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Astronomy explained upon Sir Isaac Newton's principles, and made easy to those who have not studied mathematics. To which are added, a plain method of finding the distances of all the planets from the sun, by the transit of venus over the sun's disc, in the year 1761 ... / by James Ferguson
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Avoirdupoise Weight reduced into 7 roy. 103

Ex. I. In 6835 pounds 6 ounces 9 pennyweights 6 graitts 7 roy t $u.

How much Avoirdupoise weight f (See page 101.)

Avoirdupoise.

lb.

oz.

drams.

s4ooo

3291

6

13.68

j 2000

1645

11

6.84

Poundsj 800

658

4

9.14

***

..L

0

16

7

5.02

1 10

8

3

10.51

i 5

4

i

13-25

oz. 6

6

9.32

pw. 9

7.90

gr. 6

.22

Answer.

5624

10

11.88

Ex. II. In 5624 pounds 10 ounces 12 drams Avoirdupoise , Qu. Howmuch Troy weight ? (See page 102.)

Troy.

lb.

oz.

pw.

g r -

Pounds

s 5 00 °

6076

4

13

8

avoird.

\ 600) 20

729

24

2

3

0

13

0

8

4

>. 4

IO

6

16

oz. 10

9

2

7

dr. 12

13

15-08

Answer. j 6835 6 9 6.08

LEGT. VI.

Of pneumatics.

T HIS science treats of the nature, weight, and preflure of theair, and the effects arising from it.

The air is that (hin transparent fluid.body in which we live and The proper-breathe. It encompaflses the whole earth to a confiderable height; and, ties of airtogether with the clöuds and vapours that-float in it, is called the atmo-fphere. The air is justly reckoned among the number of fluids, beeaufeit has all the properstes by which a fluid is distinguiihed. For, it yields