running the rafter level through a field to guide the ploughs horizontally, Thruston makes a step of the level (10 f.) every minute, which is 600. f. = 200. yds an hour.
In terrassing the new nursery in 4. f. terrasses, 2 men do 50. yds in length a day.
we find that in blowing rock it takes 2. oz. of powder to a blast, taking one depth of hole with another.*
2. bars of tin weighing 12.8 oz. or 3/4 lb each have tinned 18. stewpans being our whole number. then it takes 1. lb to tin a dozen stewpans.
3 men & 3. lads get 550. bolts of stave timber for flour barrels in a day. each bolt makes 4. staves or heading pieces, & 25 staves & heading pieces make a barrel.
in blowing on the river road at the foot of Monticello, I found pretty accurately that each borer used 1/4 lb powder a day, & bored 3 holes of 12 I. each a day. this gives 1 1/3 oz. to the blast
Colclaser says that a man saws & rives the timber & dresses compleatly for setting up staves for 250. barrels a day, 17. staves to a barrel.