so 
great as to be positively startling. As I was sprinkling some 
sand upon the river, for experimental purposes, a pebble al¬ 
most as large as the end of my little finger fell into the center 
of a floating patch, which, to my great astonishment and de¬ 
light, was depressed, like a funnel, for, say, half an inch be¬ 
fore the cause of this unexpected phenomenon broke through 
its surface and sunk to the bottom. 
It appears from these arid other observations that the weight 
of the sand grains actually depresses the surface of the water, 
yet the elastic reaction of that surface is sufficiently great to 
prevent them from sinking, especially when the resistance 
offered by their angularity is taken into consideration. In 
the launching of grains the more rounded would tend to roll 
over in the water and thus become wet in consequence of 
which thej' would sink, while those of an irregular shape 
would overcome the tendency to roll and remain partially 
dry, thus fulfilling a condition necessary for floating. That 
