the pressure changes, the effect is described by the following equation:
Pt = P0[1 + 0.003665 t0]
where P0 is the pressure at the temperature of melting ice and Pt the pressure at t0. If pressure and volume both change, then
PtVt = P0V0[1 + 0.003665 t0]
The student should be warned that this law of Charles is very accurately true for all gases throughout a moderate range of pressures, but is not exactly true for any gas, and does not hold at all in the case of vapors.
Charles Martel, meaning Charles the Hammer, was born about 688. He was mayor of the palace under the last Frankish kings of the Merovingian dynasty, and was the real ruler of the Franks. He carried on wars with the Saxons, the Alamanni and the Bavarians; but his great service to Europe was his driving back of the Saracens. They had already taken Bordeaux and had advanced to the Loire, when Charles met them in 732, and after a hard-fought battle wholly defeated them. This was one of the most important victories in the world's history, and probably kept Europe from becoming a Mohammedan country and being to-day no further advanced than Arabia. Charles died in 741.
Charleston, the chief city of South Carolina, was founded in 1670 as an English colony. It was captured by the British in 1780. The first ordinance of secession was passed here, and the reduction of Fort Sumter in its harbor was the first conflict of the Civil War. In 1861 nearly half of the city was burned to the ground, and it was in a state of siege during the last two years of the war. Then again, in 1886, a heavy earthquake visited the city and wrought $8,000,000 of damage.
Charleston is situated on a peninsula, formed by the Ashley and Cooper Rivers, while a third river, the Wando, unites with the Cooper at the city. The estuary formed by these rivers makes a magnificent harbor. It is even regarded as the safest on the Atlantic coast.
Fort Moultrie, at Sullivan's Island on the eastern side of the harbor, is one of the best equipped defenses on the coast. It and the naval station at Charleston, which occupies a tract on Cooper River, have cost the government several millions.
Charleston's commerce was almost destroyed by the Civil War, but much of that which entered other channels has been recovered, and the terminal docks for two ocean-freight lines which were established in Charleston in 1901 have also increased the city's commercial prestige. Eleven manufactories are engaged in producing phosphate fertilisers, which is the leading industry; others of importance are tobacco, foundry and machine-shop products, oil and rice milling, bagging-factories, turpentine-casks and baskets for shipping vegetables and fruits.
Charleston has good public and parish school systems, and for higher education, the Charleston and Meninger High School, Academy of Our Lady of Mercy, Smith's school for young ladies, the South Carolina Military Academy, a state institution established in 1843, the state Medical College and many others.
The city has 60 churches and many charitable institutions. The buildings of note are the postoffice, built of Carolina granite, and the U. S. Custom-House erected of white marble. Population, 58,833.
Charleston, capital of West Virginia and county seat of Kanawha County, is situated on the Kanawha River at its junction with the Elk. The Kanawha has an excellent system of locks and dams, which afford facilities for shipping coal from the rich New River mines. Charleston is the center of trade for large coal and lumber interests. Its industries include woolen-mills, machine-shops, boiler-works, iron-foundries, steel-plants, dye-works, marble-works, wagon-shops, glass-works, furniture-factories and one of the largest axe-factories in the world. It has many fine public buildings, among which are the Capitol and Capitol Annex, Court-House, Y. M. C. A. building, modern and well-equipped houses and handsome churches. Population, 22,996.
Charlestown, Mass. Charlestown is situated at the mouth of the Charles River, opposite the old city of Boston. In 1873 it was annexed to the city of Boston. At that time it had a population of 28,000. It is the scene of the first real battle of the Revolution, that of Bunker Hill.
