24 Mr. White’s Design for the New London Bridge,

The seventh pier (G) had of Atkinson’s Roman cement onepart, pure sand one part. Weights being carefully and suc-cessively applied at A, half-hundred at a time; it supportedfive hundred weight, and broke under five hundred weightand a half at B. On examining the separated parts, it wasevident that the mortar had not equally adhered to everybrick.

The longest end being tried in the same way as in the firstexperiment, viz.

3 feet.

It was left nearly half an hour with one ton weight at A, andbroke in consequence of a shock it experienced by the break-ing of the pier subjected to the next experiment.

In the eighth pier(H)the cement was composed of four partspozzolano, and one part air-slaked stone-lime. This broke inlaying down. A second experiment was made as in the pre-ceding pier; it supported five hundred weight and a half, andbroke in two pieces.

The ninth pier, built of rough lumps of pozzolano, in imita-tion of Roman walling, nine parts pozzolano and one and al.alf part s tune-lime, was not sufficiently dry to be experi-mented upon.

Continuation of Experiment, No. II. May \9th .—Twowrought iron wedges were driven with sledge hammers at

two points equidistant from the centre of a transverse line

bisecting