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 reading passage and the professor offer opposing views regarding the myth of burning mirrors as a weapon. While the author of the passage presents three possible facts to refute the myth, the lecture thinks the cases of the texts are unconvincing.
Firstly, the author of the reading suggests that ancient Greeks were not that much technically sound to build such mirror. The reading states that they would need to build a large mirror of parabolic curvature which was not possible at that time. The lecture argues against in that point with the reading as it was possible to arrange dozens of small mirrors to build such a big mirror. Moreover he mentions that the mathematicians of that time had the formula to build mirror of parabolic shape, which helped Greeks to build such a mirror.
Secondly, the reading passage states the time required to set the ships on fire. It points out that it was not virtually possible to set the ships on fire as the ships were in motion. However, the professor in the lecture believes that in order to make the boats waterproof, people at that time used pitch which is highly flammable. He mentions an experiment which has proved that it takes only a second to set fire on pitch, and he claims that those pitches were capable enough to burn the wood of the boats.
Finally, the professor refutes the idea of the passage that mirror was not superior as a weapon than flaming arrows. He explains that flaming arrow was a common weapon back then, and hence roman soldiers were familiar to it. According to him, mirrors were more effective than arrows as they were able to surprise the romans, who were not expecting that kind of attack from their enemy.
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Grammar and spelling errors:
Line 1, column 253, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
...he cases of the texts are unconvincing. Firstly, the author of the reading sugge...
^^^
Line 2, column 388, Rule ID: SENT_START_CONJUNCTIVE_LINKING_ADVERB_COMMA[1]
Message: Did you forget a comma after a conjunctive/linking adverb?
Suggestion: Moreover,
...all mirrors to build such a big mirror. Moreover he mentions that the mathematicians of ...
^^^^^^^^
Transition Words or Phrases used:
finally, first, firstly, hence, however, moreover, regarding, second, secondly, so, then, while, kind of
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 14.0 10.4613686534 134% => OK
Auxiliary verbs: 2.0 5.04856512141 40% => OK
Conjunction : 3.0 7.30242825607 41% => More conjunction wanted.
Relative clauses : 20.0 12.0772626932 166% => OK
Pronoun: 29.0 22.412803532 129% => Less pronouns wanted
Preposition: 40.0 30.3222958057 132% => OK
Nominalization: 1.0 5.01324503311 20% => More nominalizations (nouns with a suffix like: tion ment ence ance) wanted.
Performance on vocabulary words:
No of characters: 1400.0 1373.03311258 102% => OK
No of words: 297.0 270.72406181 110% => OK
Chars per words: 4.7138047138 5.08290768461 93% => OK
Fourth root words length: 4.15134772569 4.04702891845 103% => OK
Word Length SD: 2.31513741248 2.5805825403 90% => OK
Unique words: 147.0 145.348785872 101% => OK
Unique words percentage: 0.494949494949 0.540411800872 92% => More unique words wanted or less content wanted.
syllable_count: 426.6 419.366225166 102% => 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: 8.0 8.23620309051 97% => OK
Subordination: 1.0 1.25165562914 80% => OK
Conjunction: 2.0 1.51434878587 132% => OK
Preposition: 1.0 2.5761589404 39% => More preposition wanted as sentence beginning.
Performance on sentences:
How many sentences: 13.0 13.0662251656 99% => OK
Sentence length: 22.0 21.2450331126 104% => OK
Sentence length SD: 25.7486714772 49.2860985944 52% => The essay contains lots of sentences with the similar length. More sentence varieties wanted.
Chars per sentence: 107.692307692 110.228320801 98% => OK
Words per sentence: 22.8461538462 21.698381199 105% => OK
Discourse Markers: 8.0 7.06452816374 113% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 2.0 4.19205298013 48% => OK
Sentences with positive sentiment : 1.0 4.33554083885 23% => More positive sentences wanted.
Sentences with negative sentiment : 7.0 4.45695364238 157% => 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: 0.108979638829 0.272083759551 40% => OK
Sentence topic coherence: 0.0427198299423 0.0996497079465 43% => OK
Sentence topic coherence SD: 0.0354063177171 0.0662205650399 53% => OK
Paragraph topic coherence: 0.0624069258991 0.162205337803 38% => Maybe some paragraphs are off the topic.
Paragraph topic coherence SD: 0.0312455074874 0.0443174109184 71% => OK
Essay readability:
automated_readability_index: 12.2 13.3589403974 91% => Automated_readability_index is low.
flesch_reading_ease: 66.07 53.8541721854 123% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 9.5 11.0289183223 86% => OK
coleman_liau_index: 10.33 12.2367328918 84% => OK
dale_chall_readability_score: 7.81 8.42419426049 93% => OK
difficult_words: 58.0 63.6247240618 91% => OK
linsear_write_formula: 10.5 10.7273730684 98% => OK
gunning_fog: 10.8 10.498013245 103% => OK
text_standard: 11.0 11.2008830022 98% => OK
What are above readability scores?
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Rates: 73.3333333333 out of 100
Scores by essay e-grader: 22.0 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.