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 rally 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.
In the reading passage, the author concentrates on several reasons to suspect that the Greeks of Syracuse could never build an ingenious weapon called a "burning mirror" to defend themselves against the Roman navy. However, the lecturer casts doubt on these reasons and respectively points out the problems with all author's assertions.
Firstly, the author argues that the technology was not developed enough to build such a precise device in ancient Greece. By contrast, the lecturer challenges this idea and states that ancient Greeks could make a lot of small flat copper pieces and then attach them together to form a parabolic shape.
Secondly, according to an experiment, the author suggests that it takes about 10 minutes to set the ships on fire by such a burning mirror, and it is impossible for Roman ships to stay perfectly still during this period of time. Nevertheless, the lecturer brings up the fact that the mentioned experiment used wooden material as a sample to test. However, Romans have also used other materials in addition to wood when building their ships. For example, they have employed a special substance called pitch to make the ship waterproof. With such a material, the ships took a very shorter period of time, about several seconds, to start to burn.
Thirdly, the author asserts that while having flaming arrows, which were quite effective at the same distance, it is unlikely that ancient Greeks used burning mirrors in the war. Conversely, the lecturer refutes this claim and clarifies that Romans were aware of the possible use of flaming arrows, so they could watch them carefully. However, the more surprising the use of a new weapon, like a burning mirror, seemed, the effective and destructive it was to set the ships on fire.
Grammar and spelling errors:
Line 1, column 152, 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
... never build an ingenious weapon called a 'burning mirror' to defend th...
^
Line 3, column 214, Rule ID: PERIOD_OF_TIME[1]
Message: Use simply 'period'.
Suggestion: period
...ips to stay perfectly still during this period of time. Nevertheless, the lecturer brings up t...
^^^^^^^^^^^^^^
Line 3, column 588, Rule ID: PERIOD_OF_TIME[1]
Message: Use simply 'period'.
Suggestion: period
...material, the ships took a very shorter period of time, about several seconds, to start to bur...
^^^^^^^^^^^^^^
Transition Words or Phrases used:
also, conversely, first, firstly, however, if, nevertheless, second, secondly, so, still, then, third, thirdly, while, as to, for example, in addition
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 6.0 10.4613686534 57% => More to be verbs wanted.
Auxiliary verbs: 3.0 5.04856512141 59% => OK
Conjunction : 6.0 7.30242825607 82% => OK
Relative clauses : 10.0 12.0772626932 83% => OK
Pronoun: 22.0 22.412803532 98% => OK
Preposition: 40.0 30.3222958057 132% => OK
Nominalization: 5.0 5.01324503311 100% => OK
Performance on vocabulary words:
No of characters: 1487.0 1373.03311258 108% => OK
No of words: 294.0 270.72406181 109% => OK
Chars per words: 5.05782312925 5.08290768461 100% => OK
Fourth root words length: 4.14082457966 4.04702891845 102% => OK
Word Length SD: 2.60988990005 2.5805825403 101% => OK
Unique words: 171.0 145.348785872 118% => OK
Unique words percentage: 0.581632653061 0.540411800872 108% => OK
syllable_count: 454.5 419.366225166 108% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 2.0 3.25607064018 61% => OK
Article: 11.0 8.23620309051 134% => OK
Subordination: 0.0 1.25165562914 0% => More adverbial clause wanted.
Conjunction: 1.0 1.51434878587 66% => OK
Preposition: 8.0 2.5761589404 311% => Less preposition wanted as sentence beginnings.
Performance on sentences:
How many sentences: 12.0 13.0662251656 92% => OK
Sentence length: 24.0 21.2450331126 113% => OK
Sentence length SD: 44.9044510291 49.2860985944 91% => OK
Chars per sentence: 123.916666667 110.228320801 112% => OK
Words per sentence: 24.5 21.698381199 113% => OK
Discourse Markers: 12.5 7.06452816374 177% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 3.0 4.19205298013 72% => OK
Sentences with positive sentiment : 4.0 4.33554083885 92% => OK
Sentences with negative sentiment : 5.0 4.45695364238 112% => OK
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: 0.189553617533 0.272083759551 70% => OK
Sentence topic coherence: 0.0635174312214 0.0996497079465 64% => OK
Sentence topic coherence SD: 0.0645603012486 0.0662205650399 97% => OK
Paragraph topic coherence: 0.116152909863 0.162205337803 72% => OK
Paragraph topic coherence SD: 0.0516185364938 0.0443174109184 116% => OK
Essay readability:
automated_readability_index: 14.7 13.3589403974 110% => OK
flesch_reading_ease: 55.58 53.8541721854 103% => OK
smog_index: 8.8 5.55761589404 158% => OK
flesch_kincaid_grade: 11.5 11.0289183223 104% => OK
coleman_liau_index: 12.36 12.2367328918 101% => OK
dale_chall_readability_score: 8.8 8.42419426049 104% => OK
difficult_words: 74.0 63.6247240618 116% => OK
linsear_write_formula: 14.5 10.7273730684 135% => OK
gunning_fog: 11.6 10.498013245 110% => OK
text_standard: 12.0 11.2008830022 107% => OK
What are above readability scores?
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Rates: 80 out of 100
Scores by essay e-grader: 24 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.