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 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 has expressed some reason to support that the burning mirror is just a myth, and the Greeks never built such a device. However, the professor said in the lecture that none of those reasons are convincing, and the Greeks could have the burning mirror.
First, the passage has claimed that the burning mirror has to be several meters wide, and the Greeks had not technology to build it. In contrast, the professor said that the Greeks could build the burning mirror by assembling many small pieces of mirror and being parabolic.
Second, the passage has asserted that it takes a long time to set a ship on fire using the burning mirror, and the ship has to be unmoving. On the contrary, the professor explained that the passage's claim is true in the case of wood, but the Romans had other materials, sticky substances, such as pitch that can burn quickly even if the ship is moving.
Third, the passage has alleged that the Greeks had flaming arrows, and they did not have to build a burning mirror. In contrast, the professor mentioned that Romans were familiar with the flaming arrows, and they could put them off the ship, but they could just see the mirror and do nothing about it. So, the burning mirror was more effective.
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Grammar and spelling errors:
Line 4, column 345, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
... the burning mirror was more effective.
^^
Transition Words or Phrases used:
but, first, however, if, second, so, third, as to, in contrast, such as, on the contrary
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 9.0 10.4613686534 86% => OK
Auxiliary verbs: 5.0 5.04856512141 99% => OK
Conjunction : 10.0 7.30242825607 137% => OK
Relative clauses : 9.0 12.0772626932 75% => More relative clauses wanted.
Pronoun: 17.0 22.412803532 76% => OK
Preposition: 19.0 30.3222958057 63% => OK
Nominalization: 0.0 5.01324503311 0% => More nominalizations (nouns with a suffix like: tion ment ence ance) wanted.
Performance on vocabulary words:
No of characters: 1022.0 1373.03311258 74% => OK
No of words: 220.0 270.72406181 81% => More content wanted.
Chars per words: 4.64545454545 5.08290768461 91% => OK
Fourth root words length: 3.85128510684 4.04702891845 95% => OK
Word Length SD: 2.23396027547 2.5805825403 87% => OK
Unique words: 110.0 145.348785872 76% => More unique words wanted.
Unique words percentage: 0.5 0.540411800872 93% => More unique words wanted or less content wanted.
syllable_count: 299.7 419.366225166 71% => OK
avg_syllables_per_word: 1.4 1.55342163355 90% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 0.0 3.25607064018 0% => OK
Article: 9.0 8.23620309051 109% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 8.0 1.51434878587 528% => Less conjunction wanted as sentence beginning.
Preposition: 3.0 2.5761589404 116% => OK
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: 24.0 21.2450331126 113% => OK
Sentence length SD: 44.1764140187 49.2860985944 90% => OK
Chars per sentence: 113.555555556 110.228320801 103% => OK
Words per sentence: 24.4444444444 21.698381199 113% => OK
Discourse Markers: 9.77777777778 7.06452816374 138% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 4.0 4.33554083885 92% => OK
Sentences with negative sentiment : 1.0 4.45695364238 22% => More negative sentences wanted.
Sentences with neutral sentiment: 4.0 4.27373068433 94% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.166912881312 0.272083759551 61% => OK
Sentence topic coherence: 0.0870191816853 0.0996497079465 87% => OK
Sentence topic coherence SD: 0.0329621077978 0.0662205650399 50% => Sentences are similar to each other.
Paragraph topic coherence: 0.114677378951 0.162205337803 71% => OK
Paragraph topic coherence SD: 0.0384182017868 0.0443174109184 87% => OK
Essay readability:
automated_readability_index: 12.7 13.3589403974 95% => OK
flesch_reading_ease: 64.04 53.8541721854 119% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 10.3 11.0289183223 93% => OK
coleman_liau_index: 9.99 12.2367328918 82% => OK
dale_chall_readability_score: 7.48 8.42419426049 89% => OK
difficult_words: 37.0 63.6247240618 58% => More difficult words wanted.
linsear_write_formula: 10.5 10.7273730684 98% => OK
gunning_fog: 11.6 10.498013245 110% => OK
text_standard: 11.0 11.2008830022 98% => OK
What are above readability scores?
---------------------
Rates: 63.3333333333 out of 100
Scores by essay e-grader: 19.0 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.