Part III.—Comparison of Ancient and Modern Practice.

The masonry of the temples of Greece and Egypt, and the ribbed vaulting of the mediæval cathedrals, not surpassed by any work of the present day.—Admirable design and workmanship of the old English timbered roofs, as Westminster Hall, Hampton Court, and Eltham Palace.—Constructive use of iron limited in early times.—Bituminous cement used in the East from the earliest times.—Concreted rubble masonry made with hydraulic lime greatly used by the Romans.—Three distinctive page 4 features of modern constructive science, viz.: 1. The use of cement concrete. 2. The introduction of wrought iron as a material for trussed beams. 3. The adoption of pneumatic apparatus for laying foundations under water.—Introduction of Portland cement; its use and abuse.—Cast iron beams.—Investigations by Mr. E. Hodgkinson and Mr. Fairbairn on the strength of cast and wrought iron.—Building of the Conway and Britannia bridges.—Abandonment of cast iron and introduction of wrought iron as a material for beams.—Differences between English and American practice.—Introduction of pneumatic caissons.—Caisson disease.—Dangers of the pneumatic process at great depths.

Conclusion.—List of subjects to be dealt with in the following twelve Lectures