What took electromagnetism so long to be discovered?

at least the electricity could be harnessed on earth

On 21 April 1820, during a lecture, Ørsted noticed a compass needle deflected from magnetic north when an electric current from a battery was switched on and off, confirming a direct relationship between electricity and magnetism.[3] His initial interpretation was that magnetic effects radiate from all sides of a wire carrying an electric current, as do light and heat. Three months later he began more intensive investigations and soon thereafter published his findings, showing that an electric current produces a circular magnetic field as it flows through a wire. This discovery was not due to mere chance, since Ørsted had been looking for a relation between electricity and magnetism for several years. The special symmetry of the phenomenon was possibly one of the difficulties that retarded the discovery.[4]

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For hundreds of years after Galileo stressed the importance of empirical evidence experiments often remained little more than parlor tricks performed for wealthy audiences and given elaborate metaphysical explanations to satisfy their curiosity. Newton himself practiced alchemy and the fact his theory of motion was 95% accurate blew everybody's mind.

Are you implying Newton got motion right by accident? If not, what are you saying?

Newton and the other members of the Royal Society were conducting rigorous experiments in mechanics on the lines of Galileo less than a hundred years after Galileo's death. Newton never proposed any "theory of motion". He asserted the three laws as axiomatic (and attributed their discovery to the joint efforts of Galileo and the other members of the Royal Society). What blew people away was his case for "Universal Gravitation". Before Newton no one was sure if gravity was a purely terrestrial phenomenon or if other planets and the sun also had it. He tediously proved that if we ascribed gravity to all masses it explained the motion of the planets.

In 1687, with the support of his friend the astronomer Edmond Halley, Newton published his single greatest work, the 'Philosophiae Naturalis Principia Mathematica' ('Mathematical Principles of Natural Philosophy'). This showed how a universal force, gravity, applied to all objects in all parts of the universe.

Italian physician Gerolamo Cardano wrote about electricity in De Subtilitate (1550) distinguishing, perhaps for the first time, between electrical and magnetic forces.

Toward the late 16th century, a physician of Queen Elizabeth's time, Dr. William Gilbert, in De Magnete, expanded on Cardano's work and invented the New Latin word electricus from ἤλεκτρον (elektron), the Greek word for "amber". . . .
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Gilbert undertook a number of careful electrical experiments, in the course of which he discovered that many substances other than amber, such as sulphur, wax, glass, etc., were capable of manifesting electrical properties.
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Are you implying Newton got motion right by accident? If not, what are you saying?

Newton and the other members of the Royal Society were conducting rigorous experiments in mechanics on the lines of Galileo less than a hundred years after Galileo's death. Newton never proposed any "theory of motion". He asserted the three laws as axiomatic (and attributed their discovery to the joint efforts of Galileo and the other members of the Royal Society). What blew people away was his case for "Universal Gravitation". Before Newton no one was sure if gravity was a purely terrestrial phenomenon or if other planets and the sun also had it. He tediously proved that if we ascribed gravity to all masses it explained the motion of the planets.

In fact, Galileo died 8 January 1642, and Newton was born 25 December the same year (according to the Julian calendar). Newton's birthday was 4 January 1643 in the 'corrected' Gregorian calendar. (The Gregorian calendar was not adopted in England until 1752.) http://www-history.mcs.st-and.ac.uk/...es/Newton.html

http://www.bbc.co.uk/history/histori...on_isaac.shtml

For hundreds of years after Galileo stressed the importance of empirical evidence experiments often remained little more than parlor tricks performed for wealthy audiences and given elaborate metaphysical explanations to satisfy their curiosity. Newton himself practiced alchemy and the fact his theory of motion was 95% accurate blew everybody's mind. Slowly a more methodical mechanistic approach became a lot more attractive, but it still required time for the idea to catch on and the genius of Volta and Faraday as jedshrfu points out to take that next step.

A similar trend was the advent of Big Science in the 1920s when industries began investing heavily into researching washing machines, cars, and all the other gizmos of modern civilization. They could have done so at any point in history, but suddenly it became a sure bet with the newly acquired 95% literacy rate and success of such inventors as Thomas Edison. At one point Henry Ford raised the salary of his assembly line workers from a dollar a day to five dollars just so he could sell him the same cars they made. It's very much a pull-yourself-up-by-your-bootstraps affair that sometimes takes awhile to get right.

Not sure I follow your post, but while it's true science progresses in fits and starts I wouldn't dismiss things that happened "hundreds of years" after Galileo. As Astronuc mentioned, significant progress was made in the 17th century. And Newton was not simply playing parlor tricks!

From a historical point of view, I don't see how people like Newton were studying the solar system and the effects of gravity on the moon before figuring out the electromagnetic phenomenon. It seems like it would be much harder to study the orbits of the planets than electricity, since at least the electricity could be harnessed on earth, whereas figuring out jupiters orbital patterns would be extremely difficult.

1600 - Static Electricity (De Magnete)
In the 16th century, William Gilbert(1544-1603), the Court Physician to Queen Elizabeth I, proved that many other substances are electric (from the Greek word for amber, elektron) and that they have two electrical effects. When rubbed with fur, amber acquires resinous electricity; glass, however, when rubbed with silk, acquires vitreous electricity. Electricity repels the same kind and attracts the opposite kind of electricity. Scientists thought that the friction actually created the electricity (their word for charge). They did not realize that an equal amount of opposite electricity remained on the fur or silk. Dr. William Gilbert, realized that a force was created, when a piece of amber (resin) was rubbed with wool and attracted light objects. In describing this property today, we say that the amber is "electrified" or possesses and "electric charge". These terms are derived from the Greek word "electron" meaning amber and from this, the term "electricity" was developed. It was not until the end of the 19th century that this "something" was found to consist of negative electricity, known today as electrons.

Gilbert also studied magnetism and in 1600 wrote "De magnete" which gave the first rational explanation to the mysterious ability of the compass needle to point north-south: the Earth itself was magnetic. "De Magnete" opened the era of modern physics and astronomy and started a century marked by the great achievements of Galileo, Kepler, Newton and others.

Gilbert recorded three ways to magnetize a steel needle: by touch with a loadstone; by cold drawing in a North-South direction; and by exposure for a long time to the Earth's magnetic field while in a North-South orientation.

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The OP asked why electromagnetism was ignored for so long. Even by this logic it wasn't so much ignored as merely difficult to separate the wheat from the chaff and academia was understaffed for the job. Sure, we'd all like to claim academia has never had its own quacks and nut cases, funding problems, and all sorts of problems, but it has never been true and in Newton's day it was even more of a problem. The amazing thing is how rapidly they made progress under the conditions and to this day Faraday is celebrated as having used the equivalent of "Bear claws and stone knives" to work his magic.

Before Galileo no one appreciated scientific rigor. He gave that to science and he also simultaneously managed to make himself the center of the huge storm of church vs science controversy with his views on a heliocentric 'universe'. He made planetary motion the hot issue and anyone who was anyone went after that fruit, so to speak. Newton plucked it. Electromagnetism came next and between Faraday and Maxwell it was firmly integrated into classical physics.

So, the reason may well lie in the timing of the invention of the telescope. Without it Galileo might have turned his spare attention to magnets and amber. You never know.