The cables needed to transmit electrical power may seem simple but are actually complex technological artifacts. Modern cables inherit the lessons learned during more than a century of research and experience. This power cable was described by GE engineer William Clark in 1898 as follows: “1,000,000 [circular mil] cable composed of 59 wires, each .1305" in diameter, containing two insulated pressure wires each 2500 C.M. area, the whole insulated with saturated paper 5/32" thick and finished with lead 1/8" thick. This is a feeder cable for circuits not exceeding 2000 volts working pressure on Edison three wire circuits."
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.
The term “home-made laser” almost seems a contradiction but that is not the case. This gas laser was built by high school student Stephen M. Fry in 1964, only four years after Ali Javan made the first gas laser at Bell Labs. Fry followed plans published in Scientific American's "The Amateur Scientist" column in September 1964, (page 227).
The glass tube is filled with helium and neon and, as the magazine reported, "seems to consist merely of a gas-discharge tube that looks much like the letter 'I' in a neon sign; at the ends of the tube are flat windows that face a pair of small mirrors. Yet when power is applied, the device emits as many as six separate beams of intense light."
The discharge tube is the only piece of this particular laser that remains. The flat windows (called "Brewster windows") are square instead of round, and the electrodes are parallel to the gas tube instead of perpendicular. Otherwise it resembles the drawings in the magazine. Fry later earned a Ph.D. in physics with a dissertation on lasers.
Invented by Walther Nernst, this incandescent lamp could operate in open air and did not violate Edison’s patents. The housing is sectioned for study of the internal ballast resistance mechanism. The glower consists of three iron rods coated with rare-earth elements. The coating gives off light when heated and protects the rod from oxidation.
Luminous Sign with helium gas designed by Perley Gilman Nutting (1873–1949) and made by Edward O. Sperling at the National Bureau of Standards. Exhibited at the St. Louis Exposition in 1904.
Description
Label found with object reads: "Luminous Sign Designed by P. G. Nutting / Made by Sperling / National Bureau of Standards / Exhibited at St. Louis Exposition 1904".
From Rexmond C. Cochrane, Measures for Progress: A History of the National Bureau of Standards (Washington, D.C., U. S. Dept. of Commerce, 1974), 83.
“When free from Exposition commitments, the electrical staff carried out considerable routine testing and even some research in its Palace laboratory. More a novelty resulting from Nutting's gas spectra work than a piece of serious research, however, were the luminous script signs in glass tubing exhibited by the staff at the fair. When excited by electric discharges, the noble (inert) gas in the tubes—it was neon—lit up with a reddish glow.”
Note 59: “Dr. Nutting's neon signs—two special glass tubes blown by Mr. Sperling in the Bureau shops, one reading "HELIUM," the other "NBS"—resulted from a modification he made in the laboratory instrument known as the Plücker tube and reported in NBS Scientific Paper No. 6, "Some new rectifying effects in conducting gases" (1904). The Plücker tube, like the earlier Geissler tube, was used in the study of spectra of gases and metals. By substituting or disk aluminum electrodes for the thin platinum wire in the tube, Nutting obtained a much steadier and brighter light. Although never made public, the neon phenomenon has long been considered the Bureau's first notable laboratory accomplishment, and the forerunner of modern neon signs and fluorescent lamps. Interview with Dr. William F, Meggers, Aug. 4, 1964.”
Invention rarely stops when the inventor introduces a new device. Thomas A. Edison and his team worked to improve his electric lighting system for some years after the initial introduction in 1880. This lamp shows changes made after about ten years of labor aimed at lowering costs and increasing production. The simplified base required little material; the diameter and thread-pitch are still used today. The filament was changed from bamboo to a treated cellulose, based on an invention by English chemist Joseph Swan. The bulb was probably free blown by Corning Glass Works, but would soon be replaced by a bulb made by semi-skilled laborers blowing glass into iron molds. The cost had dropped from about $1.00 per lamp to less than 30¢.
The cables needed to transmit electrical power may seem simple but are actually complex technological artifacts. Cables are designed for many different applications, for example, indoor or outdoor use. This power cable was described by GE engineer William Clark in 1898 as follows: “500,000 [circular mil] cable, 3/32" rubber insulation, braided. [This cable is] for general use in interior wiring."
Invented by Walther Nernst, this incandescent lamp could operate in open air and did not violate Edison’s patents. The housing is sectioned for study of the internal ballast resistance mechanism. The glower consists of six iron rods coated with rare-earth elements. The coating gives off light when heated and protects the rod from oxidation.
Electric power lines have been connecting generating plants to customers since Thomas Edison put lines under the streets of New York City in 1880. Today aluminum lines like these carry electricity hundreds of miles. Hanging these high-voltage lines from towers allows the heat generated by their electrical resistance to dissipate into the air. The expanded area near the center is where the cable connects to an insulator.