The quadrant is an instrument used to simplify astronomical calculations and to make observations. Developed by Isaac Carver, a student of Edmund Gunter, in 1706. The quadrant is used to observe and measure astronomical phenomena, to perform the basic tasks of surveying. Designed to work at specific latitudes (in this case 38-41 N), the quadrant …
Continue reading “Tools of the Surveyor — Carver’s Quadrant”
Gunter’s Rule was invented by Edmund Gunter in 1620 to operationalize the work John Napier did with Logarithms. Napier published a table of logarithms in 1614 with which one can replace complex multiplication and division with simpler addition and subtraction of the equivalent logarithms. This is an improvement if you must calculate by hand but …
The larger end of a bird’s egg contains an air cell that forms when the contents cool and contract after the egg is laid. A freshly laid egg has a relatively small air cell, but the size increases with time since the shell is slightly porous. A fresh egg, however, is dense enough that it …
In a 1716 issue of the Philosophical Transactions of the Royal Society, Edmund Halley explained how it was possible to use transits of Venus or Mercury to determine the astronomical unit by measuring the apparent solar parallax between different points on the surface of the Earth. Unfortunately, the next transits would occur in 1761 and …
Continue reading “The 1769 Transit of Venus was Used to Compute the Astronomical Unit”
Before the invention of modern refrigeration, people rarely drank anything ice-cold. Beer was traditionally drunk it at “room temperature” or cellar temperature. Drinking any “ice-cold” beverage was a rare luxury reserved only for the extremely wealthy who would harvest and store natural winter ice in deep cellars. In the German states[1] beer was fermented and …
Wind is perhaps one of the most obvious weather phenomena and was of critical importance to commerce in the 18th Century. Wind propels not just ships at sea but the earliest industrial processes like milling grain and pumping water (especially in the Netherlands).There is some controversy over the invention of the anemometer. Some historians suggest …
Continue reading “Early Meteorology — The Deflection Anemometer”
The weather glass is a small open barometer filled with water. It is a simple instrument designed to indicate atmospheric pressure rises and falls as the water in its spout falls or rises. It does not provide quantitative measurements of atmospheric pressure but indicates changes. Falling water in the glass (water pushed into the sealed …
Galileo Galilei is credited with the invention of the thermoscope, a device for gauging heat. But it’s not the same as a thermometer. It couldn’t measure temperature because it had no scale. Today, we see Galileo Thermometers, but these are modern inventions dependent upon ultra-modern mass and density measurement. Galileo’s thermoscope simply demonstrated that the …
By the late 18th Century, the emerging science of meteorology—closely aligned with the study of gases—was focused on major advances in understanding evaporation, latent heat, and water vapor in the air. The earlier Aristotelian study of storms was being superseded by the systematic measurement of temperature, pressure and atmospheric moisture with an aim to PREDICT those …
Clearly the Trump Administration wants a war. They are insistent upon MISLEADING and UNTRUTHFUL telling of history. Its time we start really protesting and shut-down Philadelphia in preparation for the semiquincentennial. Come to INHP on Saturday between 12 and 4pm as we tell the REAL HISTORY of America and the President’s House. We will continue …
Michael Carver -- Historical Interpreter/Reenactor 