firm gravel is limited to from 4 to 6 tons. The writer's practical
observations have convinced him that it is frequently much safer to put
four times 6 tons on a square foot of gravel than it is to put
one-fourth of 2 tons on a square foot of soft clay.

In connection with the bearing power of soil, the writer also believes
that too little study has been given to the questions of the lateral
pressure of earth, and he desires to quote here from some experiments
described in a book[F] published in England in 1876, to which his
attention has recently been called. This book appears to have been
intended for young people, but it is of interest to note the following
quotations from a chapter entitled "Sand." This chapter begins by
stating that:

"During the course of a lecture on the Suez Canal by Mr. John H.
Pepper, which was delivered nightly by him at the Polytechnic
Institute in London, he illustrated his lecture by some experiments
designed to exhibit certain properties of sand, which had reference
to the construction of the Suez Canal, and it is stated that though
the properties in question were by no means to be classed among
recent discoveries, the experiments were novel in form and served
to interest the public audience."

Further quotation follows:

"When the Suez Canal was projected, many prophesied evil to the
undertaking, from the sand in the desert being drifted by the wind
into the canal, and others were apprehensive that where the canal
was cut through the sand the bottom would be pushed up by the
pressure on the banks * * *.