23

on the Principle of Cementitious Architecture.

21st and 23rd of April, in a vertical position, and of the fol-lowing dimensions ; namely, six feet high, and about fourteeninches square.

The cement of the first pier (A) which was tried was of purefresh Roman cement, and was accidentally broken in layingdown, at a place where the cement had partially set in the jointof brick-work, before the adhesion had taken place. A frag-ment of the pier, three feet six inches in length, being laiddown as here represented,

A

30 inches.

was carefully loaded at A with weights, a half-hundred at atime; it supported eleven hundred weight, and broke undereleven hundred weight and a half.

The cement of the second pier (B) was composed of threeparts pozzolano, and one part stone-lime, reduced to putty ascommon mortar. This pier was similarly placed in the sup-ports; it broke in the middle; and a fragment was similarlyloaded, when it supported four hundred weight, and brokeunder four hundred weight and a half.

The cement of the third pier (C) was composed of threeparts pozzolano and one part stone-lime, ground and fresh.This pier broke in turning it round, and the fragment waslaid by for further experiments.

In the fourth pier (D) it was composed of three parts puresharp sand, and one part stone-lime. This pier broke intothree pieces on attempting to lay it on the supports.

In the fifth and sixth piers (EF), it was composed of three

A

If

.4 feet.

parts sharp washed sand, and one part chalk-lime; they'crumbled to pieces on attempting to place them.

The