123. Masonry, brickwork and gauging

The lesson, step by step

1. Warm-up

   Ask: How might a builder in 1880 price a stone wall or a brick chimney?

2. Old measures

   Stone masonry was sold by the perch. Earlier in the book, a perch of stone is a mass 16½ ft. long, 1½ ft. wide and 1 ft. high, which is 24¾ cubic feet. Bricks were counted by the thousand. The book notes that brick work is generally estimated by the thousand bricks, and gives the usual size of a brick.

3. Brickwork example

   Work together:

   How many bricks of ordinary size will build a square chimney 86 ft. high, 10 ft. wide at the bottom, and 4 ft. at the top outside, and 3 ft. wide inside all the way up?

   Read the book's hint:

   Find the solidity of the whole chimney, then of the hollow part; the difference will be the solid part of the chimney.

4. Gauging

   Read:

   Gauging is finding the contents of vessels, in bushels, gallons, or barrels.

   Find the solidity of the vessel in cubic inches by the rules already given; this divided by 2150.42, will give the contents in bushels; by 231, will give it in wine gallons, which may be reduced to barrels by dividing the number by 31½.

5. Casks

   Read how to find a cask's mean diameter:

   Add to the head diameter (inside) two thirds of the difference between the head and bung diameters;

   Then square it, multiply by the length in inches and by .0034. Try:

   In a barrel of whisky, with staves slightly curved, length 2 ft. 10 in., bung diameter 1 ft. 9 in., head 1 ft. 6 in.

   (For slightly curved staves the book uses six tenths of the difference.)

6. Independent practice and wrap-up

   Your student works a few more and checks the printed answers. Ask: Why multiply by .0034 instead of by π ÷ 4 and then dividing by 231? (It is the same thing done in one step.)