Editorial Consultant: Rod Burman

BEEHIVE BULB, 1950's

Beehive bulbs were used as night lights for children as well as for illuminating dark areas. Drawing a very small amount of power, as the illumination comes by excited the internal Neon gas from a high voltage, such as mains electricity. When used with Alternating current both elements (both coil and flat plate) will glow alternately, with Direct current only one element will glow depending on the polarity.

One is operating in the museum.

A1597

WWII DUNGENESS LIGHT HOUSE SPARE LAMP

Removed from the lighthouse during WW2 and held in storage since then.
It was removed to prevent subversive organisations from using the light for signalling in the event of an invasion.

A0194

GEC BARRETTER, 1930's

Barretters are temperature sensitive resistors used for stabilising voltages in wireless receivers, usually powering the heater circuits, of AC/DC receivers.
Acting like a resistor but with constant current characteristics, a current over a particular range can be held constant over a range of varying voltage. A Barretter usually consists of an Iron wire held in Hydrogen filled glass envelope. Also used for many other applications.

A0692

ROBERTSON CARBON FILAMENT BULB, 1920's

Robertson Carbon Filament bulb 80 Volt 8 Candle Power
Within a very few years, the Robertson Lamp had proved itself by far the most successful in the UK marketplace. In spite of this lamp being the most expensive on the market, the factory was producing and selling 4 million lamps per year by 1904. The statistic is significant because at the beginning of 1904 the thermionic valve had not been invented, many of the materials, technologies and processes that would be needed for valve making were already in place by virtue of the effort expended on establishing manufacturing of the electric lamp.

A0695

EDISON CARBON FILAMENT BULB, 1900's

This bulb is an Edison 100 volt 16 candlepower carbon filament.
Contrary to popular belief, Edison didn't "invent" the light bulb, but rather he improved upon a 50-year-old idea. In 1879, he used a lower current of electricity, a small carbonized filament, and an improved vacuum inside the globe, he was then able to produce a reliable, long-lasting source of light. The idea of electric lighting was not new, and a number of people had worked on, and even developed forms of electric lighting. But up to that time, nothing had been developed that was remotely practical for home use. After about one and a half years of work, he produced an incandescent lamp with a filament of carbonized sewing thread that burned for thirteen and a half hours.

A1275

CARBON FILAMENT LIGHT BULB, 1900's

There are no markings on this bulb.
Joseph Wilson Swan (1828-1914) was a British physicist and chemist. In 1850, he began working with carbonized paper filaments in an evacuated glass bulb. By 1860 he was able to demonstrate a working device but the lack of a good vacuum and an adequate supply of electricity resulted in a short lifetime for the bulb and an inefficient source of light. By the mid-1870s better pumps became available, and Swan returned to his experiments.
Thomas Edison (1847-1931) began serious research into developing a practical incandescent lamp in 1878. Edison filed his first patent application for "Improvement In Electric Lights" on October 14, 1878
After many experiments with platinum and other metal filaments, Edison returned to a carbon filament. The first successful test was on October 22, 1879, and lasted 13.5 hours. Edison continued to improve this design and by Nov 4, 1879, filed for a U.S. patent for an electric lamp using "a carbon filament or strip coiled and connected ... to platina contact wires."
Although the patent described several ways of creating the carbon filament including using "cotton and linen thread, wood splints, papers coiled in various ways," it was not until several months after the patent was granted that Edison and his team discovered that a carbonized bamboo filament could last over 1200 hours.
On December 13, 1904, Hungarian Sondor Just and Croatian Franjo Hanaman were granted a Hungarian patent for a tungsten filament lamp in Budapest, which lasted longer and gave a brighter light than the carbon filament.
Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1905, so this type is often called Tungsram-bulbs in many European countries.

A1311

EARLY LIGHT BULB, 1900's

Probably used as a test unit for low voltages in a workshop or laboratory

A0852

SIEMENS CARBON FILAMENT 220 VOLT LIGHT BULB, 1900's

Early light bulb made by Siemens with carbon filament.
Like Robertson many companies started producing carbon filament lamps once the Edison Patent had expired.
For more information see Item A0695.

A0696

DUAL FILAMENT LIGHT BULB 115 VOLT, 1920

Unique Lamp with two Filaments and three connections on the Bayonet base, turning a ring around this moved the locating pins to the other connection. If the first filament blows, simply turn to the other one.

A1274

ROYAL EDISWAN TUNGSTEN FILAMENT 130 VOLT BULB, 1930's

Bulb used in Trolley Buses and Trains up to and during the 1930's.

A0698

10,000 WATT LIGHT BULB, 1950's

Large 10,000 Watt lamp.
Uses uncertain, probably a stage lamp, or small Lighthouse.
A similar bulb can be seen in the opening credits to the TV show Time Watch.

A0691