Rudolf Eickemeyer developed his "ironclad" dynamo in the 1880s. The unique method of construction--its heavy iron field coil construction and iron sheathing--gave the dynamo its nickname. It was compact, rugged and efficient, though the ironclad design made it difficult to cool. This dynamo supplied power for the lighting system and small motors at the Haxton Canning Company in Oakfield, New York for 15 years.

When Boston's North Union Station opened in 1893 it required a central power station to supply electricity to light the massive train shed and terminal and to operate turntables and machinery. At the station's Minot street powerhouse, electrical engineers monitored power usage. This ammeter--used to measure the strength of an electrical current--was one of many switches, circuits and meters found in the power plant.

The Fort Wayne Electric Corporation had manufactured arc lamps, dynamos and other lighting and electrical equipment since 1881. By 1894, the company had survived financial difficulties, a corporate reorganization and a recent name change. Aided by well-respected electricians, engineers and inventors, the company expanded and increased its production efforts. This photograph shows the area were electrical meters were made.

The Fort Wayne Electric Corporation attracted many talented electrical engineers and inventors. Among the well-known names were James Wood and Thomas Duncan. Wood was in charge of manufacturing the electrical apparatus and licensed many of his patents to the company. Duncan, an inventor in his own right, was head of the company's laboratory and testing department. He signed the standardization form adhered to the back of this ammeter.

Switches open or close an electrical circuit to turn things off or on. Knife switches, such as this one, were commonly used on power and lighting switchboards or connected to a motor or generator. This switch was used on Sugar Island in the Detroit River in the early 1900s. The island's powerhouse provided electricity for a dancehall, amusement rides and other amenities.

Safety switches, such as this one, were developed to prevent dangerous arcing and limit a worker's exposure to current-carrying parts--and potential injury. Safety switches enclose exposed parts and require an operator to turn off the current before opening the switch boxes.

Companies that built and sold equipment to generate, distribute, and monitor electric power created product literature to sell their goods. In 1902, General Electric produced this catalog for companies that decided to install onsite power stations. General Electric was formed when two of the leading manufacturing companies of electrical equipment--Edison General Electric Company and Thomson-Houston Company--merged in 1892.

The Sprague Electric Railway and Motor Company created this motor for the Richmond Union Passenger Railway in 1887. Most streetcar systems at this time, like the one in Richmond, Virginia, relied on horses or mules to move people. Richmond's new 12-mile streetcar line--effectively powered by motors like this one--became the first successful large-scale electric street railway system and the prototype for future systems in other American cities.

Francis Crocker teamed up with Schuyler Wheeler to form Crocker-Wheeler Electric Motor Company in 1888-89. Their company manufactured motors for use in factories, small shops, offices and homes. Their motors powered lathes, presses, and drills and ran elevators, fans, and sewing machines. The two men were well-respected engineers, both serving as president of the American Institute of Electrical Engineers.

Electric motors revolutionized manufacturing in the late 1800s. Motors, driving groups of machines, began to free production from the tangle of belts, pulleys and line shafts previously used to power equipment. Factory space became open and flexible, safety improved, and production increased. Northern Electrical Manufacturing Company, founded in 1895 in Madison, Wisconsin, specialized in factory motors, generators, and other machinery.

Companies began producing small electric motors in the late 1800s to power household appliances like electric fans. The first fans, driven by direct current motors, were bulky and potentially dangerous due to exposed electrical components and blades. Advancements in motor technology--specifically the reliable, compact alternating current motor--and inexpensive electrical power made fans available to a growing number of Americans.

Rheostats vary the amount of electrical resistance in a circuit. They proved beneficial as the use of electrical power expanded in the late 1800s. Among their many applications, rheostats helped motors start safely, controlled motor speed, maintained a constant current in battery chargers, and adjusted volume and light levels.

Companies that generated and distributed electrical power in the late 1800s needed equipment to monitor and measure output. Apparatus used in scientific laboratories proved insufficient. Electrical engineers needed robust, rugged and portable instruments that they could read quickly without performing complex calculations. William Ayrton and John Perry developed this direct reading voltmeter among other measuring instruments for the new industry.

Nineteenth-century scientists and electrical engineers devised various meters to monitor and measure electrical output. Voltmeters, ammeters, and wattmeters became vital tools in the generation and distribution of electrical power, as well as scientific experimentation. Elihu Thomson, a prolific inventor and co-founder of the Thomson-Houston Electric Company, along with E. W. Rice developed this portable, accurate and affordable voltmeter.

Transformers increase or decrease voltage and are essential to alternating current (AC) power systems. In the late 1800s, with the help of transformers, AC power systems proved more efficient and economical than their direct current competitors. Transformers helped convert electricity to high voltage for transmission across long distances, then reduced it to lower, safer voltages for use in homes and factories.

In the late 1800s, companies began producing electricity to light cities, run streetcars, and power factories, homes and offices. A potential danger to this power system and its apparatus was lightning and other large discharges of electricity. A lightning arrester diverts the surges and protects valuable equipment from damage.

This lightning arrester made by Westinghouse Electric Company was patterned after one patented by Paul Winsor and Alexander Wurts in 1889. Wurts was one of the leaders in lightning arrester development.

To make money selling electricity, Thomas Edison had to know how much his customers used. This meter used electricity to plate zinc onto electrodes. By weighing the electrodes to see how much zinc had accumulated, Edison's company could calculate how much electricity was being used. This meter was used as part of Edison's first three-wire distribution system in Sunbury, Pennsylvania.

Oliver B. Shallenberger, chief electrician at Westinghouse, invented the first successful AC ampere-hour meter in 1888. This meter measures the flow of electric current through a circuit. Early meters like this helped companies that supplied electricity to customers monitor usage and charge appropriate rates. Shallenberger's meter also paved the way for the acceptance of AC power distribution.

Elihu Thomson, engineer, inventor and cofounder of the Thomson-Houston Electric Company, developed a commutator-type wattmeter in the late 1880s. His recording watt-hour meter helped transform the nascent electric power industry. The sturdy device provided companies that supplied electricity to consumers a way to accurately track and bill electrical power use. General Electric, which produced this type of meter, produced this price list.

In the late 1800s, companies that supplied electricity to consumers needed a way to measure how much customers used -- and then charge them accordingly. Inventive electrical engineers developed various methods to measure electric power. Induction meters that employed magnetic fields to rotate a disc or cylinder to register energy usage would become the standard. Continued improvements made these wattmeters more compact and reliable.

Induction-type wattmeters proved reliable and would become the industry standard, but until 1910 Westinghouse held the patents. Sangamo Electric Company, which had not been granted a license from Westinghouse, produced this mercury-motor alternative.