6. Explain why a troy ounce is heavier than an avoirdupois ounce?

7. How much heavier is an avoirdupois pound than a

troy pound?

APOTHECARIES' WEIGHT.

Apothecaries' Weight is used in weighing medicines required for prescriptions.

1. How many grains in 69? 90? 120? 70?
2. How many scruples in 73?
3. How many drams in 129?
4. How many drams in 63?

5. How many ounces in 963?

83? 613? 933? 510? 279? 420? 713? 823? 113? 1443? 17283? 17283?

6. How many. pounds in 843? 1443?

Problems.

1. How many 2-grain pills can be made from a dram of quinine?

2. How many 4-grain pills can be made from 63 29 of quinine?

3. Find the cost of 8b 63 of a medicinal substance at 25 cts. an ounce.

4. What is the cost of 63 of a drug sold at 2 cts. per

scruple?

5. What is the value of 5043 of chloride of sodium, sold at 1 cts. per pound?

6. How many 5-grain pills can be made from 73 29 of calomel?

1. How many inches are there in 1 ft.? 3 ft.? 7 ft.? 12 ft.?

2. How many inches are there in 2 ft. 9 in.? 3 yd.? 1 yd.?

3. How many feet are there in 36 in.? 84 in.? 132 in.?

4. How many yards are there in 10 ft.? 18 ft.? 51 ft.? 1728 in.?

5. How many yards are there in 2 rods? How many feet in 2 rods?

Problems.

1. On my bicycle yesterday I rode 5 miles. How many rods did I ride?

2. My horse is 84 in. high. How many hands high is he?

3. Compute the number of yards in a mile. The number of feet.

4. A sounding gives 40 fathoms of sea-depth. What is the depth in feet? In yards?

5. How much will 25 yd. of garden hose cost at 9 cts. a foot?

6. How many rails, 10 yd. long, will be required to build a railroad 5 miles long?

7. Find the cost of 1100 yd. of fence, at $5 a rod.

SURFACE MEASURE.

1. Surface or Square Measure is used in measuring A surface has only length and

surface.

breadth.

This page at which you are looking is a surface. 2. An Angle is the difference in direction of two lines drawn from the same point.

3. A Square has four equal sides and four equal angles. The equal angles are called right angles.

Angle.

Square.

Table.

144 Square Inches (sq. in.) = 1 Square Foot (sq. ft.).

Rectangle.

The name Rectangle applies to the square and to all other figures with four sides and four right angles.

Exercises.

1. How many square inches are there in 3 sq. ft.? 5 sq. ft.? 10 sq. ft.?

2. In 10 sq. yd., how many square feet? 12 sq. yd.? 15 sq. yd.? 20 sq. yd.?

3. In 3 sq. rd., how many square yards? 4 sq. rd.? 8 sq. rd.? 10 sq. rd.?

4. 320 acres is what part of a square mile?

5. Compute the number of square yards in an acre.

Problems.

1. If you divide a 10-acre field into lots, each of which contains 100 sq. rds., how many lots will there be?

2. How many acres in a field 60 rods long and 20 rods. wide?

3. A lot 16 rods long contains an acre. How wide is it?

4. 5 boards are each 16 ft. long and 15 in. wide. How many square feet in them?

5. Draw a figure to show the difference between a surface of 4 sq. ft. and one 4 ft. square.

LESSON IV.

VOLUME MEASURE.

1. Volume or Cubic Measure is used in measuring that which has length, breadth, and thickness.

2. The volume of a body is called its Solid Contents, and the body is called a Solid.

3. A solid with six equal square faces is called a Cube.

When each face is an inch square, the solid is a cubic inch.

When each face is a foot square, the solid is a cubic foot.

4. The name Rectangular Prism applies to cubes and other solids whose faces are rectangles.

Cube.

Prism.

Table.

1728 Cubic Inches (cu. in.) = 1 Cubic Foot (cu. ft.).