這段敘述出處:
http://d29qn7q9z0j1p6.cloudfront.net/content/371/1986/20110568
正在看一篇E. A Wrigley寫能源與工業革命的文章，
這邊作者引用的文字我一直看不懂，
翻譯感覺比較能理解文章，但這串文字不知道是否有理解錯誤的地方，
希望能請版上大大指點迷津!!! 謝謝~~~~~
我的試譯:
A coal miner who consumes in his own body about 3,500 calories a day, will,
if he mines 500 pounds of coal, produce coal with a heat value of 500 times
the heat value of his food which he consumed while mining it.
一名每日消耗3500卡路里熱量的煤礦工人，假設他開採500鎊的煤炭，其產出的煤炭熱值
是開採時所消耗之食物熱值的500倍。
At 20 percent efficiency, he expends about 1 horsepower of mechanical energy
to get the coal.
在效率20%的情況下，他開採煤炭所消耗的機械能約1馬力。
Now if the coal he mines is burned in a steam engine of even 1 percent
efficiency, it will yield about 27 horsepower-hours of mechanical energy.
現在，如果他開採的煤炭，經效率僅1%的蒸汽機燃燒後，將能產出27馬力時（
horsepower-hours）的機械能。
（這裡的馬力時可以理解成每小時27馬力嗎？）
The surplus of mechanical energy gained would thus be 26 horsepower-hours, or
the equivalent of 26 man- days per man-day.
扣掉該人一天消耗的機械能後，所剩餘的機械能約26馬力時，或者相當於26人一天所生產
的能量。
A coal miner who consumed about one-fifth as much food as a horse, could thus
deliver through the steam engine about four times the mechanical energy which
the average horse in Watt’s day was found to deliver.
一個煤礦工人大約可以消耗馬的五分之一糧食，透過蒸汽機可以輸出的機械功率比平均馬
隻多出四倍。