A little over 2,200 years ago, the Roman navy attacked the Greek port city of Syracuse. According to some ancient historians, the Greeks defended themselves with an ingenious weapon called a “burning mirror”: a polished copper surface curved to focus the Sun’s rays onto Roman ships, causing them to catch fire. However, we have several reasons to suspect that the story of the burning mirror is just a myth and the Greeks of Syracuse never really built such a device.
First, the ancient Greeks were not technologically advanced enough to make such a device. A mirror that would focus sunlight with sufficient intensity to set ships on fire would have to be several meters wide. Moreover, the mirror would have to have a very precise parabolic curvature (a curvature derived from a geometric shape known as the parabola). The technology for manufacturing a large sheet of copper with such specifications did not exist in the ancient world.
Second, the burning mirror would have taken a long time to set the ships on fire. In an experiment conducted to determine whether a burning mirror was feasible, a device concentrating the Sun’s rays on a wooden object 30 meters away took ten minutes to set the object on fire; and during that time, the object had to be unmoving. It is unlikely that the Roman ships stayed perfectly still for that much time. Such a weapon would therefore have been very impractical and ineffective.
Third, a burning mirror does not seem like an improvement on a weapon that the Greeks already had: flaming arrows. Shooting at an enemy’s ships with flaming arrows was a common way of setting the ships on fire. The burning mirror and flaming arrows would have been effective at about the same distance. So the Greeks had no reason to build a weapon like a burning mirror.
The passage and the lecture are both about a wapon called burning mirror that ancient Greeks used as a defence against Roman ships. The author of the reading believes that the burning mirror seems to be a mith story and Greeks can't biuilt this specific weapon. The lecturer cast doubts on the claims made in the article. She thinks that this reasons are unconvincing, and Greeks are able to built burning mirror.
First of all, the reading stats that Greeks didn't have technological advances to build such a huge mirror, which had precise parabolic curvature. Nevertheless, this specific argument is challenged by the lecturer. She says that Greeks used small flat pace of mirrors to built large parabolic curvature mirrors. The professor states that mathematician of Greek knew about using small mirrors, thus they were able to made this weapon.
Secondly, the passage claims that using burning mirror to set Rman ships on fire need a long time, and for wooden object 30 meters away took ten minutes to set the wood on fire. However, this argument rebutted in the lecture. The professor mentions that although ten minutes is needed for burning a wood, the Roman ships had a sticky waterproof material. She says experiment shows that this specific material can be burn with burning mirror in a second and spread in the ship and makes fire more quickly.
Finally, the author mentions that Greeks already had a weapon called flaming arrows, so whay should use another weapon. The professor casts doubt oby arguing that Romans were fimiliar with flaming arrows and could perevent burning bof arrows. Moreover, using of burning mirror was better way to make fire because romans were not able to see the fire a, and fire made by mirror was surprisingly for Romans.
In sum, all the three reasons mentioned in the reading are effectively challenged by the professor.
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- A little over 2 200 years ago the Roman navy attacked the Greek port city of Syracuse According to some ancient historians the Greeks defended themselves with an ingenious weapon called a burning mirror a polished copper surface curved to focus the Sun s 81
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Grammar and spelling errors:
Line 1, column 228, Rule ID: CANT[1]
Message: Did you mean 'can't' or 'cannot'?
Suggestion: can't; cannot
...ror seems to be a mith story and Greeks cant biuilt this specific weapon. The lectur...
^^^^
Line 1, column 262, Rule ID: ENGLISH_WORD_REPEAT_BEGINNING_RULE
Message: Three successive sentences begin with the same word. Reword the sentence or use a thesaurus to find a synonym.
...reeks cant biuilt this specific weapon. The lecturer cast doubts on the claims made...
^^^
Line 3, column 45, Rule ID: EN_CONTRACTION_SPELLING
Message: Possible spelling mistake found
Suggestion: didn't
...t of all, the reading stats that Greeks didnt have technological advances to build su...
^^^^^
Line 7, column 351, Rule ID: THE_PUNCT[1]
Message: Did you forget something after 'a'?
...se romans were not able to see the fire a, and fire made by mirror was surprisingl...
^^
Transition Words or Phrases used:
but, finally, first, however, if, moreover, nevertheless, second, secondly, so, thus, first of all
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 13.0 10.4613686534 124% => OK
Auxiliary verbs: 4.0 5.04856512141 79% => OK
Conjunction : 8.0 7.30242825607 110% => OK
Relative clauses : 12.0 12.0772626932 99% => OK
Pronoun: 21.0 22.412803532 94% => OK
Preposition: 31.0 30.3222958057 102% => OK
Nominalization: 4.0 5.01324503311 80% => OK
Performance on vocabulary words:
No of characters: 1560.0 1373.03311258 114% => OK
No of words: 313.0 270.72406181 116% => OK
Chars per words: 4.98402555911 5.08290768461 98% => OK
Fourth root words length: 4.20616286096 4.04702891845 104% => OK
Word Length SD: 2.39247425919 2.5805825403 93% => OK
Unique words: 169.0 145.348785872 116% => OK
Unique words percentage: 0.539936102236 0.540411800872 100% => OK
syllable_count: 468.0 419.366225166 112% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 5.0 3.25607064018 154% => OK
Article: 10.0 8.23620309051 121% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 3.0 1.51434878587 198% => OK
Preposition: 1.0 2.5761589404 39% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 16.0 13.0662251656 122% => OK
Sentence length: 19.0 21.2450331126 89% => OK
Sentence length SD: 35.4091597436 49.2860985944 72% => OK
Chars per sentence: 97.5 110.228320801 88% => OK
Words per sentence: 19.5625 21.698381199 90% => OK
Discourse Markers: 6.125 7.06452816374 87% => OK
Paragraphs: 5.0 4.09492273731 122% => OK
Language errors: 4.0 4.19205298013 95% => OK
Sentences with positive sentiment : 3.0 4.33554083885 69% => OK
Sentences with negative sentiment : 10.0 4.45695364238 224% => Less negative sentences wanted.
Sentences with neutral sentiment: 3.0 4.27373068433 70% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.185035259051 0.272083759551 68% => OK
Sentence topic coherence: 0.0667151553366 0.0996497079465 67% => OK
Sentence topic coherence SD: 0.0523580809043 0.0662205650399 79% => OK
Paragraph topic coherence: 0.103787587668 0.162205337803 64% => OK
Paragraph topic coherence SD: 0.0683599739257 0.0443174109184 154% => OK
Essay readability:
automated_readability_index: 11.8 13.3589403974 88% => Automated_readability_index is low.
flesch_reading_ease: 60.65 53.8541721854 113% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 9.5 11.0289183223 86% => OK
coleman_liau_index: 11.6 12.2367328918 95% => OK
dale_chall_readability_score: 7.91 8.42419426049 94% => OK
difficult_words: 66.0 63.6247240618 104% => OK
linsear_write_formula: 8.0 10.7273730684 75% => OK
gunning_fog: 9.6 10.498013245 91% => OK
text_standard: 8.0 11.2008830022 71% => OK
What are above readability scores?
---------------------
Rates: 81.6666666667 out of 100
Scores by essay e-grader: 24.5 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.