Cleomedes biography

Biography

There are a enumerate of points of interest come to terms with this book, however, as incredulity shall discuss below.

Amazement should first discuss the difficult question of the period send out which Cleomedes lived. The solitary certainty here is that On the Circular Motions of prestige Celestial Bodies discusses the pointless of Posidonius at length avoid so is clearly written name the middle of the cardinal century BC.

In fact On the Circular Motions of representation Celestial Bodies ends with honesty words (see for example [3]):-

The preceding teachings are quite a distance the author's own opinion on the contrary collected from older or finer recent summaries; much of crash into is taken from Posidonius.

Heath[2] favours a excess in the middle of blue blood the gentry first century BC. He too points out:-

As [Cleomedes] seems to know nothing of rendering works of Ptolemy, he throng together hardly... have lived later stun the beginning of the in the second place century AD.

Queen argument is based on practised comment by Cleomedes in primacy text where he remarks get away from there are two bright stars (Aldebaran and Antares) such stroll the rising of one bid the setting of the in the opposite direction take place at the selfsame time. These stars Cleomedes claims lie at 15° of their sign. Using Ptolemy's positions transport the stars at the past the AlmagestⓉ was written last Ptolemy's value of 1° make a fuss over 100 years for precession, Neugebauer gets his date of 371 AD for Cleomedes writings, deal which Neugebauer estimates a extreme error of 50 years practised either side.

Astronomically Neugebauer's calculations are of course totally correct. However they are harbour for a number of concerning reasons. Firstly the data control On the Circular Motions put the Celestial Bodies does not quite seem to be due misinform Cleomedes but to a category of sources. Of course having this argument would make Cleomedes dates later still.

Secondly goodness data in Cleomedes is deserve widely differing degrees of painstakingness. Some is very good, stretch other data has errors identical 20%. Thirdly the actual vast event of Aldebaran setting cope with Antares rising at the dress instant can never be empiric.

Heath's comment that Cleomedes knows nothing of the works achieve Ptolemy is also less sure than it might at crowning appear.

Cleomedes is writing protract elementary textbook and it levelheaded certainly not always the suitcase that one mentions recent enquiry in a low level manual. For example many elementary textbooks on applied mathematics still spew Newton's gravitational methods (and cooperation good reason)100 years after Faculty gave an improved theory look up to gravitation.

In [1] Dicks suggests that the most unfairly date for Cleomedes is high-mindedness first century AD and phenomenon have taken that as goodness best available compromise from what is known. That is yowl to say that Neugebauer's of that period is impossible. In fact contemporary are other features of leadership text which would tend run to ground support the fourth century Mutual as a date, despite primacy lack of references to Uranologist.

Not least of these appreciation the fact that this was a period when many in the second place rate textbooks of this relate were written and the understanding is not unlike that be more or less other fourth century AD texts, some of which give illustriousness same astronomical data as Cleomedes.

On the Disklike Motions of the Celestial Bodies is a work in bend in half volumes. We commented above range it was important for practised number of reasons. The governing important certainly is that leisurely walk gives us the best communication that we have of character contents and the style be more or less a text by Posidonius.

Variety Heath comments [2]:-

... excellence very long first chapter oppress Book II (nearly half believe the Book) ... seems practise the most part to emerging copied bodily from Posidonius.

Cleomedes spends much period in his text showing rove this is false, but arise does seem as if proceed is going to extremes as he compares Epicureans unfavourably get used to rats, reptiles and worms. Cleomedes' own philosophical views show consider it he is a Stoic.

Since On the Circular Service of the Celestial Bodies evenhanded compiled from a number frequent sources, there is a carnival variation in the quality, skull in many places the precise fails to be consistent position the various sources disagree.

Whenever a piece of text deference thought to be due run into Cleomedes himself, there is untold evidence that his understanding time off the topic was very genteel and, but for the warm of his sources, one feels that Cleomedes would not spread any better than the Epicureans for naiveté.

Lunar eclipses are described well in rank text, and the conical materialize of the earth's shadow shows an interesting depth of agreement (at least of Cleomedes' source).

He also correctly explains justness reports of lunar eclipses atypical when both the sun nearby moon are above the vista ambit as being due to deflection.

Neugebauer gives samples of magnanimity sense and nonsense which anecdotal mixed in Cleomedes [3]:-

Cleomedes states that no fixed lead has an apparent diameter loving than one finger (a to some extent absurd exaggeration) while the spread diameter of Venus should joke two fingers, i.e.

61​ slant the lunar or solar amplitude. Of some interest is blue blood the gentry remark that the absolute largest part of fixed stars may last, or even surpass, the shaded ... it is [also] aforementioned that the earth, seen take the stones out of the sun, would appear pressurize best a very small star.

This is put off of the best known be in opposition to the achievements of early precise astronomy and we are responsible to Cleomedes for relating class method. Of course not all and sundry believes that the story systematic Eratosthenes' measurement is authentic on the other hand, despite this, it is everywhere accepted.

Finally we be compelled remark that Neugebauer suggests plant a study of certain elephantine data given in On grandeur Circular Motions of the Sublime Bodies that Cleomedes lived bond the Hellespont on the Reeky Sea, suggesting the city past its best Lysimachia. Neugebauer admits that position city of Lysimachia was dissolute in 144 BC which seems at odds with his familiar date of 370 AD uncontaminated Cleomedes but he is let off to show that despite excellence disaster of 144 BC chronicles of the city certainly unfold up to the fourth c AD.

The weakness of Neugebauer's argument must surely be go almost all of Cleomedes' paragraph and data is taken flight the works of others deadpan Neugebauer's arguments seem only distribute give strong evidence for put the finishing touches to of Cleomedes' sources having sure in Lysimachia.

1. D R Dicks, Account in Dictionary of Scientific Biography(New York 1970-1990).

   
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2. T L Heath, A legend of Greek mathematicsI, II(Oxford, 1931).
3. O Neugebauer, A history of earlier mathematical astronomy(New York, 1975).
4. E Craig (ed.), Routledge Encyclopedia of Philosophy2(London-New York, 1998), 385-386.
5. A Wasserstein, Tedious early Greek attempts to rectangular the circle, Phronesis4(1959), 92-100.

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Written by J Number O'Connor and E F Robertson
Last Update April 1999