Ray's New Higher Arithmetic · Arts. 416–419 · Unit 28: Mensuration
124. Lumber, grain and hay
Goal: Your student estimates the board feet in a log and the grain in a bin or hay in a mow, the way farmers and lumbermen did.
You'll need
- The book
- A slate, small whiteboard or scrap paper
- A notebook and pencil
What's in the book
Lumber measure by Doyle's rule, measuring grain and hay, rules and examples (answers printed), and the topical outline of Mensuration.
The lesson, step by step
Warm-up
Ask: A log is round, but boards are flat and square-edged. Why can't all of a log become boards?
Logs
Read:
To find the amount of square-edged inch boards that can be sawed from a round log.
From the diameter in inches subtract 4; the square of the remainder will be the number of square feet of inch boards yielded by a log 16 feet in length.
The book's example: a log 32 in. across and 20 ft. long. 32 − 4 = 28; 28² = 784 for 16 feet; for 20 feet, 784 × 20/16 = 980 feet.
Grain
Read:
Multiply the contents in cubic feet by .8
If it be corn on the cob, deduct one half.
For corn not shucked, deduct two thirds for cob and shuck.
Hay
Read:
Divide the cubical contents in feet by 550 for clover, or by 450 for timothy; the quotient will be the number of tons.
Guided practice
How many bushels of shelled corn, or corn on the cob, or corn not shucked, will a wagon-bed hold that is 10½ feet long, 3½ feet wide, and 2 feet deep?
A hay-mow contains 48000 cubic feet: how many tons of well settled clover or timothy will it hold?
Review
Your student does the other examples and checks the printed answers. Then read the topical outline of Mensuration and have them give a rule for each kind of figure.