Roman central heating worked slightly differently, but the goal was the same. A ground level furnace was used to create hot air which circulated beneath a thin floor raised up on pillars of tiles â this system was called a hypocaust. Not only was this central heating, it was underfloor heating! Smoke and fumes from the furnace were channelled off via flues so as not to pollute the heated space above. The same method was used to heat the waters in bath houses (yes, the Romans gave us hot baths too). Concrete. Opus caementicium (Roman concrete) was made from quicklime, pozzolana and an aggregate of pumice.
WHAT THEY MEAN: The most recent Census count (which dates to 2008) found the 227 million Americans above the age of five speaking only English at home. Another 55 million spoke 379 other languages.
Spanish is the official or national language in Spain, Equatorial Guinea, and 19 countries in the Americas. Speakers in the Western Hemisphere total some 418 million. In the European Union, Spanish is the mother tongue of 8% of the population, with an additional 7% speaking it as a second language.Spanish is the most popular second language learned in the United States.here are an estimated 470 million Spanish speakers with native competence and 560 million Spanish speakers as a first or second language, including speakers with limited competence and 20 million students of Spanish as a foreign language.