"Some of New Hampshire's most aesthetically pleasing yet least appreciated structures are stone arch bridges."
Designed by William A. Truesdell, a railroad engineer, the Seventh Street Improvement Arches celebrates the engineering application of mathematics to improve living conditions.
Alvord Lake Bridge, along with many of Ernest Ransome's reinforced concrete buildings, survived the 1906 San Francisco earthquake and several subsequent tremblers with no damage. Built in 1889 by Ernest L Ransome of New York, this reinforced concrete arch bridge in San Francisco's Golden Gate Park is believed to be the oldest concrete bridge in the United States that used steel reinforcing bars to improve the behavior of the concrete. The reinforcement consists of a series of square cold-twisted steel reinforcing bars, an invention of Ransome.
A 214-foot single-span covered wooden bridge, built above the cribs of stone in the AuSable River that served to break log jams and ice floes, collapsed during the winter of 1875 under the weight of a three-foot snowfall and high winds. The "Upper Bridge" (pictured) was built in its place.
The quantities of materials used in the building are staggering: 12,000 tons of structural steel; 42,000 cubic yards of concrete - consisting of 65,000 barrels of cement and 25,000 tons of sand; 360,000 feet of piling; and 10,000,000 bricks. At the time of its construction, Atlantic City Municipal Convention Hall was believed to be the world's largest hall, capable of seating 40,000 people. It continues to serve as a meeting place for shows, pageants, sporting events, and conventions. It is a structure of heroic proportions.
Ithamar A. Beard, an engineer of some prominence in New England, surveyed the mill brook and selected the best site for a storage dam. Contractor Simeon Cobb, knowledgeable of contemporary civil engineering practices, made major changes to the dam's original design, converting the linear dam into a gentle arch.