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.
Both the reading passage and the listening material discuss the authenticity that the Greeks of Syracuse did ever build a weapon called a burning mirror. The author claims that it is just a myth and provides three supporting arguments. However, the lecturer refutes all the writer's reasons, saying they are unconvincing.
First, the author argues that it was technologically impossible for the Ancient Greeks to make such a mirror from a single sheet of copper. Yet, the professor affirms that an experiment shows that small pieces of polished copper can form a large burning mirror. The Greek mathematicians were clever enough to direct the assembly of burning mirrors correctly.
Second, the author claims that an experiment proves that a mirror takes a long time to set a fire on a wooden object, and it has to be unmoving, which makes the burning mirror an ineffective weapon for the Roman ships. Nevertheless, the professor points out that those ancient ships did not consist of just wood. She clarifies that builders of ships used a sticky material called a pitch to hold the wood pieces together, and the pitch catches fire quickly. Thus the burning mirror can set the pitch on fire first, then ships. Therefore, the burning mirror was an effective weapon.
Third, the author states that the Greeks used flaming arrows to set fires on the enemy's ships. So, why bother and build a new weapon as the burning mirror with the same effectiveness. In contrast, the professor asserts that the Roman soldiers were familiar with the flaming arrows and can see them. So, they can set off the fire and protect their ships. On the other hand, Roman soldiers cannot see the burning mirror, they can only see the mirror, and the fire took them by surprise in any place in their ships. Thus, the burning mirrors are more effective as weapons than flaming arrows.
Grammar and spelling errors:
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Both the reading passage and the listeni...
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...reasons, saying they are unconvincing. First, the author argues that it was tec...
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Line 3, column 1, Rule ID: WHITESPACE_RULE
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...ssembly of burning mirrors correctly. Second, the author claims that an experi...
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Suggestion: Thus,
...er, and the pitch catches fire quickly. Thus the burning mirror can set the pitch on...
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Suggestion:
...burning mirror was an effective weapon. Third, the author states that the Greeks...
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Transition Words or Phrases used:
first, however, if, nevertheless, second, so, then, therefore, third, thus, as to, in contrast, on the other hand
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 8.0 10.4613686534 76% => OK
Auxiliary verbs: 6.0 5.04856512141 119% => OK
Conjunction : 8.0 7.30242825607 110% => OK
Relative clauses : 12.0 12.0772626932 99% => OK
Pronoun: 23.0 22.412803532 103% => OK
Preposition: 26.0 30.3222958057 86% => OK
Nominalization: 2.0 5.01324503311 40% => More nominalizations (nouns with a suffix like: tion ment ence ance) wanted.
Performance on vocabulary words:
No of characters: 1542.0 1373.03311258 112% => OK
No of words: 316.0 270.72406181 117% => OK
Chars per words: 4.87974683544 5.08290768461 96% => OK
Fourth root words length: 4.21620550194 4.04702891845 104% => OK
Word Length SD: 2.49040781173 2.5805825403 97% => OK
Unique words: 160.0 145.348785872 110% => OK
Unique words percentage: 0.506329113924 0.540411800872 94% => More unique words wanted or less content wanted.
syllable_count: 456.3 419.366225166 109% => OK
avg_syllables_per_word: 1.4 1.55342163355 90% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 3.0 3.25607064018 92% => OK
Article: 11.0 8.23620309051 134% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 3.0 1.51434878587 198% => OK
Preposition: 2.0 2.5761589404 78% => OK
Performance on sentences:
How many sentences: 17.0 13.0662251656 130% => OK
Sentence length: 18.0 21.2450331126 85% => The Avg. Sentence Length is relatively short.
Sentence length SD: 41.8772303543 49.2860985944 85% => OK
Chars per sentence: 90.7058823529 110.228320801 82% => OK
Words per sentence: 18.5882352941 21.698381199 86% => OK
Discourse Markers: 6.64705882353 7.06452816374 94% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 5.0 4.19205298013 119% => OK
Sentences with positive sentiment : 6.0 4.33554083885 138% => OK
Sentences with negative sentiment : 6.0 4.45695364238 135% => OK
Sentences with neutral sentiment: 5.0 4.27373068433 117% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.224704746373 0.272083759551 83% => OK
Sentence topic coherence: 0.0791516499848 0.0996497079465 79% => OK
Sentence topic coherence SD: 0.0563699093138 0.0662205650399 85% => OK
Paragraph topic coherence: 0.147346336021 0.162205337803 91% => OK
Paragraph topic coherence SD: 0.0340842536288 0.0443174109184 77% => OK
Essay readability:
automated_readability_index: 10.8 13.3589403974 81% => Automated_readability_index is low.
flesch_reading_ease: 70.13 53.8541721854 130% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 7.9 11.0289183223 72% => OK
coleman_liau_index: 11.02 12.2367328918 90% => OK
dale_chall_readability_score: 7.68 8.42419426049 91% => OK
difficult_words: 63.0 63.6247240618 99% => OK
linsear_write_formula: 8.5 10.7273730684 79% => OK
gunning_fog: 9.2 10.498013245 88% => OK
text_standard: 8.0 11.2008830022 71% => OK
What are above readability scores?
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Rates: 65.0 out of 100
Scores by essay e-grader: 19.5 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.