by Thomas Jefferson
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The two-wheeled barrow carries 4. loads of the single one, at once.
it is loaded, & carried 30. yards in 3' + 1 1/2 4' 1/2 [minutes]
it will do then exactly double the work in the same time. loading being equal.
a man digs & carries 50. yds. 5. cubical yards of earth in a day of 12. hours.
a man carries 75. bricks with old lime sticking to them, say 500 lb. in the two wheeled barrow on level ground.
24. cubic yards of very solid earth made 122. loads, which is 3 1/2 cub. feet to a load.