Probably most people who deal with asphalt know that in the 19th century the major source of asphalt for contractors in the United States was the island of Trinidad in the Caribbean some 2,000 miles south of New York City. There, in the stunted throat of an extinct volcano, a lake of asphalt, bitumen combined with clay, covers about 114 acres. The surface of this unusual lake is strong enough to walk on, permitting workmen with mattock and shovel to dig out chunks, but any heavy object left on the surface will sink out of sight in 48 hours. The remarkable feature of this seemingly bottomless pit of hydrocarbons is that it bubbles up from below to fill in the excavations made by workmen removing chunks from the surface.
By 1900, Trinidad was exporting thousands of tons of raw asphalt to the United States where this remarkable material was fast becoming the favored material for paving city streets. But there were many false starts, and it was literally centuries before asphalt caught on.
The Bible tells us that Noah used bitumen to caulk the Ark. And sometime before 562 B.C. Nebuchadnezzar, the Babylonian king, used it to pave a short section of a ceremonial roadway. Christopher Columbus, on one of his voyages to the New World in the 1490s, was shown the pitch lake of Trinidad by friendly Carib Indians. But Columbus had his mind set on finding gold, so he gave little thought to the potential of the asphalt lake.
A hundred years later another explorer from the Old World, Sir Walter Raleigh, reached Trinidad. When the natives showed him the pitch lake, he promptly recognized the value of the bitumen for caulking his ships. He even went so far as to say the substance was superior to the traditional Norway pine pitch for caulking because it didn’t melt in the sunlight.
Neither the observations of Columbus nor those of Sir Walter Raleigh led to any significant interest in Trinidad Asphalt. Not until nearly 150 years after Sir Walter’s voyage did a visitor recognize the commercial potential of Trinidad asphalt. In 1849, Admiral Thomas Cochrane, the Earl of Dundonald, who commanded the Royal Navy’s West Indian squadron, visited the pitch lake and immediately grasped its significance. Admiral Cochrane was an authentic naval hero and a most unusual individual. He was a man with a lively imagination and boundless energy both of which attributes he displayed by the number of inventions credited to his name.
One of his earliest inventions was a new kind of street lamp which at least one community actually adopted. Most of his inventions had a nautical application. These included an improved and more efficient steam boiler, a rotary steam engine which offered greater efficiency than the conventional reciprocating piston engine, and a ship’s propeller with blades set at an angle to counteract the centrifugal forces of the screw. His rotary steam engine was developed enough to be subjected to a trial in a Royal Navy vessel. Another of his inventions, a method of using air pressure to tunnel under rivers, was subsequently widely adopted by engineers in England and the United States.
At the time the Admiral visited the Trinidad pitch lake, no effort was being made to mine the asphalt for industrial use. Given Cochrane’s lively imagination and inventive turn of mind, he was quick to sense the commercial and military possibilities the great bitumen deposit offered. Access to the bitumen as a source of fuel for steam powered vessels would give the Royal Navy in American waters a marked advantage over potential enemies relying on European coal sources to power their warships. So, he set his sailors to work hacking out quantities of asphalt from the lake and hauling them to the shore.
The admiral’s flagship, HMS Wellesley, named after Lord Wellington, the hero of Waterloo, was an old line-of-battle sailing ship, but his squadron included a steam vessel, HMS Scourge. He ordered the crew of this steam warship to take on board twice the amount of asphalt as she had coal. On the voyage home, he conducted an experiment, using the bitumen as fuel. When the winds faltered and becalmed his flagship, the admiral had Scourge tow the Wellesley until suitable winds returned.
Quite apart from any benefit Trinidad pitch might confer as fuel for the Royal Navy, the admiral envisioned countless commercial applications. Soon after reaching England he filed various patents covering the use of asphalt in numerous applications such as insulation for wiring, sealing water conduit joints and many other waterproofing uses. But his great hope was that asphalt could be used to pave streets in London and other British cities. To demonstrate his notion of asphalt paving, he arranged to have a section of a street in London paved with the material he had brought from Trinidad.
Unfortunately, the experiment ended in failure. The workmen who laid down the pavement had no understanding of this novel material and the resulting surface was so slippery that horses continually fell and injured themselves. The ensuing complaints, not to mention the threat of lawsuits, so discouraged the admiral that he ordered his crew to jettison the Scourge’s remaining cargo of asphalt at sea.
The record doesn’t reveal, but presumably the conservative bureaucrats at the admiralty also showed no interest in bitumen as a source of fuel. However, not everyone was blind to the advantages Cochrane envisioned. Within a dozen years, other men, notably in France, experimenting with this remarkable new material found ways to process it successfully, starting it on its long career as the world’s best paving material.
(Reprinted with permission of National Asphalt Pavement Association from their HMAT magazine, January/February 2005.)