| and || | | | and
| | | |water.|| | | |water.
__________|______|______|______|______||______|______|______|______
| | | | || | | |
A | 1,370| 1,210| 100 | 1,310|| 3,175| 1,910| 150| 2,060
B | 1,170| 1,030| 200 | 1,230|| 2,700| 1,610| 290| 1,900
C | 970| 855| 290 | 1,145|| 2,250| 1,355| 430| 1,785
D | 775| 680| 370 | 1,050|| 1,800| 1,100| 570| 1,670
E | 590| 515| 460 | 975|| 1,350| 820| 710| 1,530
F | 400| 350| 560 | 910|| 900| 540| 860| 1,400
G | 190| 170| 650 | 820|| 450| 275| 1,000| 1,275
__________|______|______|______|______||______|______|______|______

FOOTNOTES:

[Footnote A: Presented at the meeting of May 18th, 1910.]

[Footnote B: _Transactions_, Am. Soc. C. E., Vol. LX, p. 1.]

[Footnote C: _Engineering News_, July 1st, 1909.]

[Footnote D: From "Gravel for Good Roads."]

[Footnote E: _Transactions_, Am. Soc. C. E., Vol. LXVIII, pp. 58-60.]

[Footnote F: "Discoveries and Inventions of the Nineteenth Century," by
Robert Routledge, Assistant Examiner in Chemistry and in Natural
Philosophy to the University of London.]

[Footnote G: _Engineering News_, January 15th, 1909.]

DISCUSSION

T. KENNARD THOMSON, M. AM. SOC. C. E.--Although the author
deserves great credit for the careful and thorough manner in which he
has handled this subject, his paper should be labeled "Dangerous for
Beginners," especially as he is an engineer of great practical
experience; if he were not, comparatively little attention would be paid
to his statements. The paper is dangerous because many will read only
portions of it, or will not read it thoroughly. For instance, at the
beginning, the author cites several experiments in which considerable
force is required to start the lifting of a weight or plunger in sand
and water and much less after the start. This reminds the speaker of the
time when, as a schoolboy, he tried to pick up stones from the bottom of
the river and was told that the "suction" was caused by atmospheric
pressure.

The inference is that tunnels, etc., in sand, etc., are not in any
danger of rising, even though they are lighter than water. Toward the
end of the paper, however, the author states that tunnels should be
weighted, but he rather spoils this by stating that they should be
w