Woodward and Evans Light Bulb

Background

In the first decade of the 19th century, British chemist Sir Humphry Davy developed the arc lamp. This battery-powered device shed light from an arc of electricity bridging two charcoal conductors. Its invention spurred research by British scientists into refining a practical light bulb. The challenge they faced was to produce an electric light with an affordable, long-lasting filament. A filament is a thin strip of conducting material that releases light and heat when connected to an electric current. Early experiments used expensive platinum filaments. By the 1860s, filaments were being made from carbonized paper. These were neither long lasting nor efficient, however. The vacuum in the bulb — created to keep the filament from oxidizing and breaking down in the open air — was inadequate. Electrical sources needed improvement, too.

Woodward and Evans’s Experiments

Medical student Henry Woodward and hotel keeper Mathew Evans were neighbours in Toronto who conducted experiments using a battery and an induction coil. At dusk one winter evening in 1873, they noticed the light created by the spark at the contact post. According to one account, the light was bright enough for Evans to see the time on his watch. “If one could only confine that in a globe of some sort,” Woodward wondered, “what an invention we would have! It would revolutionize the world!”

Woodward and Evans developed a prototype incandescent bulb with a carbon rod filament. It resembled earlier experiments by English scientist Sir Joseph Swan. Their vacuum was stronger than Swan’s, however. It allowed the airtight bulb to keep the nitrogen they had pumped into it. The pair demonstrated their bulb to financiers at the Morrison Brass Foundry on Adelaide Street West in Toronto. “There were four or five of us sitting around a large table,” Evans later recalled. “Woodward closed the switch and gradually we saw the carbon become first red and gradually lighter and lighter in colour until it beamed forth in beautiful light. This was the most exciting moment of my experience.”

Patents

Woodward and Evans’s patent, submitted on 24 July 1874 and approved (#3,738) on 3 August 1874, provided the following description of their light:

A piece of carbon, as hereinbefore mentioned, pure in quality, and of suitable size, proportionate to the size of lamp or vessel to be used, is scraped and shaped until fitted for the purpose. One electrode is then connected with the carbon at the top, and the other electrode is connected with the carbon at the bottom, in the following manner. A small hole is drilled a short distance into each end of the carbon to fit the electrodes, and when necessary they are further secured by surrounding them with a portion of plaster of Paris or other suitable substance. The electrodes not passing through the carbons, nor connecting with each other. It is then enclosed in a globe, or other vessel, either of glass or other suitable material. The air is then extracted from the said globe, or vessel, after it has been hermetically sealed at the ends, and then filled with rarified gas that will not unite chemically with the carbon when hot. Electricity is now supplied and in sufficient quantity, so as to heat the carbon within the vessel to a state of incandescence, the rarified gas previously introduced now becomes luminous, and constitutes the light herein designated as Woodward and Evans’ Electric Light.

Woodward and Evans failed to secure enough investment to cover the high cost of producing the bulbs. They persevered despite being publicly mocked as eccentrics and obsessives. In 1876, Woodward was issued a patent (#181,613) in the United States. The pair’s efforts to draw investment remained fruitless, however. Woodward abandoned the project and sailed to England, while Evans lacked the funds to continue his research.

Thomas Edison’s Light Bulb

Work continued on both sides of the Atlantic Ocean to produce a commercially viable incandescent light bulb. In England, Joseph Swan produced a working light that he patented in Great Britain in 1880. The vacuum tubes he used were inefficient, however, and his thick filaments burned out quickly. Thomas Edison worked in his Menlo Park, New Jersey, laboratory to refine the composition of the bulb. He also bought several existing patents. In 1879, he paid $5,000 for Woodward’s US patent.

By October 1879, Edison had made a bulb that shone for up to 14.5 hours. Further refinements built on the concept of high resistance, allowing heat and light to build in the bulb’s filament instead of the feed wires from the power source. Edison incorporated the bulb into an electrical system of power lines and other equipment. This made the device more practical for everyday use. He also secured funding from wealthy American financiers. His patent was subjected to a lengthy legal battle when the patent office ruled it was based on the work of others. His company also threatened Swan with legal action, until, in 1883, the two inventors teamed up to produce bulbs in Great Britain. Edison’s commercial light bulbs of the 1880s used filaments of carbonized bamboo that could burn for more than 1,000 hours.

Legacy

While their work contributed to the growth of electric lighting, Henry Woodward and Mathew Evans disappeared into history. After their project’s demise, Evans reflected that “the inventor never gets the reward of his labour.” Bulbs continued to use carbon-based filaments until the development of more efficient tungsten filaments in the early 20th century.