Static electricity was being discerned. It had been noticed that shaking a mercury barometer produced a strange glow in its "vacuum". Experiments showed that a glass rubbed in vacuo would shine brightly and that an exhausted glass globe rapidly whirled on a spindle and rubbing against the hand produced a brilliant glow. And further, as Newton wrote: "if at the same time a piece of white paper or white cloth, or the end of ones finger be held at the distance of about a quarter of an inch or half an inch from that part of the glass where it is most in motion, the electric vapor which is excited by the friction of the glass against the hand, will by dashing against the white paper, cloth, or finger, be put into such an agitation as to emit light, and make the white paper, cloth, or finger, appear lucid like a glowworm". In the study of electricity, conductors and insulators were recognized. There were demonstrations of electrical phenomenon such as seeing brandy ignited by a spark shooting from a man's finger and transferring an electrical impulse among a circle of people by their holding hands. Electricity was stored in an early type of capacitor. Benjamin Franklin "caught" lightning with a sharp pointed wire attached on top of a kite which led down to a key. When a thunder cloud electrified the kite, a charge could be seen coming from the key to an approaching finger. This charge was stored and then reproduced to create the same feeling of electrical transference among hand-holders as a rubbed glass globe, thereby illustrating that it was the same phenomenon as electricity. This countered the theological belief that thunder and lightning were signs of divine displeasure or the work of the devil. He invented the lightening rod, which was then used to protect houses. About ten years later, the first lightening rod on an English church was erected. Franklin theorized that there were electric charges everywhere and designated them as positive or negative. He observed that opposite charges attracted each other, but that like charges repelled each other. In 1766, Joseph Priestly did an experiment suggested by Franklin and showed that electrical force follows the same law as gravitational force; that is, that the attraction or repulsion between two electrical charges varies inversely to the square of the distance between them.
Joseph-Louis LaGrange from France developed differential equations. Natural history museums were established. A group split off from the Royal Society to show collections of curiosities.
In 1754, a self-educated mechanic founded the Society for the Encouragement of Arts, Manufactures, and Commerce. It had sections on agriculture, manufactures, mechanics, chemistry, liberal arts, and trade and colonies. It sponsored contests at which prizes were given, such as that in 1761 for the best invention of a machine that would spin six threads of wool, flax, cotton, or silk at onetime with only one person attending it.
Machines still mostly relied on human, animal, and water power.
Abraham Darby was a Quaker and millwright who made large cooking pots of iron, which cost less than bronze. Around 1713, he experimented with various substances to take the place of wood charcoal in iron smelting. Coal was a remote possibility. In forging or working metals coal had more or less the same qualities as wood charcoal, but this was not the case in smelting ores, especially iron ore. Coal contained sulphur compounds which caused the iron ore to deteriorate. So he controlled the burning of coal to burn out these impurities, which produced coke. His son took over after his death and improved the methods of coking, strengthened the bellows, and added ore limestone and other reagents to the mixture. By 1756, his large blast furnace using both pit coal and wood charcoal was very productive. He made iron goods of such quality as those previously imported.
In 1767, Richard Reynolds replaced the wooden rails connecting a blast furnace to mines with cast iron rails. He had apprenticed as a grocer and then became a partner in a large ironworks of Darby, whose daughter he married. After Darby died and before Darby's sons became of age, Reynolds was in charge of the ironworks. He cast cylinders of the early steam engines.
In 1749 John Roebuck, a physician and son of a prosperous manufacturer of Sheffield goods, found a cheaper way to manufacture sulphuric acid. He did this by using leaden chambers instead of glass globes to collect the vapor from burning nitre and sulphur over water. This reduced the cost of sulfuric acid to one-fourth of its previous cost, so that sulfuric acid came to be used to bleach linen instead of sour milk. He also made cast iron into malleable iron by smelting iron using coke from pit-coal instead of charcoal. But flooding in his mines and further ventures resulted in his ruin and bankruptcy.
Thomas Newcomen, a Baptist ironmonger, blacksmith, and locksmith, supplied iron tools to mine workers. He was aware of the problem of flooding of mines and the awkward system of pumps which were used one above the other and were powered by teams of horses. He made a very valuable contribution to power generation by inventing the atmospheric pressure steam engine around 1712. He did this by connecting theory with experiment, through the use of scientific knowledge, especially the Royal Society's investigation into atmospheric pressure. First cold water was poured on a cylinder in which a piston could move up and down. This caused steam inside the cylinder to cool and condense into water. The vacuum created inside the cylinder under the piston caused atmospheric pressure on top of the piston to push the piston down. The piston was attached by a rod to the end of a beam which end then swung down from a point on a vertical stand to which it was attached. When the beam swung, its other end, which was attached to a rod connected to a pump, rose, thus working the pump. Then steam from water heated in a boiler under and communicating with the cylinder was allowed into the cylinder under the piston. This decreased the atmospheric pressure on the piston from above and allowed the piston to rise by a counterweight on the rod over and connecting to the pump. Boys opened and closed the steam valve, which let steam into the cylinder from below, and the water valve, which let cold water pour on the cylinder from above. Then the boys were replaced by the valves being connected to the oscillating beam which caused them to open and close at perfectly regular intervals. A story gives the credit for this improvement to an inventive valve boy who wanted to play with his friends. In 1712, the mining industry used this steam engine to pump water out of mine-shafts which had flooded. These engines were also used to supply water to reservoirs locks at canals, and drinking water facilities in towns. One such engine developed power equivalent to fifty horses working at one sixth the cost. It was the first automatic machine since the clock.
Then James Watt invented the steam engine which used steam as a force acting on the piston. Watt made his living making scientific instruments for Glasgow University. Around 1764, he was fixing one of Newcomen's engines belonging to the university, when he saw its inefficiencies, such as the loss of heat when the cylinder was cooled. He saved this heat energy by having the steam condensed in another vessel distinct but connected to the cylinder. This condenser was kept constantly cool by cold water. So the condensed steam was pumped back into the boiler and it circulated continuously, thus obviating the need for constant resupply of water. In order to avoid the necessity of using water to keep the piston air-tight, and also to prevent the air from cooling the cylinder during the descent of the piston, he used the expansion of the steam to push the piston instead of atmospheric pressure. Then, in order to expand the use of the steam engine beyond that of a pump, he converted the oscillating motion of the beam into rotary motion. He formed a partnership with John Roebuck, who had a two-thirds interest. But when Roebuck needed money, he sold his interest to Matthew Boulton. Boulton wanted better power that that of his watermill for his workshops that made metal buttons, watch chains, shoebuckles of engraved steel, ornamental bronzes, vases, chandeliers, tripods, silver and plated wares, and imitation gold and tortoiseshell work. In dry weather, about eight horses were needed to aid in driving the machinery. A steam pump could pump water from the bottom of the watermill to the top to be used again. He had built up this factory of five buildings and six hundred workers, with 9,000 pounds derived from his marriage to an heiress. By 1774, the partnership had built a model steam engine with rotary power whose design could be sold. The price of the engine was set as the amount of money saved on fuel costs in the first three years of its operation. This machine was a relatively economical user of energy, capable of performing almost any kind of work.
About 1750, John Wilkinson, the son of a farmer who also oversaw an iron furnace, substituted mineral coal for wood charcoal in the smelting and puddling of iron ore. In 1766 he made it possible to transport coal out of mines on rail wagons drawn by horses. As father of the iron industry, he made iron chairs, vats for breweries and distilleries, and iron pipes of all sizes. He provided Watt with metal cylinders of perfectly accurate shape, which were necessary for the smooth working of Watt's steam engine. In 1775 he bought a pumping steam engine from Boulton and Watt's company for his ironworks. It pumped three times as fast as Newcomen's engine.