A little over 2,200 years ago, the Roman navy attached 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 67 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 wetting 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 discusses the reasons why the burning mirror is an impractical weapon when fighting against the Romans. However, the professor in the lecture argues that the claims in the reading are unconvincing and that the burning mirror is definitely useful in a wartime situation.
The reading passage starts out with the claim that the burning mirror would be to technological advances for the ancient Greeks. The mirror would have to be several meters wide and have a very precise parabolic shape. Yet the professor disagrees with this assertion. He claims that a dozen of the individual flat and polished copper plate could be arranged in a parabolic formation to achieve the same result and the Greek philosophers at the time would have enough knowledge to set it up.
Another reason given by the reading is that it would take too long to ignite the warships. As an experiment showed, it would take 10 minutes for a device of such to set fire on wood at a distance of 30 meters. However, the lecturer explains that the ships are not completely made out of wood. The other materials, for example, the sticky pitch used to seal the boat, can be ignited by the device in a matter of seconds. These materials can then pass the fire to other parts of the boat.
The last explanation of the reading was that there was no motive for the burning mirrors to be created. It has about the same effect as the flaming arrows - something the Greek army already has and uses. Then again, the professor refutes this statement. He claims that the burning mirror attacks by surprise. As the Romans know about the flaming arrows, they pay special attention to them. However as the burning mirror is incorporeal, it is hard to prevent and therefore a lot more effective.
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- tpo40 73
- A little over 2,200 years ago, the Roman navy attached 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 80
- Do you agree or disagree with the following statements? Playing sports teaches people more lessons about the life. 71
- Do you agree or disagree with the following statement? The best way to travel is in a group led by a tour guide. Use specific reasons and examples to support your answer 70
- TPO-42 81
Grammar and spelling errors:
Line 7, column 391, Rule ID: SENT_START_CONJUNCTIVE_LINKING_ADVERB_COMMA[1]
Message: Did you forget a comma after a conjunctive/linking adverb?
Suggestion: However,
...ws, they pay special attention to them. However as the burning mirror is incorporeal, i...
^^^^^^^
Transition Words or Phrases used:
however, second, so, then, therefore, for example
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 14.0 10.4613686534 134% => OK
Auxiliary verbs: 8.0 5.04856512141 158% => OK
Conjunction : 7.0 7.30242825607 96% => OK
Relative clauses : 9.0 12.0772626932 75% => More relative clauses wanted.
Pronoun: 20.0 22.412803532 89% => OK
Preposition: 36.0 30.3222958057 119% => OK
Nominalization: 8.0 5.01324503311 160% => OK
Performance on vocabulary words:
No of characters: 1464.0 1373.03311258 107% => OK
No of words: 308.0 270.72406181 114% => OK
Chars per words: 4.75324675325 5.08290768461 94% => OK
Fourth root words length: 4.18926351222 4.04702891845 104% => OK
Word Length SD: 2.52175627705 2.5805825403 98% => OK
Unique words: 164.0 145.348785872 113% => OK
Unique words percentage: 0.532467532468 0.540411800872 99% => OK
syllable_count: 457.2 419.366225166 109% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 7.0 3.25607064018 215% => Less pronouns wanted as sentence beginning.
Article: 9.0 8.23620309051 109% => OK
Subordination: 2.0 1.25165562914 160% => OK
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: 17.0 13.0662251656 130% => OK
Sentence length: 18.0 21.2450331126 85% => The Avg. Sentence Length is relatively short.
Sentence length SD: 42.614632703 49.2860985944 86% => OK
Chars per sentence: 86.1176470588 110.228320801 78% => OK
Words per sentence: 18.1176470588 21.698381199 83% => OK
Discourse Markers: 2.88235294118 7.06452816374 41% => More transition words/phrases wanted.
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 : 7.0 4.45695364238 157% => OK
Sentences with neutral sentiment: 6.0 4.27373068433 140% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.123632266991 0.272083759551 45% => OK
Sentence topic coherence: 0.0383750787075 0.0996497079465 39% => Sentence topic similarity is low.
Sentence topic coherence SD: 0.0325712408963 0.0662205650399 49% => Sentences are similar to each other.
Paragraph topic coherence: 0.0767514647599 0.162205337803 47% => OK
Paragraph topic coherence SD: 0.0388800769225 0.0443174109184 88% => OK
Essay readability:
automated_readability_index: 10.0 13.3589403974 75% => Automated_readability_index is low.
flesch_reading_ease: 61.67 53.8541721854 115% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 9.1 11.0289183223 83% => OK
coleman_liau_index: 9.97 12.2367328918 81% => OK
dale_chall_readability_score: 8.07 8.42419426049 96% => OK
difficult_words: 69.0 63.6247240618 108% => OK
linsear_write_formula: 8.5 10.7273730684 79% => OK
gunning_fog: 9.2 10.498013245 88% => OK
text_standard: 10.0 11.2008830022 89% => OK
What are above readability scores?
---------------------
Rates: 80.0 out of 100
Scores by essay e-grader: 24.0 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.