Sunday, 18 September 2022

Locomotive Steam Engine

James Watt’s steam engine was a big improvement over the Newcomen steam engine. The timing of the James Watt’s improvements were impeccable, coming along when the Cotton Revolution was well under way. Improvements in metallurgy were critical. Watt’s business partnership was with Boulton excellent.

The invention of crank shafts and sun-and-planet gears, which converted the linear motion of the steam driven pistons into rotary motions which powered wheels, textile looms, and grain mills, made the steam engine the prime mover of the Industrial Revolution.

But the next stage of evolution, the emergence of the locomotive steam engine, took nearly fifty years after Watt’s improvements and innovations. James Watt himself planned a road based locomotive, and his assistant Murdoch designed a model, but they never built one. Three people played key roles in the emergence of the locomotive steam engine and the railways: Richard Trevithick; George Stephenson and Robert Stephenson.

Richard Trevithick 
Pic: Wikipedia

Richard Trevithick

Richard Trevithick grew up in Cornwall, full of coal mines, the district of England where most of James Watt engines were installed in the first few years. Unlike James Watt, he had no fear of high pressure steam.

He conceived the boldest, most imaginative changes to the steam engine. But he had to wait until 1800 when James Watt’s patent, extended by Parliament, expired. Boulton and Watt’s phenomenal success, fame, and global recognition, especially among the aristocrats of England, worked against Trevithick, a commoner from lower classes. But his advantage was that neither science nor technology respects reputations; only society does.

First Trevithick realized that the condenser itself was not necessary. This alone was quite revolutionary. The right amount of steam pressure is sufficient to run the engine, if it was higher than atmospheric pressure. In fact, he was working for the DingDong mine, and trying to help them avoid paying royalties to Boulton & Watt – when he had this epiphany. He built a engine running at 30 psi, three times the pressure in Watt’s engines. The higher pressure meant a smaller, lighter engine, with a power-to-weight ratio sufficient to power its own locomotion.

Second, he put the furnace inside the boiler. Just the sheer audacity of this design is mind-boggling – but taken for granted once it was accomplished. Tubes ran inside the boiler, heating all the water around them, rather than just heating a vessel from the bottom, as is still mostly common in cooking. He made the boiler horizontal rather than vertical which suits this model of heating so well. Excess steam was let out with a blast pipe, since the condenser was eliminated. A safety valve was added.

Another major design change was that the piston and its cylinder were tilted, at a 45 degree angle. The tilted operated a set of wheels via a crankshaft. Basically, the whole engine was a boiler fitted on to wheel-based chassis.

These seem to be the most radical alteration in design of any major mechanical device, until the advent of turbines nearly a century later. Several things helped Trevithick : first a much better understanding of heat, steam, flow etc. Second, there were incremental improvements in metallurgy, which allowed for stronger cast iron cylinders which could withstand higher steam pressure without exploding.

Puffing Devil
Pic: Industrial revelations - Youtube

Trevithick built a steam locomotive for the road, in 1801, called the Puffing Devil, which featured all these innovations. It had a successful road test, with a few people. But it was hard to steer, fell into a gully, and left unattended, the furnace still boiling water, exploded when it all the water boiled off. He later built another vehicle for the road called London Carriage, but it also had a lever-steering, and no one wanted to buy it.

He patented this high pressure steam engine in 1802. He sold it as a stationary engine, powering a water pump and operated at 145 pounds per square inch (PSI) compared to around 10psi for Watt’s engines. One of these engines exploded, killing four people, and James Watt called for hanging Trevithick for killing them. But it was shown that it was operator error, not a design problem. Trevithick added a second safety valve, which would open and quench the furnace with water, shutting it down, if the pressure exceeded danger levels.

In 1802,  Trevithick also built a steam locomotive that ran on rails, called the Penny Darren. It successfully carried cargo and passenger wagons for 15 km, at a slow speed of about 4kmph. Historians consider this the first steam locomotive train. But the engine was too heavy for the cast iron rails, which broke.

Trevithick's Penny Darren steam locomotive
Pic: Industrial Revelations - Youtube

Trevithick spent the rest of his life building stationary engines, and several other experimental devices, but none of them brought him the commercial success that Newcomen and Watt got from their engines. He spent some years building engines for mining in South America, but returned to England when war broke out. He died almost a pauper, and was only recognized for his contributions and honored after his death.

George Stephenson

Where Trevithick failed, George Stephenson, ten years his junior, a coal worker and self-taught mechanical engineer, succeeded, barely a few years later.  Illiterate until the age of 18, he attended night school to learn to read and write, to add to all his practical knowledge. Wagons running on wooden and cast-iron rails, usually pulled by horses, had become popular over several years. Inspired by Trevithick several others built high pressure steam locomotive, to replace horses, including Stephenson, in 1814. He built several locomotives, all of which eventually damaged the rails by their weight. Stephenson came up with some innovations like steam springs, and using more wheels, to distribute weight. In the meanwhile, iron smiths had developed wrought iron, which had lower carbon content than cast iron, was tougher and more malleable.

In 1821, Stephenson was hired to build the 40km Stockton-Darlington railway line, to carry horse drawn wagons. He convinced the director, Edward Pease, to use a steam locomotive instead, running on wrought iron rails. The Stephenson engine was a slightly improved version of the Trevithick engine, featuring horizontal boiler, internal furnace, water tubes, tilted pistons and blast tube.

His son Robert Stephenson, built an engine called Locomotion, which hauled a coal wagons for 14 km in 2 hours. The successful run inspired another the commissioning of a railway line between the much larger industrial city of Manchester, hub of the cotton industry, and the harbour town of Liverpool, a distance of 97km. The biggest challenge now was building a railway line over varied terrain including marshes and peat bogs, and George Stephenson took on this challenge.

Robert Stephenson's "Rocket"
Pic: Wikipedia

The directors of the LMR railway line arranged a competition among five different locomotive engines, in 1829, one of which “Rocket”,  was built by Robert Stephenson, son of George. It was the only one that completed the run, so it won. It became the model for all future railway locomotive engines. This success, launched an era of building railway lines, carrying both cargo and passengers, first across England, then in several European countries, launching a total revolution in the field of transportation.

The Stephensons found the financial success and fame, that sadly eluded Trevithick whose innovations were the basis of the railway revolution.

Economic and Social Impact

Railway lines were built all across Europe, then the USA, and in India in the next few decades. The cost of transporting goods dropped precipitously. The time for travel across land also dramatically reduced from days to hours. In parallel, steam powered boats, then ships, made ocean voyages cheaper, safer and more predictable; and cost of shipping goods across the world also dropped spectacularly. The great benefits in manufacturing, powered by stationary steam engines, now could reach all corners of the world, thanks to locomotive steam engines.

It also had downsides. Vast numbers of artisanal workers, especially weavers in Europe and later India, lost their livelihoods or became poorer, as the couldn’t compete with loom produced textiles. But the number of manufactured goods increased dramatically, making necessities out of luxuries.

The political consequence was Britain’s ascent as an unprecedented global industrial, technological, military, economic and hence political, superpower. The nineteenth century was truly the century of steam power, which continued well into the twentieth century, even decades after the invention of electrical, deisel and oil powered engines, and later turbines.



Industrial Revelations : Youtube series

ThoughtCo website

Related Links

James Watt's Steam Engine

Charles Parsons and Steam turbines

Essays on Inventors and Discoverers

Monday, 5 September 2022

James Watt and the Steam Engine

We have heard the fabulous story that young James Watt watched a water boil in a tea kettle, which rattled the kettle’s lid and struck James by the power of steam. This childhood experience, the story goes, inspired him to invent the steam engine as an adult. It is indeed a marvelous fable, ranking with Newton’s apple.

But why didn’t a Chinese James Watt invent the same steam engine, long before the English one? After all the Chinese have been boiling tea for a thousand years before England. Why not a Tamil boy or girl watching idli being steamed? Same water. Or someone in Sumeria or Egypt?


It turns out, even James Watt was not the first Englishman to work on a steam engine. The Royal Society of England records a Frenchman Denis Papin, who claimed to have run a steam powered boat on a French river, with recommendations from Gregory Leibniz and Christian Huygens. Some drawings of Papin survive, but nothing else. Some historians say that Isaac Newton, a fierce rival of Leibniz was then President of the Society, and ignored Papin because of his Leibniz connection. Curiously, neither Newton nor most scientists of the society, showed much interest in either Papin’s engine or even about heat as worthy of scientific study.

But in 1698, a patent was filed by an Englishman Thomas Savery, for a “fire-engine” – that is, a boiler of water heated by a coal-fired furnace. The steam produced pushed a metal piston up. This piston was attached to a lever, at whose other arm was suspended a bucket which was lowered into a coal mine. Coal mines often filled up with ground water, which prevented mining. When the bucket filled with water from the coal, the boiler was cooled by splashing cold water on it. This cooled the boiler and the steam, which condensed and the steam pressure, which had driven up the piston, fell. Atmospheric pressure then lowered the piston, and the connected lever pulled up the bucket full of water. Today we call this a pump – but since it was powered by heating water, the popular name was fire engine. Several Savery engines sold for around 150 to 200 pounds. This was the first effective steam engine : but since the actual work of lifting the water was done by atmospheric pressure rather than the steam, historians call Savery’s engine an “atmospheric engine.”

Newcomen's Steam engine:
Pic from: Michael de Greasley's Youtube video

Savery had a fourteen year patent, which was extended to 35 years, until 1733. A generation later, in 1712, Thomas Newcomen, another Englishman, made some improvements to the Savery engine, paying a license fee to Savery’s heirs. His Newcomen engine, was also an atmospheric engine, but it was safer, could stand higher heat and steam pressure, and could pump up water from 150 feet rather than the thirty feet of Savery’s engine. So it was popular among coal and other miners, who paid a royalty of about 450 pounds a year to operate a Newcomen engine. 

Mathematical Instruments

James Watt, was born far north of the British island, in Scotland, in 1735 (after Savery’s patent had expired, and Newcomen engines became popular). He went to school, where he was taught mathematics and astronomy, which he loved more than Greek and Latin, which were also part of his education. When he turned eighteen, Watt traveled to London, to learn some skills as an apprentice. Carnegie says that it was a twelve day travel by walk or horse carriage; quite hazardous; and the whole village met in church to pray for such travelers’ welfare.

Watt joined John Morgan of Cornhill road, a maker of mathematical instruments. These were navigational instruments like the compass, the telescope, the quadrant, the geared watch; mercantile instruments like brass scales, rulers; surveying instruments like theodolites, etc. Watt was described as  “having a fortune at his fingers’ ends”; that is mechanically very talented; and he was a quick learner. After a couple of years, he returned to Glasgow to set up a  shop selling such devices. But he wasn’t very successful. He expanded to repairing musical instruments like fiddles and pianos, and fishing equipment and surveying tools.

Early experiments at Glasgow

He had made friends with some academics at the University of Glasgow and was allowed to perform some experiments there. The university had a model version of a Newcomen engine, which had broken down, and even Watt’s efforts couldn't fix it. The model was sent to London for repair, but a curious Watt built a similar model himself, using a vial as a boiler and hollow canes as tubes. He observed that the engine wasted a lot of heat, alternately cooling and heating the cylinder. Experimenting a little more, he discovered Latent Heat.

Latent heat is the property of water, whereby when it reaches its boiling point, it doesn’t immediately turn to steam, but continues to absorb heat without any sensible (measurable) change in temperature. After absorbing this heat for a while some of the water turns into steam. The heated steam has much more thermal energy than water at the same temperature (five times, as Watt found out).

Excited, he met Professor Joseph Black of the university, and explained what he had discovered. An amused Black, showed Watt that he had discovered the same phenomenon a few years earlier. They gained a mutual respect for each other.

External Condenser

Believing Watt could improve the Newcomen engine, a local businessmen, John Roebuck formed a partnership, investing a thousand pounds for Watt’s research. The understanding was that, when Watt finally made a better engine, Roebuck would get two thirds  of the revenue as the financier.

Watt’s first great insight was about the inefficiency of alternatively heating and cooling the cylinder, to get mechanical work out of it. In 1769, he added an external condenser to the engine, which received the piped off excess steam. This vastly increased the efficiency of the engine. Several mine owners bought this engine from Watt.

But, then Roebuck went bankrupt. And Watt stopped working further on improvements to the engine.

An Era of Canals

Watt spent several years working as a surveyor, putting his mathematical skills to use. He surveyed several canals, designed bridges, and docks and piers. He surveyed the Monkland, Clyde, Forth, Caledonian and Perth canals, receiving about 400 for the last of these. He designed a bridge over the river Clyde for which he was paid 37 pounds.

Horse drawn Boats

It was the age of canals in England. Catching up to Europe, India, China and other countries which had developed intricate networks of canals over the centuries, England built several new canals for transport. One of the wettest countries in the world, it was blessed with several perennial rivers and streams. Connecting these with canals was quite profitable for landowners, especially owners of coal and iron mines. Transporting by water was far cheaper than transporting by muddy roads over uneven terrain. Horses walking alongside the canals could pull more loads on water than on land.

Matthew Boulton

Boulton was a maker of “toys” – by which was meant decorative cups and jars, plated jewellery, silver plates, candlesticks, buttons, buckles, mirrors – things sold by “fancy stores” in every street corner in India today. He had a manufactory at Soho, near Birmingham, an area rich in coal, which had developed an ironwork industry. The factory was mainly water powered.

In his times, France was considered superior to England at manufacturing these “toys”. Often, Boulton shipped good from his factory across the English channel and then had them return, pretending the goods were imported from France. This was an effective business tactic. He soon drew wealthy and reputable customers, including the best advertisers possible – the English royal family. When princes George (later king) and Edward bought swords from Boulton, his reputation, and business, soared. He even attracted the attention of Princess Catherine of Russia, who declared his products superior to those of France.

Reduced summer time water flows in the streams powering his mills, convinced Boulton to buy a Watt engine to pump water into a lake to supply his factory. After seeing Watt’s external condenser engine, Boulton realized not only could it renew his water supply, a better steam engine may replace it and power his factory. Cashing in on a debt that Roebuck owed him, Boulton took over from Roebuck as a business partner for Watt and persuaded him to move to Birmingham and work on improving the engine.

James Watt was lucky to get such a good and influential friend. He had great faith in Watt as an inventor and spoke in praise of him to whomever listened. Catherine of Russia listened, and agreed, and offered Watt five thousand pounds to move to Russia and continue his investigations. It took an alarmed Boulton all his persuasive powers to keep Watt in England.

Industrial Success

One major problem was the reliability of cylinder to operate under the higher pressure and heat of steam. An iron-master John Wilkinson, invented a boring machine, with which he made stronger cannons. Boulton introduced him to Watt, who began using Wilkinson’s cylinders for his steam engine. Wilkinson was not only a supplier, he was also one of the first customers of Watt’s engines, which he used for blowing machines, forge hammers and other metal works.

The first Watt engines were popular among mine owners, who cancelled orders for Newcomen engines. These engines were not manufactured, but assembled on location from assembled parts constructed on site under Watt’s personal supervision. Most of the parts and even the tools were handcrafted by smiths. Alcoholism, the lack of engineers, absenteeism were major problems for their business. Some others began copying the design without paying Watt a patent fee.

Boulton and Watt offered a business model, based on the far superior efficiency of the Watt engine over the Newcomen engine. Most of the money was saved on coal used to power the engine. The mine owners were charged one-third of the estimated savings on coal – for example, if a Watt engine used 400 tonnes of coal compared to an earlier Newcomen engine which used 1000 tonnes, the customers had to pay the cost of 200 tonnes (one third of the cost of 600 tonnes of coal they saved). This led to a lot of bargaining disputes and negotiations, all of which Watt was personally averse to. Fortunately, Boulton’s excellent business skills came into play.

Boulton got the patent extended for twenty years, from 1775 to 1800, by an act of Parliament. This ensured no other company could make or sell a steam engine with an external condenser. So inefficient Newcomen engines continued to be sold. This also prevented innovations and experiments with high pressure engines, which Watt detested as potentially deadly.

Boulton realized that the steam engine had a limited market as  a pump, with only a linear action; if the pistons linear movement could be converted to a rotary motion, whole new industries would buy the engine. A competitor, Pickard, had developed a crank-shaft to do just that, but wanted to cross-license it with the external condenser. Watt refused. He instead invented a sun-and-planet gear, an alternative mechanism that turned linear into rotary motion, in 1781. He sold an engine with this rotary mechanism to Whitbread’s brewery, which replaced horses with Watt’s engines to grind corn. Boulton proposed that brewers pay for one-third of the horses that breweries replaced – if the Watt engine replaced eighteen horses, they received annual fees equivalent to the cost of maintaining six horses. This was also the beginning of the practice of rating engine power in number of horses : or horsepower.


Meanwhile Watt worked on other improvements. In 1781, he also developed a double acting engine, where the steam operated on both ends of the cylinder. In 1782, he developed a compound engine, where two engines combined their power.

He also developed  a steam pressure indicator, which measured and showed the pressure of the active steam, making the operation much safer. An ingenious invention, in 1788 was the centrifugal governor, (originally invented by Huygens), which regulated the rate of steam and rotary action, so that it would neither slow down nor speed up much, but maintain a somewhat constant speed. A steam throttle was useful in actually controlling the amount of steam flowing, and controlling the speed of the rotary engine.

Sun and Planet gear
Pic: Wikipedia

With these significant improvements, other industries also bought the Watt engine. The textile industry which had mechanised looms; the metal forging industry; and mills. Boulton himself employed them later in minting coins. Competitors and patent infringements and fighting over dues were a constant problem. Boulton and Watt lost a lot of potential revenue, but eventually became rich and reputed men, because of their machine.

Prime Mover

The steam engine is a prime mover, which replaced human, animal and water power in a vast number of industries, with. It changed the world in a way that perhaps no other invention before or after has done. The stationary atmospheric engine became a stationary steam engine, slowly expanding into new industries. Then it evolved into a more compact engine, capable of moving itself – a locomotive engine. Finally steam power was adapted to operate turbines.

It was quite gradual; it evolved over two centuries, before diesel petrol and electric engines began to replace steam engines as major prime movers in several industries.

Boulton conscious of its significance and impact, declared: “I sell, sir, what all men desire: power.”

James Watt, inventor extraordinary

Watt was not just an practical mechanic and industrial inventor; he had extraordinary scientific skills as witnessed by his independent discovery of Latent Heat. Humphrey Davy said that Watt “was distinguished as a natural philosopher and chemist; his inventions demonstrate his profound knowledge of those sciences, and that peculiar characteristic of genius, the union of them for practical application."      

Watt invented a copying machine which soaked an original document or drawing in a chemical and could transfer it to another sheet of paper. He didn’t sell many, but some of them were in use for over a hundred years. He improved the gas lamp; invented an unfinished arithmetical machine; and even built a sculpture copying machine.

Carnegie says Watt, continuing on extraordinary discoveries of Joseph Priestley and Antoine Lavoisier, discovered that water was a compound of flammable air and dephlogisiticated air – independently also discovered by Cavendish. But his name is strongly associated with the steam engine, all other discoveries pale in comparison.

Lunar Society

Boulton was not only a business partner for Watt. He was a personal friend and intellectual compatriot. When Watt lost his first wife, and contemplated marrying another lady, her family objected. Boulton wrote a recommendation letter to Watt’s prospective father-in-law lauding his friend’s virtues.

Boulton had met the ingenious American scientist Benjamin Franklin, the Scottish philosopher and economist Adam Smith, a medical doctor Erasmus Darwin (grandfather of Charles), the chemist and clergyman Joseph Priestley and businessman and potter Josiah Wedgwood. He brought them all together at his Birmingham mansion, on full moon nights, discussing science, inventions and discoveries. They called themselves the Lunar Society. They have been called the Founding Fathers of the Industrial Revolution.

Watt eventually died in 1819, a few years after Boulton. Neither of them saw the emergence of the railways, though Watt apparently once journeyed on a paddleboat powered by steam engine. The British magazine “Chemist” paid him a fitting tribute:

“Different from other public benefactors by never having made or pretended to make it his goal to benefit the public. This unpretending man conferred more benefit to the world, than all those who for centuries made it their special business to look after public welfare.”

There are statues to Watt in London, Manchester and Birmingham. The watt was adopted as a unit of power, in 1889, by the British Association for the advancement of Science. The Bank of England issued a ₤50 currency note with images of Watt and Boulton in 2009.


1.       James Watt: A Biography, by Andew Carnegie

2.       Creating the Twentieth Century, by Vaclav Smil

3.       Industrial Revelations : Youtube series

4.       The Lunar Society, by Jenny Uglow

5.       Wikipedia

6.       Other videos, internet

Related Links

James Watt's Steam Engine - my lecture at Varahamihira Science Forum

Charles Parsons - Inventor of Steam Turbines

Inventors and Discoverers - my blogs


Tuesday, 16 August 2022

Thomas Edison : The Wizard of Menlo Park

Thomas Edison’s name is synonymous with electric light, electricity, nay, even invention itself. But what is the actual story of the invention of the light bulb? Why didn’t Faraday or Maxwell or some other Alessandro Volta invent the light bulb? How did a self-educated school dropout succeed where more brilliant men didn’t – and how did he invent it?

Yes, Edison invented the light bulb. But more than twenty others had different patents on the electric light before Edison, over the preceding eighty years. Do we know their names? Also, we know he had a thousand patents, but can you name any of them?

Edison also designed, built and sold electric cars and even trains. We never hear of these! Why? Because they failed in the long term, though they were popular for several years. Petrol cars and diesel trains were far more efficient and economic. Think about this – Edison’s “failures” were more fantastic than most inventors’ successes.

Young Edison learnt, not from school, but from practical experience. (Sometimes too practical: he once tried to hatch eggs by sitting on them). He was forced to drop out of school, as a dullard. But he was incredibly curious and relentlessly enterprising. In his teens, chemistry fascinated him, and he stocked many of them in a home lab. He sold newspapers on trains, to earn a living, and even published a newspaper : he was never just a tinkerer, he was a businessman, who tried to sell his inventions.

Edison's phonograph

Edison’s fascination with electricity started as an apprentice in telegraphy. He saved the life a child on the rail tracks, and a grateful stationmaster taught him telegraphy. Telegraphers were in constant demand, especially by the railways. Insatiably curious, a relentless tinkerer, he taught himself how telegraphy and electricity worked. For nearly fifteen years he made several inventions that improved telegraphy. Among these were a dupleix and quadripleix devices, which could send two and four messages over the same wire simultaneously. 

Some experiments cost him dearly – he once spilt battery acid which destroyed his manager’s desk and carpet; he was fired. His early life was full of adventures; once carrying a load of books at midnight, a policeman fired bullets, mistaking Edison for a burglar! “You’re lucky I’m a bad shot,” the policeman commiserated. 

Edison traveled the southern US, after America’s Civil War, and almost sailed to Brazil, abandoning America. Would a Brazilian Edison have been an equally famous inventor? Eventually, he ended up working for Western Union, moving from Louisville to Cincinnati to Boston. He bought Faraday’s books on electricity. “Faraday was a Master Experimenter,” Edison said in admiration. “His explanations were simple. He used no mathematics. I must have tried every experiment in those books.” In Boston, he published papers on his inventions in a journal called The Telegrapher. Then he quit his job to become a partner in some companies, and to spend more time inventing.

 His first major success was a “Universal ticker”, which he hoped to sell to General Lefferts, president of Gold & Stock Telegraph Co, New York. Edison expected to sell for $5000. When Lefferts offered $40,000 he nearly fainted! But he accepted the money, and with it, started his famous Menlo Park laboratory.


The Menlo Park laboratory

In 1876, Edison set up a research laboratory at Menlo Park, with several assistants to help him explore new inventions. In June, Alexander Graham Bell filed a patent for the telephone and revolutionized communication. Edison spent the next year making experimenting with various components of the telephone. He first added a battery to it, to improve its performance. In January 1887, he invented a transmitter in which carbon pressure changed the resistance. In the following months, he developed a electromotograph receiver, a telephone message recorder, a handheld telephone and an induction coil circuit. Companies in Canada, England and USA showed interest in Edison’s telephones. Western Union established the American Speaking Telephone Company, whose customers were supplied the Edison designed telephones.

At the age of 30, in 1877 he invented the phonograph, based on a recording device he had designed for the telegraph. A machine that could record sound, as needle marks on a metal cylinder, and replay it seemed simply magical and he earned the moniker Wizard of Menlo Park. But the phonograph did not succeed commercially for several years. It had certain limitations : only one cylinder could be recorded at a time; there were no technologies to copy a recording; the electronic amplifier wouldn’t be invented for another twenty years.

After seeing a demonstration of an incandescent electric light bulb, Edison decalred he would make a cheap and long lasting electric lightbulb. He bought a patent from Canadians Woodward and Evans. He hired more scientists and engineers and organized them to work collaboratively at Menlo Park, primarily for electric light. But some of them also worked on telephones, phonographs, mining devices etc. His laboratory was equipped with a tremendous variety of resources mechanical, electrical, chemical and organic.

Remember, giants of science like Alessandro Volta, Benjamin Franklin, Michael Faraday, Thomas Henry, Samuel Morse etc had invented many electrical devices before Edison. Ohm, Ampere, Maxwell and others had researched or explained its science. Telegraphy, electro-magnets for lifting heavy loads, arc lights were popular industrial applications.

Hiram Maxim, inventor of the machine gun and Joseph Swan of England also developed incandescent lights. What did Edison do that these men didn’t?

Edison’s rigor, method and scale, set him apart. He set himself a target of making a long lasting electric bulb. Edison not only set up his lab with resources and people, he scattered notebooks for everyone. An enormous amount of information was discovered and shared among the researchers. 

There was a choice before Edison: he could have improved the arc lamp, or the incandescent lamp. When electricity passes through a metal wire, it gets hot. Some metals glow from the heat – this is called incandescence. Edison chose incandescence. He bought a patent for an incandescent light bulb from two Canadians, Henry Woodward and Matthew Evans.

Early experiments with platinum showed the filament melted at lower temperatures, because of oxidation. So Edison decided to vacuum air out of the bulbs, to prevent oxidiation. Experiments with two existing vaccum pumps, the Geissler pump and the Sprengel pump showed promise. He hired chemists, especially Ludwig Boehm, to device an improved vaccum pump.

He hunted worldwide for nearly forty thousand materials including jute from India and silk and bamboo from China, for his filament. In October 1879, they discovered that carbon-coated cotton thread lasted really long. A few months later, they found out that bamboo worked ever better.

Edison personally designed both the screw base and the socket that most manufacturers used for a century!

Some historians consider the Research Laboratory his greatest invention! Today, there is no major university or company in the world, without a research lab. Governments have started organizations, departments, companies etc to fund and research science and technology, in a systematic method, undreamed of before Edison’s success.

Edison's Insights 

While other inventors focused on low resistance, Edison focused on high resistance. This seems obvious on hindsight, but none of the others – Hiram Maxim, Westinghouse, Joseph Swan, Warren de la Rue, Alexander Lodygin, etc seem to have stumbled upon it. Which is suprising because electric power is proportional to resistance but also to the square of the current. A high natural resistance, meant low current would be good enough to heat the filament and make it glow.

These stem fro Ohms’ Law V= IR

and the equation for power W = VI

which meant, W = I*I*R,

where R is the resistance, I is the current and V is the voltage.

Also, as per Vaclav Smil, alone among other inventors, Edison understood that these lights must operate in parallel circuits than in series circuits. This way the voltage could be stable and each light bulb could be turned on or off with a switch, which is not possible with serial lights. The entire electrical system is designed on this principle.

His lab designed switches, fuses and meters. Edison designed an electro-chemical meter, with metal electrodes in acid. Power consumption was measured by the weight of the zinc deposited on the electrodes. The electro-magnetic meters based on a revolving wheel and meter, were invented later by someone else.

A Complete System

While others were trying to invent a better light bulb, Edison planned and designed a complete electrical system. For small units, acid based batteries, following the designs of Alessandro Volta and Humphrey Davy might have sufficed. But for lighting up streets, they were inadequate. Only steam engine powered dynamos could light up companies, factories, towns and cities.

He bought and tested dynamos designed by Zenobe-Theophile Gramme and Siemens, of Germany, then improved their performance. 

The first power generator station was set up in Pearl Street, in New York. It generated 3.4 MW and served ten thousand light bulbs. Pearl Street began with losses, but produced profits of $35,000 in 1884, five years later. Unfortunately, it was destroyed in a fire accident in 1885. By 1891, 1300 power plants like Pearl Street produced electricity and powered homes and businesses in the USA alone.

Edison thought not just like an inventor, who wanted to make something new, but as businessman, who wanted to lower costs for both his company and customers. His electrical system had to be cheaper, safer and more convenient than the gas lights and oil lamps of the day.

Notebooks and bulb designs


Bulb holder designs

Business Acumen

He founded several companies over the next few years:

·         1878 Edison Electric Light Co  -  Invent Bulb

·         1880 Edison Illuminating Co  - Power station

·         1880 Edison Lamp Co  - Manufacture Bulbs

·         1881 Edison Machine Works – Manufacture Generators

·         1881 Edison Tube Works – Underground wires and pipes

·         1884 Edison Company for Isolated Lighting  - private generators for companies


Investors included admirers of his telegraph and phonograph; the general public via the stock market; and later, the very rich American banker JP Morgan. 

He also established collaborative companies in other countries, most famously with Joseph Swan in Britain (who also invented a working electric bulb, but perhaps not the entire electrical system).


He also had a flair for promotion and marketing. When he finally made a long burning light-bulb, he invited journalists to Menlo Park, on December 31, 1979 and dazzled them, by lighting not only the lab and the house but the entire street with electric lamps ! The Wizard who had made a machine produce human sound, had now turned night into day. 

Special trains were run for the general public, who wanted to visit Menlo Park and see this new miracle.

Edison also invited artists and smiths to design electroliers, to hold electric bulbs, similar to chandeliers which held candles. He set up showrooms where potential customers could see the bulbs in person. He hired artist to portray living rooms with electric bulbs, as tastefully as aesthetic as the flame based lighting, to which the rich and fashionable classes were accustomed.

A chance opportunity came along when the owner of the ship SS Columbia, wanted to install Edison’ lights on the ship. Edison obliged. The ship sailed from New York, down the US east coast, along Mexico and South America, and back up along the coast of the Pacific ocean, ending up in San Francisco, California. It ended up publicising Edison’s invention along the coastal cities of the two American continents, in a way unmatched by newspapers.

Solving other problems

There were engineering and cost problems – mainly of transmission and distribution losses. Edison designed a distribution system, which was both electrically efficient and used far less copper. It saved two thirds of the electricity in copper losses (power wasted by the resistance of transmission wires). Edison’s patented feeder circuit system, based on a three wire system, where two outer wires carried current, and one inner wire was neutral and served as common to both circuits, was a product of his ingenuity. When asked why no one else came up with this brilliant design, the great genius Lord Kelvin himself remarked,  “Because none of us is Edison.”

Edison feeder system

Not only did Edison come up with this design, he insisted that all the wires be insulated and buried underground to avoid electrocution of human beings. Uninsulated telegraph and telephone wires crisscrossed the sky above the streets of major cities, and were a deadly hazard to pedestrians and repairmen alike. Few historians seem to mention or even realized Edison’s great regard for human life and safety.

Electric wires on a New York street

But things did not always go well. There were patent battles fought in courts for a decade over the light-bulb. His Edison Electric went into partnership with Swan in the UK and with Thompson-Houston company in the US. The latter company became General Electric, the largest company in the world for most of the twentieth century.

Edison vs Tesla

The Serbian genius Nikola Tesla, who first joined Edison’s company in France, later joined Edison in the USA. Tesla tried to persuade Edison to abandon Direct Current for Alternating Current, but Edison could not be persuaded. Fundamentally, he seemed to have feared the deadly power of Alternating Current, which electrocuted people; he could not see the efficiencies of generating power at a distance and the efficiencies that came with stepping up and stepping down voltage. Tesla joined Westinghouse and implemented AC there. Their rivalry was so fierce, the narrative goes, that neither would accept a Nobel prize if the other was awarded. But stories of Edison electrocuting elephants and cheating Nikola Tesla seem to be popular urban legends, spread by a legion of Tesla fanatics.

Westinghouse’s eventual economic success later convinced Edison of AC’s virtues. But it was too late and came at a great cost. JP Morgan was frustrated with Edison’s stubborn refusal to accept AC, and the subsequent lower profits of the electricity business. Meanwhile Edison was selling his shares of the companies he founded, to finance new research and inventions. Edison wanted to venture into other areas of invention, like industrial mining, making cement, making electric cars and trains, turning his phonograph into a nickolodeon, inventing a movie camera etc. JP Morgan eventually bought enough shares to throw Edison out of the Edison General Electric company, and dropped Edison’s name from it.

Edison never rested on his success. He spent the rest of his life a workaholic, running factories and labs, twelve hours a day. He hired Ambrose Fleming to investigate what was called the Edison effect; this would later result in the invention of the vacuum tube diode, and the foundation of electronics. Fleming is now considered the Father of Electronics.

Later, Edison hired Henry Ford, who rose quickly through the ranks and became Chief Engineer. But Henry Ford had dreams of building a petrol-based car, while Edison tried to make a better electric car. Ford finally quit, and his petrol car triumphed over Edison’s electric car. But Edison and Ford remained lifelong friends.

In 1983, the US Government declared February 11, Edison’s birthday, as Inventor’s day. 

NOTE A shorter version of this essay was originally published, as part of a series on scientists, in the New Indian Express. The photos are from the Edison exhibit, in the American History Museum, part of the Smithsonian, Washington DC, USA

This longer version was prepared for a course I teach called "Inventions and Discoveries", at Saveetha Engineering College, Madras.


1.      Edison gallery – Museum of American History, Washington DC, USA

2.      Edison – His Life and Inventions by FL Dyer and TC Martin

3.      Creating the 21st century by Vaclav Smil

4.      Thomas Edison - Wikipedia

       The Invention of Everything - Matt Ridley

Related Essays

Watt and Edison - crucial breakthroughs

Inventors and Discoverers

Edison vs Tesla - a video by Kathy Joseph

Saturday, 23 July 2022

Undiscovered Vishnu temple in Mamallapuram

Mamallapuram has many interesting monuments. Most were abandoned by Indians, stumbled upon by various English and French art enthusiasts, and recovered by archaeologists, under the offices of the Archaeological Survey of India. The earliest was the discovery of several sculptures below ground level at Arjuna’s Penance, by Lord Napier in 1872. A few years later, in 1880, the mostly buried Atiranacanda Mandapam near Tiger cave was extricated from layers of sand, by Alexander Rea. A more recent discovery was of a buried well and some associated sculptures near the Shore temple, in the 1990s. The most recent discovery has been what is called a Sangam era temple near Atiranacanda Mandapam, following the 2004 Indian ocean tsunami.

Sangam era Murugan temple, Saluvankuppam
"Inscribed Rock" in Mackenzie's map

Based on the discovery of a stone spear, speculation was that this was  a temple for Skanda or Murugan, though it doesn’t have an image of the deity. Oddly, in the place of the sanctum, there is a deep pit. Equally oddly, it is a half rock, half structural monument, mostly made of bricks (which bear similarity to pre-Pallava bricks elsewhere in Tamilnadu).

This puzzling monument was already described by Colonel Colin Mackenzie, in 1802, as Inscribed Rock (Monument 33). In 1840, says Walter Eliot, this the inscription was transcribed. Eliot appended the transcript in the 1844 paper authored by himself, Braddock, Taylor and Mahon. The meikeerthi indicates this was inscribed by Kulottunga Chola the third.

After the 2004 tsunami, the ASI discovered a second inscription below the sand level, that of Rashtrakuta king Krishna. But there are no Pallava era inscriptions. Only some Pallava monuments in Mamallapuram have inscriptions, so this is not too odd. For example, Atiranachanda has two Pallava and one Chola inscription, but Tiger Cave has none.

In the book Seven Pagodas of the Coromandel Coast, a collection of papers about Mamallapuram, compiled by  Captain MW Carr in 1869, is this transcript by Mackenzie. There is also a map, which shows the Saluvankuppam area, including Tiger Cave, Atiranachanda Mandapa and this Inscribed Rock (now called Murugan temple). West of the Murugan temple, and north of Atiranachanda Mandapa, is a monument labeled Inscribed Stone, in Mackenzie’s map. Near it is an ASI monument marker(Monument 36).

Mackenzie's Stone

Tamil Inscription on Mackenzie's stone

I suspect this Inscribed Stone is the remnant or component of either a buried or lost temple to Vishnu. The inscription itself is in Tamil an is very brief.

ஸ்வஸ்திஸ்ரீ இச்சகதலதமானார்க்கு மதிதவிட்டாகி மாப்பட்டியில் திருவமிதிக்கு இருமாநிலமும் திருவிளக்கு கழஞ்சு பொன்னும் குடுத்தது

Svastishree iccagathalatamaaanaarkku maditavittaagi maappattiyil tiruvamidikku irumaa nilamum tiruviLakku kazanju ponnum kuduttadu

My reading:

ஸ்வஸ்திஸ்ரீ இச்சகதல
வமிதிக்கு இருமா[நிலமும்
திருவிளக்கு [கழஞ்சு பொன்]
னும்குடு [த்தது]

Translation: SvastiSree. Two maa of land for food (tiruvamudu) and two kalanju of gold for a lamp (tiruvilakku) are donated for this jaga-tala-tam-aanar and uditta-battar and ara-patti-????

The main temple in worship in Mamallapuram is called Sthalasayana: Sthala means place (or  ground); Sayana means reclining. This word is in stark contrast to the usual pose of reclining Vishnu, when he is always AnantaSayana – reclining on Ananta, or Adisesha, his thousand headed serpent. There is no serpent in the temple. In contrast, the Vishnu in Mahishasura Mardhini mandapam, reclines on his serpent : which is how he is depicted almost everywhere else – in Srirangam, Tirumeyyam, Tiruvanathapuram, Tiruvekka (Kanchipuram) etc. Historians say this temple is of perhaps Vijayanagar vintage (13-15 century AD) rather than Pallava era (5-9 century AD).

Between the two Siva shrines of the Shore temple, is a Vishnu shrine, called Narapati SimhaVishnu Graham. Apparently there is an inscription on the lintel, but perhaps it has eroded : I have never seen it. This shrine also has a Vishnu reclining not on the serpent, but on the bare rock. Perhaps this was the original Sthalasayana; some commentators say that it is called Jalasayana by the locals.

Let us quickly look at two other sets of monuments: Five Rathas and Trimurthi mandapam. Trimurthi Mandapam has three shrines, one each for Vishnu, Siva and BrahmaShasta (Skanda or Murugan, wearing his trademark channavira, but standing in Brahma’s place, with rishis rather than warriors on his side). Also there is a Mahishasura Mardhini on the wall, without a separate shrine. It is an interesting grouping of these three gods and the goddess.

Of the five rathas, four are in a row. Two have deities on the back wall in the sanctum – Draupadi ratha has a standing Mahishasura Mardhini sculpture. Dharmaraja ratha, designed to be a three storey temple, has only one completed sanctum, on the top floor, with SomaskandaH on the back wall. Bhima ratha,very incomplete, looks like it was designed to fit Vishnu in reclining pose; but a major flaw in the rock forced the sthapati to leave it incomplete. Whether it was intended for Sthalasayana or Anantasayana, we can only guess. Arjuna ratha also has an empty sanctum, but it has a figure on the back wall, seated on an elephant. Speculation is that it is either Indra or Muruga. Going with the Trimurthi mandapam pattern, I will guess that it is also Muruga. So both sets have temples for the same four gods. I ignore Sahadeva ratha, since it also has an empty sanctum.

Now let us look at the Saluvankuppam complex. The Atiranachanda mandapam is clearly a shrine for Siva – it has a Somaskanda and a lingam in the sanctum, and the inscriptions both say it is dedicated to Atiranachandeshvara. The tiger cave has an empty sanctum, and may not be a temple at all, but a music hall, as speculated by TN Ramachandran in 1933. The cave mouth is surrounded not by tigers but vyaalis : remarkably there is a mini tiger cave, about a mile south of the Shore temple, very similar in structure; it has a shrine featuring Durga or Mahishasura Mardhini. Prof Baluswamy of MCC conjectures that therefor Tiger cave is also a temple to Mahisharura Mardhini.

Atiranchanda Mandapa buried under sand before 1880
Photograph: Internet (perhaps  shared by ASI )

Atiranachanda mandapa 2014

As we noted earlier, the Murugan temple doesn’t have an image of the deity or even a proper sanctum, but it has the stone spear. We can consider the Inscribed stone, the mysterious monument which is the subject of this essay, to be the fourth monument of this Saluvankuppam set. Since the other three are temples to Siva, Durga and Muruga, this must be for Vishnu, in the pattern of Trimurthi mandapam and Five rathas.

Our strongest clue is the inscription itself. It is a donation inscription; land and gold for food offering and a lamp are donated to cagat-tala-tamaanaar and others. Caga is Tamil tatbhavam for jagat; tala likewise for sthala; tamaanaar (tam+aanaar) is unusual and most likely means the person (he who is). So cagat-tala-tamaanaar is  a Tamil phrase for Sthalasayana. It cant be for the Vishnu in either the Shore temple or the Adivaraha cave or anywhere among the main group in Mamallapuram; it must be for a local temple. If intended for any of the other three, why not inscribe on those? There is plenty of space. The most logical explanation is that, this Inscribed stone is part of the temple, waiting to be discovered from its burial under the same sand that buried most of Atiranachanda mandapa and most of the brick temple. The inscription may be of the Pallava era, based on the shape of some letters, though there is no mention of a king.

It is not clear whether this stone is the floor or the roof of a temple. One would expect an inscription to be on the floor, rather than on the roof. You see inscriptions on the floor in several temples in Mallai, including Atiranachanda, Shore temple, Adivaraha and Ramanuja mantapa. But, the level of this Inscribed Stone is almost the same as the roof of the Atiranachanda mandapa, and above the level of the rediscovered Sangam brick temple. Also, it is exteremely uneven for the floor of a temple. And there are no protuberant pillar bases. So it could possibly be the roof.

So, summarizing, there are three reasons why I think Mackenzie’s inscribed stone, is a buried Vishnu temple.

1.  Caga-tala –tamaanaar  inscription

2.  Level of the sand

3.  Grouping  of four

There are also several arguments against my conjecture.

The first and most obvious is wishful thinking: it would be awesome to just find an undiscovered monument, especially  of the Pallavas.

The second is that, I am unlikely to have stumbled upon something that experts, especially archaeologists, have missed. Wouldn’t Rea or Hunter or the 2004 ASI team have excavated it, if they suspected something?

The third is that, it seems unlikely for an inscription to be on the roof, rather than floor of a temple. It may have been a brick monument that has completely gone, not of Pallava but later era. There is an isolated and ignored torso of  a murthi, perhaps of Vishnu, cast aside among the bushes near the Atiranachanda mandapa. It looks like the remnant of a standing Vishnu. So there may be no monument underground.

These are feeble objections; someone else may have far much better reasons to consider my conjecture wrong.

But I hope someone at ASI believes me and sanctions an exploration. If there is nothing, no harm done, except some wasted time, money and labour. But what if there is a Pallava temple, and a full Sthalasayana?? Can we afford to ignore the possibility?

Related essays

Babington’s Gift – the third Atiranachanda inscription

Lingodbhavasculpture near Shore temple

Essays on Art

Essays on History


2000 Years ofMamallapuram – lecture in Tamil

Babington's third inscription - joint lecture with Dr Nagaswamy