24 grains (gr.) are 1 pennyweight....pwt. 20 pennyweights 12 ounces 1lb. 12 oz. 240 pwt.=5760 gr. A Pound Avoirdupois is equal to 7000 Troy grains. 310. Apothecaries, in compounding medicines and in putting up prescriptions, either use only the denominations of grains, ounces and pounds, or subdivide the Troy pound into grains, scruples, drams and ounces. Thus, 311.-1. How many grains in 1 pennyweight? In 2 pennyweights? 2. How many pennyweights in 48 grains? 3. How many pennyweights in 2 ounces? In 5 ounces? 4. How many ounces in 40 pennyweights? In 100 pennyweights? 5. How many ounces in 3 pounds? In 10 pounds? 6. How many pounds in 48 ounces? In 144 ounces? 7. At $3.25 a pennyweight, what is the value of a jewel weighing 12 pennyweights? 8. At 3 cents a scruple, what is the value of a drug weighing 1 ounce? 9. How many doses, of 5 grains each, are there in 1 dram of medicine? WRI TEN EXERCISES. 312.-1. How many grains in 65 ounces? 2. How many ounces in 31200 grains? 3. How many pennyweights in 511⁄2 pounds? 4. How many pounds in 12360 pennyweights? 5. At 25 cents a dram, what will 80 pounds of drugs cost? 6. At 25 cents a dram, how many pounds of drugs may be bought for $1920 ? 7. If the gold coin of the United States is composed of 9 parts of pure gold and 1 part of alloy, how many pennyweights of alloy are there in 20 pounds of coin? 313. TEST QUESTIONS.-1. What are avoirdupois weights? Name the units of avoirdupois weights. Recite the table. 2. How many pounds of corn or rye are 1 bushel? How many pounds of wheat or potatoes? How many of oats? 3. How many pounds of fish are 1 quintal? How many pounds of grain are 1 cental? How many pounds of flour are 1 barrel? How many pounds of beef or pork are 1 barrel? 4. How many pounds are a quarter in the wholesale and freighting of coal? How many pounds are a hundred-weight? How many pounds in a ton? 5. What is Troy weight? What are the units of Troy weight? Recite the table. Recite the table of apothecaries' weights. 6. How many Troy grains are 1 pound Troy? How many Troy grains are equal to 1 pound avoirdupois? Which is the heavier, a pound Troy or a pound avoirdupois? SECTION XXVI. CIRCULAR MEASURES. 314. A Circle is a plane surface bounded by a line, all parts of which are equally distant from a point within called the center. 315. A Circumference is the line that bounds a circle. 316. An Arc is any part of the circumference; as AD, or DB. D 317. A Degree is one of the 360 equal parts of a circumference. 318. An Angle is the differ ence of direction of two lines which meet at a point. Thus, the lines AB and AC, which meet at A, form the angle BAC. B 319. The Measure of an angle whose sides meet at the center of a circle is that part of the circumference between the sides. Thus, the arc AD is the measure of the angle ACD which is formed in the circle, (page 146). 320. Circular Measures are those used in measuring the arcs of circles, angles and the difference of directions. The units are a second, a minute, a degree and a circumference. 1 C. 360° 21600' = 1296000". = 321. A Minute of the circumference of the earth, or a geographic mile, is about 14 common miles. 322.-1. How many seconds in 2 minutes? In 3 minutes? In 5 minutes? 2. How many minutes in 120 seconds? In 180 seconds? In 300 seconds? 3. How many minutes in 3 degrees? In 4 degrees? 4. How many degrees in 120 minutes? In 240 minutes? In 360 minutes? 5. What part of a circumference is 30 degrees? 6. How many degrees in of a circumference? WRITTEN EXERCISES. 323.-1. How many seconds in 240 degrees? 5. How many seconds in of an hour? 6. If a vessel sail 24 degrees of the circumference of the earth in one day, in how many days will it sail 180 degrees? 7. In sailing 180 degrees of the circumference of the earth, how many common miles does a vessel pass over? SECTION XXVII. MEASURES OF TIME. 324. Measures of Time are those used in measuring time or duration. The units are a second, a minute, an hour, a day and a year. 1c.y. 365 d. 8760 h. 525600 m. 31536000 s. Also, 7 days are 1 week, 12 months are 100 years are 1 century. |