Auto Mechanics playlist:
“The physics, science and applications of light.”
Reupload of a previously uploaded film with improved video & sound.
Public domain film from the Library of Congress Prelinger Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).
The earliest headlamps were fuelled by acetylene or oil and were introduced in the late 1880s. Acetylene lamps were popular because the flame was resistant to wind and rain. The first electric headlamps were introduced in 1898 on the Columbia Electric Car from the Electric Vehicle Company of Hartford, Connecticut, and were optional. Two factors limited the widespread use of electric headlamps: the short life of filaments in the harsh automotive environment, and the difficulty of producing dynamos small enough, yet powerful enough to produce sufficient current.
“Prest-O-Lite” acetylene lights were offered by a number of manufacturers as standard equipment for 1904, and Peerless made electric headlamps standard in 1908. A Birmingham firm called Pockley Automobile Electric Lighting Syndicate marketed the world’s first electric car lights as a complete set in 1908, which consisted of headlights, sidelights and tail lights and were powered by an 8 volt battery.
In 1912, Cadillac integrated their vehicle’s Delco electrical ignition and lighting system, creating the modern vehicle electrical system.
“Dipping” (low beam) headlamps were introduced in 1915 by the Guide Lamp Company, but the 1917 Cadillac system allowed the light to be dipped with a lever inside the car rather than requiring the driver to stop and get out. The 1924 Bilux bulb was the first modern unit, having the light for both low (dipped) and high (main) beams of a headlamp emitting from a single bulb. A similar design was introduced in 1925 by Guide Lamp called the “Duplo”. In 1927, the foot-operated dimmer switch or dip switch was introduced and became standard for much of the century. The last vehicle with a foot-operated dimmer switch was the 1991 Ford F-Series. Fog lamps were new for 1938 Cadillacs, and their 1954 “Autronic Eye” system automated the selection of high and low beams.
In 1935 Tatra T77a introduced light with cornering function – the front had three headlamps of which the central unit was linked to the steering, making it possible to turn this lamp with the steering wheel.
The standardised 7-inch (178 mm) round sealed beam headlamp was introduced in 1940, and was soon required for all vehicles sold in the United States. Britain, Australia and other Commonwealth countries, as well as Japan, also made extensive use of 7-inch sealed beams. With some exceptions from Volvo and Saab, this headlamp size format was never widely accepted in continental Europe, leading to different front-end designs for each side of the Atlantic for decades.
The first halogen headlamp for vehicle use was introduced in 1962 by a consortium of European bulb and headlamp makers. Halogen technology increases the efficacy (light output for given power consumption) of an incandescent light bulb and eliminates blackening of the bulb glass with usage. These were prohibited in the U.S., where non-halogen sealed beam lamps were required until 1978. Starting that year, sealed beams became available with halogen bulbs inside. These halogen sealed beams remain available, 25 years after replaceable-bulb headlamps returned to the U.S. in 1983.
High-intensity discharge (HID) systems were introduced in 1991s BMW 7-series. European and Japanese markets began to prefer HID headlamps, with as much as 50% market share in those markets, but they found slow adoption in North America. 1996’s Lincoln Mark VIII was an early American effort at HIDs, and was the only car with DC HIDs…