This Spectra-Physics model 1077 "Level-Eye" laser light detector was made in the early 1980s. After setting-up a laser-emitter a construction worker could use this detector to take readings and check for level on a job site. The unit has both a visual display and an audible tone to tell the worker when the detector is centered on the signal. It has two accuracy settings, plus or minus 1/8 of an inch or 1/16 of an inch.
Electricity pioneer Lewis Latimer drew this component of an arc lamp, an early type of electric light, for the U.S. Electric Lighting Company in 1880.
The son of escaped slaves and a Civil War veteran at age sixteen, Latimer trained himself as a draftsman. His technical and artistic skills earned him jobs with Alexander Graham Bell and Thomas Edison, among others. An inventor in his own right, Latimer received numerous patents and was a renowned industry expert on incandescent lighting.
Lasers have proven very useful in the construction industry. One example is this Spectra-Physics model 910 "LaserLevel" made in the early 1980s. In use, a construction worker attached the unit to a tripod and adjusted it so that it was nearly parallel to the ground. The level automatically completed the adjustment process when activated, and then emitted a beam of infrared light from a rotating head. The worker then moved to where-ever a measurement was needed and used a special laser detector to complete the task.
The "LaserLevel" self-adjusted if bumped slightly and completely shut off if bumped too much. The level operated automatically so it allowed one person to do work of two, resulting in cost savings since fewer assistants were needed.
Thomas Edison used this carbon-filament bulb in the first public demonstration of his most famous invention, the first practical electric incandescent lamp, which took place at his Menlo Park, New Jersey, laboratory on New Year's Eve, 1879.
As the quintessential American inventor-hero, Edison personified the ideal of the hardworking self-made man. He received a record 1,093 patents and became a skilled entrepreneur. Though occasionally unsuccessful, Edison and his team developed many practical devices in his "invention factory," and fostered faith in technological progress.
This scale model of Thomas Edison's Pearl Street power station was made in 1927. It demonstrates the internal arrangement of generating equipment and can be operated by means of a small electric motor in the base.
The first floor contained the boiler room and coal-handling equipment. Steam created by the boilers operated Porter-Allen horizontal steam engines on the second floor. The engines powered large Edison electrical generators nicknamed "Jumbo" after the famous elephant. Control and switching equipment were housed on the third and fourth floors.
The site for Edison's generating station had to satisfy both engineering and business needs. Because Edison used 100 volt direct current to power his new light bulbs, customers could be no further than ½ mile from the generator. But he needed a high profile location to promote the system. Edison chose a site in the heart of New York's financial district, 255 and 257 Pearl Street. On 4 September 1882, he threw a switch in the office of one of his main investors, J. Pierpont Morgan, and initiated service to the area.
A fire damaged the station extensively in 1890 but Edison and his men worked around the clock for 11 days to restore service. The station was taken out of service and dismantled in 1895, the building sold and later demolished. The New York Edison Company placed a commemorative plaque at the site in 1917.
Alfred Vail made this key, believed to be from the first Baltimore-Washington telegraph line, as an improvement on Samuel Morse's original transmitter. Vail helped Morse develop a practical system for sending and receiving coded electrical signals over a wire, which was successfully demonstrated in 1844.
Morse's telegraph marked the arrival of instant long-distance communication in America. The revolutionary technology excited the public imagination, inspiring predictions that the telegraph would bring about economic prosperity, national unity, and even world peace.