TABLE OF GAUGE-POINTS FOR THE ENGINEER'S RULE.

MENSURATION OF SOLIDITY AND CAFACITY.

General rule.-Set the length upon в to the gaugepoint upon a; and against the side of the square, or diameter on D, are the cubic contents, or weight in Ibs. on c.

1. Required the cubic contents of a tree 30 feet in length, and 10 inches quarter girt.

Set 30 upon в to 144 (the gauge-point) upon a ; and against 10 upon D is 20.75 feet upon c.

2. In a cylinder 9 inches in length, and 7 inches diameter, how many cubic inches?

Set 9 upon в to 1273 (the gauge-point) upon a ; and against 7 on D is 346 inches on c.

3. What is the weight of a bar of cast iron 3 inches square, and 6 feet long?

Set 6 upon в to 32 (the gauge-point) upon a ; and against 3 upon D is 168 lbs. upon c.

By the common rule.

4. Required the weight of a cylinder of wrought iron 10 inches long, and 5 diameter.

Set 10 upon B to 283 (G. Pt.) upon a; and against 5 upon D is 66.65 lbs. on c.

5. What is the weight of a dry rope 25 yards long, and 4 inches circumference?

Set 25 upon в to 47 (G. Pt.) upon a; and against 4 on D is 53.16 lbs. on c.

6. What is the weight of a short-linked chain 30 yards in length, andths of an inch in diameter?

Set 30 upon в to 52 (G. P.) upon A ; and against 6 on D is 129.5 lbs. on c.

LAND SURVEYING,

If the dimensions taken are in chains, the gaugepoint is 1 or 10; if in perches, 160; and if in yards, 4840.-Rule. Set the length upon в to the gaugepoint on A; and against the breadth upon a is the content in acres upon B.

1. Required the number of acres or contents of a field 20 chains 50 links in length, and 4 chains 40 links in breadth.

Set 20.5 on B to 1 on a ; and against 4.4 on a is 9 acres on B.

2. In a piece of ground 440 yards long, and 44 broad, how many acres ?

Set 440 upon в to 4840 on A; and against 44 on A is 4 acres on B.

POWER OF STEAM ENGINES.

Condensing Engines.-Rule. Set 3.5 on c to 10 on D; then D is a line of diameters for cylinders, and c the corresponding number of horses' power; thus, H.Pt. 3 4 5 6 8 10 12 16 C.D. 10 in. 10 12 13 15 17 18

21

20 25 30 40

24 26 29 33

50 on c. 372 on D.

The same is effected on the common rule by setting 5 on c to 12 on D.

Non-condensing Engines.-Rule. Set the pressure of steam in lbs. per square inch on в to 4 upon a; and against the cylinder's diameter on D is the number of horses' power upon c.

Required the power of an engine, when the cylinder is 20 inches diameter and steam 30 lbs. per square inch.

Set 30 on B to 4 on A; and against 20 on D is 30 horses' power on c.

The same is effected on the common rule by setting the force of the steam on в to 250 on A.

OF ENGINE BOILERS.

How many superficial feet are contained in a boiler 23 feet in length and 5 in width?

Set 1 upon в to 23 upon a; and against 5·5 upon в is 126.5 square feet upon a.

If 5 square feet of boiler surface be sufficient for each horse-power, how many horses' power of engine is the boiler equal to ?

Set 5 upon в to 126.5 upon a; and against 1 upon в is 25.5 upon A.

TABLE BY WHICH TO FACILITATE THE CALCULATION OF BRITISH MONEY.