Dutchman Stevinus showed that the pressure at the bottom of a column of liquid is proportional to the height of the column, and not to its bulk, about 1634. He also studied oblique forces, and the balancing of such that could bring about "stable equilibrium".
Evangelista Torricelli, an Italian student of Galileo, discovered in 1643 that any fluid will be supported at a definite height, according to its relative weight, as compared with air. He realized that a mercury column, 30 inches in height, in a long glass tube inverted in a cup of mercury, was being supported by air pressure exerted on the mercury in the cup. When he observed that this height changed with the weather, he had invented the mercury barometer. His creation of a vacuum, above the mercury in the tube, astonished philosophers, who had thought that nature abhored a vacuum and would prevent it.
Blaise Pascal, a French mathematician, physicist, and religious philosopher, constructed a calculator in 1644 to assist his father, who was involved in local administration, in tax computations. Around 1646, he proved his law that pressure applied to a confined liquid is transmitted undiminished through the liquid in all directions regardless of the area to which the pressure is applied. Around 1653, he laid the foundations for the theory of probabilities, including the creation of "Pascal's Triangle" of coefficients of (a=b) raised to the nth power.
Jean Ray from France concluded from his experiments that every piece of material has a given weight, including air and fire.
The Merchant Adventurers were incorporated again in 1643 to have a monopoly. It was required to admit into membership for 100 pounds anyone free of London and bred as a merchant, and for 50 pounds any non-inhabitant of London. The penalty for trading for one who was not free of the corporation was forfeiture of his goods.
In 1648, the House of Commons abolished the monarchy and in 1649 the House of Lords. Also in 1649 it declared that England "should thenceforth be governed as a commonwealth and free state by the supreme authority of this nation, the representatives of the people in Parliament." It made a new constitution.
John Milton defended the Commonwealth as superior to the monarchy because it could not deteriorate into tyranny in his books: "First Defense of the People of England" in 1651, and "Second Defense" in 1654. He lauded Cromwell as great in war and great in peace, and exemplifying the principle that "nature appoints that wise men should govern fools".
Thomas Hobbes, the son of a clergyman, and tutor to students, wrote "Leviathan" in 1651 on his theory of sovereignty. Hobbes thought that states are formed as the only alternative to anarchy, barbarism, and war, so that supremacy and unity of a sovereign power is essential to a civilized life and the protection of the citizenry. A sovereign may be a man or body of men as long as his or its authority is generally recognized. There must be a social contract among the citizenry to obey a certain sovereign. To avoid religious conflict, there must be a complete subordination of the church to the state and the religion of a state must be dependent upon its secular sovereign. Hobbes thought that knowledge of the world came through experience and not reason alone. Only matter exists, and everything that happens can be predicted in accordance with exact, scientific laws. He regarded human societies as purely mechanical systems set in motion by human desires. He saw self interest as the mainspring of moral law. Conflicting self interests transformed into a lawful system of agreements. Hobbes opined that all power really originated in the people and that the end of all power was for the people's good.
On the other hand, James Harrington, who wrote "The Commonwealth of Oceana" in 1656, opined that a stable society depended on a direct relationship between the distribution of property and political power; no one with property worth more than 2,000 pounds should be allowed to acquire more and property should be divided among children. A senate of mature property owners were to make and debate the laws while an assembly elected by universal suffrage was to vote on them because "a popular assembly without a senate cannot be wise and a senate without a popular assembly will not be honest". A third of the Senate would turn over every year. John Milton defended the execution of the King in "The Tenure of Kings and Magistrates" in which he maintained that the people may "as often as they shall judge it for the best either to choose him or reject him or depose him, though no tyrant, merely by the liberty and right of freeborn men to be governed as seems to the best". He also wrote in favor of liberty of the press. Ordinary speech found its way into prose writing.
Lands of more than 700 Royalists, including church lands, were confiscated and sold or leased by county committees. Many Royalists put their lands into trusts or turned them over to relatives or sold them outright to prevent confiscation. It was an upheaval comparable to the dissolution of the monasteries. Also, specified Papists who had taken up arms against the realm lost their lands and goods and money and rents and two-thirds of their personal estates. But allowance was made for the maintenance of their wives and children.