[24]

Impenetrability of Layer of argillaceous sand to Light

Oct 7' 1878

Horace made 2 strips of wood on glass 1/10' & 1/20th of inch thick I filled up interspaces with same sand as used with Phalaris & syringed it with ether spray layer of 1/20' =.05 of inch quite opake when held up before clear sky.—

Even a layer somewhat under 1/20th opake.— 1/40th of inch = .0205. viewed in same manner was opake, But when the 1/20th of inch layer was viewed throw a long narrow tube certainly some slight light came through, but not through the 1/10' of inch layer.

[in margin:] When dry not more transparent

[24v]

[calculation not transcribed]

[25]

Oat

Heliotropism; showing some transmitted effect beneath Sand but no deep enough to be sure that no light penetrate sand— no, as .07 deep, we know that light does not penetrate much above 1/40th of inch; & the crusts considerably above 1/20th.

No	Width of crack	Depth of visible crack	Angle of underground stem
1	8/1000 inch	— [illeg] not measured	21°
2	24/1000	07 0.07 inch	vertical
3	24/1000	—	20
4	16/1000	—	not measured

 

I chose No 4 to measure pretty much by chance

Oats Oct 16 1878

A. pot of Oats exposed to SW. window at 8° a.m & examined at 4° 30' P.m.— Covered with the yellow sand— syringed with ether spray & I saw in close contact. —

In front or facing light (ie Opposite to furrow) the sand in cols close contact or a little heaped up.─