PAST IMPERFECT:Car headlamps have come a long way – from oil to smoke and mirrors, up to present high-tech versions, writes Bob Montgomery
AT THE turn of the 20th century, a solution appeared to all those early motorists who had hitherto fore had to rely on oil lamps to light their way through the darkness. In truth, the flickering oil lamps produced barely enough light to allow for the avoidance of the biggest potholes.
Thus it was with some enthusiasm that motorists embraced the use of acetylene lighting, despite some fears about certain of its limitations which included the possibility of explosions, as well as the requirement for frequent inspections of the carbide-water reaction. Despite these problems, carbide lighting reigned supreme for the next 15-20 years as the universal lighting system on motor cars.
There is a widespread belief among car enthusiasts that early lighting systems were inefficient, but such was not the case with regard to carbide lighting.
When it appeared, it represented a significant step forward in lighting efficiency for motorists and opened up the possibility of driving at night to many who would not have attempted this using oil lamps.
The acetylene/carbide system produced a vivid greenish flame and the problem of dimming was solved by using a hemispherical mirror which could be manually switched through 180 degrees until the flame was obscured. This “dipped” position was used for driving in a built-up area or when following another vehicle.
When the mirror was returned to its position behind the flame, the light was intensified to its maximum.
This mirror system – designed and developed by Zeiss – was incorporated into the earliest electric lighting systems when they were introduced.
Later, as more powerful batteries became available, it was found more practical to incorporate a second, less powerful bulb for “dipping”.
The next major step forward – apart, that is, from the ever-improving battery efficiency – was the adoption of double-filament bulbs around the end of the second decade of the last century.
Early double-filament bulbs were not particularly successful due to a very big disparity between the output of the two filaments.
In addition, legislation in many countries required the incorporation of a side or parking light into the lamp unit.
It was not until this was removed to a separate unit after the second World War that real improvements were made in lighting efficiency.
Interestingly, it was only at this stage that headlights began universally to be built into the front wings of cars as prior to this they were not always supplied with the coachwork and were an ‘after sales’ fitting by the owner.
Since these early developments, lighting systems have evolved in dramatic fashion into the super efficient set-ups available today. Perhaps the biggest single step forward came with iodine vapour lamps, first introduced in the 1960s, which produced dramatic improvements in the amount of light produced – and they didn’t suffer from the “ageing” of previous systems that was a result of the blackening of the bulb and ongoing consumption of the filament.
It’s all a very big step from the flickering light of the earliest oil lamps so familiar to early motorists.