Primitive Astronomical Notions
On the astronomical side the most obvious fact is the division of time into periods of light and darkness by the apparent motion of the sun about the earth.
With closer attention it must soon have been observed that the relative length of day and night gradually changes, and that this change is attended by a wide range of remarkable phenomena.
At the time of shortest days, vegetable and animal life (in the north temperate zone) is checked by severe cold.
With gradually lengthening days, however, snow and ice sooner or latter disappear, vegetable is revived birds return from the warmer south, all nature is revived, birds return from the warmer south, all nature is quickened.
The longest days and those which succeed them are a period of excessive heat and of luxuriant vegetation, followed by harvest as the days shorten, towards the completion of the great annual cycle.
In time, closer observers, noting the stars, discovered hat corresponding with this great periodic change are gradual variations in the starry hemisphere visible at night, that in other words the sun’s place among the stars is progressively changing, that it is in fact describing a path completed in a large number of days, which after many years of counting is found to be 365.
It is also found that the midday height of the sun above the southern horizon shares in the annual cycle.
The determination of the number of days on the year is a matter of very gradual approximation, possible only to men who have already attained some command of numbers and the habit of preserving records extending over a long series of years.
For there is now well marked beginning of the year as of the day.
An erroneous determination of the number of days becomes apparent only after a number of years increasing with accuracy of the original approximation.
Still another natural period is introduced by the motion of the moon, which seems like the sin to have a daily motion about the earth, and also to describe a closed path among the stars in a period of about 29 days.
Unlike the sun, however, the moon has during this period a remarkable change of apparent shape and luminosity from “new” to “full” and back again.
The difficulty of expressing the precise length of the month and the year in days, causing the imperfection of of early calendars, has on the other hand reacted to the advantage of mathematical astronomy by demanding more and and more precise both in observation and in the computation based on it.
Primitive Astronomical Notions
Monday, November 2, 2009
Thursday, October 15, 2009
Frederick William Herschel
Frederick William Herschel
Frederick William Herschel (1738-1822) is perhaps most famous for his discovery of Uranus, the first planet found since antiquity, on March 13, 1781.
Herschel was born in Hanover, Germany and became well known as both as musician and an amateur astronomer.
He immigrated to England in 1757, and with his sister Caroline, began making the most advanced instrument of the time. The discovery of Uranus was made using a home made 15.7 cm (6.2 in) reflector.
His later creations included telescope of the day – a 12 m (40 ft) long instrument with a 1.9 m (48 in) mirror.
Appointed the personal astronomer to King George III (after whom he named the new planet), he later discover two satellites of Uranus (Titania and Oberon) in 1787, followed by two moons of Saturn (Mimas and Enceladus) in 1789.
In 1800, he discovered what he called “caloric rays” (now known as infrared radiation) during studies of the “rainbow” created when light is divided into its color by a prism. It was the first time that someone had shown the existence of forms of light that our yes cannot see.
At the very end of his life he was elected to be the first president of the newly founded Royal Astronomical Society.
Frederick William Herschel (1738-1822) is perhaps most famous for his discovery of Uranus, the first planet found since antiquity, on March 13, 1781.
Herschel was born in Hanover, Germany and became well known as both as musician and an amateur astronomer.
He immigrated to England in 1757, and with his sister Caroline, began making the most advanced instrument of the time. The discovery of Uranus was made using a home made 15.7 cm (6.2 in) reflector.
His later creations included telescope of the day – a 12 m (40 ft) long instrument with a 1.9 m (48 in) mirror.
Appointed the personal astronomer to King George III (after whom he named the new planet), he later discover two satellites of Uranus (Titania and Oberon) in 1787, followed by two moons of Saturn (Mimas and Enceladus) in 1789.
In 1800, he discovered what he called “caloric rays” (now known as infrared radiation) during studies of the “rainbow” created when light is divided into its color by a prism. It was the first time that someone had shown the existence of forms of light that our yes cannot see.
At the very end of his life he was elected to be the first president of the newly founded Royal Astronomical Society.
Wednesday, September 30, 2009
Ancient Weight and Measures
Ancient Weight and Measures
Measurement, fundamental in science, had had its origin in trade and construction. The values of weights and measures in the Ancient East are known either from the actual instruments or from other sources, units of the same name differing considerably in value from place to place.
The oldest known stone weights are from a Sumerian temple at Lagash (about 3000 BC), each inscribed, “1 mana, Dudu High priests,” – in our scale about one ounce.
A later Assyria scale included the shekel, the mana = 60 shekels (about 1.1 lb.), and the talent = 60 mana.
The early Sumerian carpenters used a scale of digits equaling 0.65 inch.
The Babylonian cubit (form-arm) was 20.6 inches in our measure, and was divided into 30 digits.
The higher units were sexagesimal, ending in a parasang, or league, of about 3.5 English miles.
The Egyptian used decimal systems of weights and measures. The largest unit of weight, for measuring wheat, was about two pounds.
The cubit of the Pyramid Age, nearly the same length as the Babylonian cubit, was divided into hundredths.
But apparently for the convenience of workmen, the scale was usually marked also approximately into 7 palms, a palm being 4 digits.
The two systems were incommensurate, like our yard and meter.
Ancient Weight and Measures
Measurement, fundamental in science, had had its origin in trade and construction. The values of weights and measures in the Ancient East are known either from the actual instruments or from other sources, units of the same name differing considerably in value from place to place.
The oldest known stone weights are from a Sumerian temple at Lagash (about 3000 BC), each inscribed, “1 mana, Dudu High priests,” – in our scale about one ounce.
A later Assyria scale included the shekel, the mana = 60 shekels (about 1.1 lb.), and the talent = 60 mana.
The early Sumerian carpenters used a scale of digits equaling 0.65 inch.
The Babylonian cubit (form-arm) was 20.6 inches in our measure, and was divided into 30 digits.
The higher units were sexagesimal, ending in a parasang, or league, of about 3.5 English miles.
The Egyptian used decimal systems of weights and measures. The largest unit of weight, for measuring wheat, was about two pounds.
The cubit of the Pyramid Age, nearly the same length as the Babylonian cubit, was divided into hundredths.
But apparently for the convenience of workmen, the scale was usually marked also approximately into 7 palms, a palm being 4 digits.
The two systems were incommensurate, like our yard and meter.
Ancient Weight and Measures
Tuesday, September 8, 2009
The Antiquity and Ancestry of Man
The Antiquity and Ancestry of Man
The history of human culture, in which the history of science is an important, reveals at first a very slow growth with roots in the remote past.
In his various biological aspects man shows evidence of descent from ancestor related to the great apes.
Many facts suggest a vast area in south central Asia north of the Himalayan mountains as the place where the human stem arose.
The time when our ancestors became really human probably could not be stated definitely, even if all the circumstances were known, for the change must have been a very gradual one.
However, it certainly was completed before the beginning of the Pleistocene.
The geological epoch, following the Pliocene and preceding our own Recent Epoch, was distinguished by extraordinary cooling of the earth.
Four times great ice sheets spread southward over lands of the northern hemisphere, and four times they related.
During each of these Ice Ages, distinctive mammals appeared, some of gigantic proportions, and their skeleton, buried by dust storms or in the sediments of the swollen of the warm interglacial ages, enable geologist to recognize deposits laid down in any one age.
On other evidence, geologists estimate the length of these ages in years and the whole epoch is believed by American authorities to have lasted a million years ending about twenty-five thousand years ago.
Very early in the Pleistocene primitive men were living in widely separated localities, probably migrants escaping competition with more progressive races at home.
The most primitive of these is the Trinil man (Pithecanthropus) of Java. He was very ape-like, but recent discoveries (1937) shown anatomical features that distinctively human.
There is however no evidence of distinctively human behavior. It is different with Peking man (Sinanthropus), who inhibited caves eastern China at about the same time.
He had larger brain, and he made tools and fire, - activities as distinctively human as articulate speech.
When he learned a kindle a fire from sparks that flew as he chipped flints to make his crude implements, he made the first application of a physical principle to human needs.
Perhaps earlier in time, but with more modern features the Piltdown man (Eoanthropus) was established in southeastern England in the Pliocene or earliest Pleistocene.
A somewhat later type, of Mid-Pleistocene age, the Neanderthal, pursing the great beasts, overran Europe during the second interglacial period. Around their camp fires they made the first completely flaked flint implement, the hand ax- tool characteristic of the Old Stone Age, Paleolithic.
They in turn, gave way during the last Ice Age, perhaps 150,000 years ago, to modern man Homo sapiens, represented by the Brunn and Co-Magnon races.
The latter left in numerous cave dwellings implements of flint and bone and drawing and sculptures, showing fine powers or observation and great manual dexterity.
The Antiquity and Ancestry of Man
The history of human culture, in which the history of science is an important, reveals at first a very slow growth with roots in the remote past.
In his various biological aspects man shows evidence of descent from ancestor related to the great apes.
Many facts suggest a vast area in south central Asia north of the Himalayan mountains as the place where the human stem arose.
The time when our ancestors became really human probably could not be stated definitely, even if all the circumstances were known, for the change must have been a very gradual one.
However, it certainly was completed before the beginning of the Pleistocene.
The geological epoch, following the Pliocene and preceding our own Recent Epoch, was distinguished by extraordinary cooling of the earth.
Four times great ice sheets spread southward over lands of the northern hemisphere, and four times they related.
During each of these Ice Ages, distinctive mammals appeared, some of gigantic proportions, and their skeleton, buried by dust storms or in the sediments of the swollen of the warm interglacial ages, enable geologist to recognize deposits laid down in any one age.
On other evidence, geologists estimate the length of these ages in years and the whole epoch is believed by American authorities to have lasted a million years ending about twenty-five thousand years ago.
Very early in the Pleistocene primitive men were living in widely separated localities, probably migrants escaping competition with more progressive races at home.
The most primitive of these is the Trinil man (Pithecanthropus) of Java. He was very ape-like, but recent discoveries (1937) shown anatomical features that distinctively human.
There is however no evidence of distinctively human behavior. It is different with Peking man (Sinanthropus), who inhibited caves eastern China at about the same time.
He had larger brain, and he made tools and fire, - activities as distinctively human as articulate speech.
When he learned a kindle a fire from sparks that flew as he chipped flints to make his crude implements, he made the first application of a physical principle to human needs.
Perhaps earlier in time, but with more modern features the Piltdown man (Eoanthropus) was established in southeastern England in the Pliocene or earliest Pleistocene.
A somewhat later type, of Mid-Pleistocene age, the Neanderthal, pursing the great beasts, overran Europe during the second interglacial period. Around their camp fires they made the first completely flaked flint implement, the hand ax- tool characteristic of the Old Stone Age, Paleolithic.
They in turn, gave way during the last Ice Age, perhaps 150,000 years ago, to modern man Homo sapiens, represented by the Brunn and Co-Magnon races.
The latter left in numerous cave dwellings implements of flint and bone and drawing and sculptures, showing fine powers or observation and great manual dexterity.
The Antiquity and Ancestry of Man
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