Barometer (1644–1698): During the 17th century there were three major inventions and discoveries that focused on the nature of air. These were the vacuum pump, Boyle’s Law on air pressure, and the barometer (see BOYLE’S LAW; VACUUM PUMP). Together, these instruments allowed scientists to finally examine the properties of air and address some of the historical questions regarding the nature of a vacuum. To the ancient Greeks a vacuum was an unnatural phenomenon. In fact, the Greek philosopher Aristotle believed that nature abhors a vacuum and that the void spaces between objects were filled with an element called ether, a fine compound that could pass through virtually all other materials. While it was recognized by the ancient Greeks that air possessed weight, they did not understand the concept of pressure (see BOYLE’S LAW). Such misconceptions would not be confined to the Greeks, as the renowned scientist Galileo appears not to have understood air pressure as late as the 17th century.
In the early part of the 17th century scientists remained in conflict as to the very existence of a vacuum. Early experiments focused primarily on the creation of vacuums and not on direct measurement of air pressure. Several experiments, most notably the one performed by the Italian physicist-astronomer Gasparo Berti (ca. 1600–1643), utilized air pumps to create vacuums at the top of tubes (see VACUUM PUMP). The first steps toward the creation of a device to study air pressure, the barometer, would begin with experimentation by the Italian scientists Evangelista Torricelli and Vincenzo Viviani (1622–1703). As with many scientific discoveries, it was an industrial problem that promoted the development of the device. For some time workers in mines had been experiencing problems removing water from the bot-