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 discuss wheather the Greeks defended themselves with a weapon burning mirror. The former argues that there are several reasons to doubt that the burning mirror is just a myth, but the later contradicts each of these points.
First of all, the author of the passage claims that ancient Greeeks were not that much technologically forward enough to make such device. However, the listening contends that there were improved technology in the past since a Greek mathematician had colleced small mirrors and made it several meters wide in a exact parabolic shape which was capable of producing enough intensity of sunlight to set ships on fire.
Second of all, the writer of the passage contends that burning mirror would have taken long time to set the fire on ships. Nonetheless, the lecturer asserts that the ships were made of sticky pitch material frontly which catches fire with in a second and it later quicky spread on wood which was the main material for ships construction.
Third of all, the author of the passage argue that ancient Greeks had already flaming arrows and a burning mirror does not seem like enhancement on it, so Greeks had no reason to buid a weapon like a burning mirror. Notwithstanding, the audio underlines that unlike flaming arrow which focuse of a particular place of the ship, burning mirror sets fire on unobserved place of the ship. So burning mirror was more effective weapon.
Grammar and spelling errors:
Line 3, column 310, Rule ID: EN_A_VS_AN
Message: Use 'an' instead of 'a' if the following word starts with a vowel sound, e.g. 'an article', 'an hour'
Suggestion: an
...rors and made it several meters wide in a exact parabolic shape which was capable...
^
Transition Words or Phrases used:
but, first, however, nonetheless, second, so, third, first of all
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 8.0 10.4613686534 76% => OK
Auxiliary verbs: 1.0 5.04856512141 20% => OK
Conjunction : 5.0 7.30242825607 68% => OK
Relative clauses : 13.0 12.0772626932 108% => OK
Pronoun: 14.0 22.412803532 62% => OK
Preposition: 32.0 30.3222958057 106% => 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: 1218.0 1373.03311258 89% => OK
No of words: 245.0 270.72406181 90% => More content wanted.
Chars per words: 4.97142857143 5.08290768461 98% => OK
Fourth root words length: 3.95632099841 4.04702891845 98% => OK
Word Length SD: 2.53910359452 2.5805825403 98% => OK
Unique words: 133.0 145.348785872 92% => More unique words wanted.
Unique words percentage: 0.542857142857 0.540411800872 100% => OK
syllable_count: 369.0 419.366225166 88% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 0.0 3.25607064018 0% => OK
Article: 7.0 8.23620309051 85% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 1.0 1.51434878587 66% => OK
Preposition: 0.0 2.5761589404 0% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 9.0 13.0662251656 69% => Need more sentences. Double check the format of sentences, make sure there is a space between two sentences, or have enough periods. And also check the lengths of sentences, maybe they are too long.
Sentence length: 27.0 21.2450331126 127% => The Avg. Sentence Length is relatively long.
Sentence length SD: 63.6444599628 49.2860985944 129% => OK
Chars per sentence: 135.333333333 110.228320801 123% => OK
Words per sentence: 27.2222222222 21.698381199 125% => OK
Discourse Markers: 7.22222222222 7.06452816374 102% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 2.0 4.33554083885 46% => More positive sentences wanted.
Sentences with negative sentiment : 6.0 4.45695364238 135% => OK
Sentences with neutral sentiment: 1.0 4.27373068433 23% => More facts, knowledge or examples wanted.
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.172668022506 0.272083759551 63% => OK
Sentence topic coherence: 0.0849793577943 0.0996497079465 85% => OK
Sentence topic coherence SD: 0.0712552389451 0.0662205650399 108% => OK
Paragraph topic coherence: 0.112820443634 0.162205337803 70% => OK
Paragraph topic coherence SD: 0.0687374829922 0.0443174109184 155% => OK
Essay readability:
automated_readability_index: 15.6 13.3589403974 117% => OK
flesch_reading_ease: 52.53 53.8541721854 98% => OK
smog_index: 8.8 5.55761589404 158% => OK
flesch_kincaid_grade: 12.6 11.0289183223 114% => OK
coleman_liau_index: 11.84 12.2367328918 97% => OK
dale_chall_readability_score: 8.2 8.42419426049 97% => OK
difficult_words: 50.0 63.6247240618 79% => More difficult words wanted.
linsear_write_formula: 13.5 10.7273730684 126% => OK
gunning_fog: 12.8 10.498013245 122% => OK
text_standard: 13.0 11.2008830022 116% => OK
What are above readability scores?
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Rates: 85.0 out of 100
Scores by essay e-grader: 25.5 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.