MA

George Washington's concern over standardization of rifles for the Continental Army led to the formation of national armory and to his selection of Springfield as its site. Completed in 1794, it was the first national armory in the United States. Like the Robbins and Lawrence Armory, the Springfield Armory was an outstanding machining center for the design and mass production, employing notable engineers such as Thomas Blanchard (1788-1864), Thomas Warner, and Cyrus Buckland.

Designed, patented, and built by Thomas W.H. Moseley, this arched 96-foot span bridge preceded by years the standard use of wrought iron for bridges. For the first time in the United States, Moseley incorporated the use of riveted wrought-iron plates for the triangular-shaped top chord.

Minot's Ledge is a wave-swept rock formation in a rocky area of ocean about a mile off the Cohasset shore near Boston. Numerous serious shipwrecks prompted the government to erect a beacon there, and construction began in the summer of 1847.  

The light, constructed on tall iron legs, was put into operation on January 1, 1850. Designers believed that the water would flow freely through the legs, leaving the lighthouse intact. But a terrible winter storm toppled it in 1851, killing the two assistant keepers.  

The Old Mill, a smock type of windmill, believed to be the oldest operating windmill in the United States. Most of its parts are original. This mill is the sole survivor of four that once stood along the range of hills west of the town of Nantucket. The long spar and wheel rotate the top of the mill and turn the sails into the wind. Inside, visitors can watch the gears as corn is ground into meal, producing about 5 bushels an hour. Documentation of the restoration of the windmill is located at the Nantucket Historical Association's Research Center.

While the Erie Canal  has become well-known in the annals of American history, the Middlesex Canal, built two decades earlier and a model for canal engineers throughout young America, has only recently become recognized for its important achievements. Extending 27 miles northeast from Boston harbor to the Merrimack River near present-day Lowell, Masachusetts, the Middlesex Canal provided low-cost and efficient freight transport for almost five decades, helping to establish the canal in the U.S. as a viable means of economic development.  

This machine is an unusual triple-expansion, three-crank rocker engine, which in its day was a high-capacity unit providing outstanding performance for the Boston Water Works Corporation. Designed by Erasmus Darwin Leavitt, Jr. (1836-1916), Engine No. 3 was installed in 1894 to a high-service pumping facility on the south side of the Chestnut Hill Reservoir in Brighton.

Some of the station's notable achievements:  
The first method for detecting radioactive particles in water supplies  
A successful system of slow-sand filter beds for drinking water  
The landmark demonstration that microorganisms carried within filter media could degrade sewage 

The Charles River Basin was one of the pioneering environmental engineering projects in America. The project transformed 675 acres of unhealthy and unsightly salt marshes and tidal flats were into an environmental centerpiece for the Boston area by 1910. This was one of the first public projects to radically improve the environment and has served as a model for similar projects around the nation.