Resistance To Lateral Pressure Or Transverse Actio 46Resistance To Lateral Pressure Or Transverse Actio 47

And these applications of principle not only tend to diminish deflection, but the required purpose is also more effectively attained, and that by lighter pieces of timber.

To ascertain the absolute strength of a cast iron beam of the preceding form, or that of strongest section, amounts to one-fifth of the cylinder's external diameter; the relative stregth a to that of a hollow cylinder being as the diameters of their section Talks.)

RULE.-Multiply the sectional area of the bottom flange in inches by the depth of the beam in inches, and divide the product by the distance between the tupports, also in inches; and 514 times the quotient equal the absolute strength of the beam in ewis.

The strongest form in which any given quantity of matter can be disposed that of a hollow cylinder; and it has been demonstrated that the maximum of strength is obtained in cast iron, when the thickness of the annulus, or ring.

A Table showing the Weight or Pressure a beam of Cast Iron, 1 inch in breadth. wul sustain, without destroying its elastic force when it is supported at each end, and loaded in the middle of its length, and also the defection in the middle which that weight will produce. By Mr. Hodgkinson, Manchester.

Length.

6 feet.

7 feet.

8 feet.

9 feet.

10 feet.

Depth in in.

Weight in lbs.

Defl. in in-

Weight in lbs.

Defl. in in.

Weight in lbs.

Defl. in in.

Weight in lbs.

Defl. in in.

Weight in lbs.

Defl. in in

3

1278

.24

1089

.33

954

.426

855

.54

765

.66

3*

1739

.205

1482

.28

1298

.365

1164

.46

1041

.57

4

2272

.18

1936

.245

1700

.32

1520

.405

1360

.5

4

2S75

.16

2450

.217

2146

.284

1924

36

1721

.443

5

3560

.144

3050

.196

2650

.256

2375

.32

2125

.4

6

5112

.12

4356

.163

3816

.213

3420

.27

3060

.33

7

6958

.103

5929

.14

5194

.183

4655

.23

4165

.29

8

9088

.09

7744

.123

6784

.16

6080

203

5440

.25

9

9801

.109

8586

.142

7695

.18

6885

.22

10

12100

.098

10600

.128

9500

.162

8500

.2

11

12826

.117

11495

.15

10285

.182

12

15264

.107

13680

.135

12240

.17

13

16100

.125

14400

.154

14

18600

.115

16700

.143

12 feet.

14 feet.

16 feet.

18 feet.

•20 feet.

6

2548

•48

2184

.65

1912

.85

1699

1.08

1530

1.34

7

3471

.41

2975

.58

2603

.73

2314

.93

2082

1.14

8

4532

.36

3884

.49

3396

.64

3020

.81

2720

1.00

9

5733

.32

4914

.44

4302

.57

3825

.72

3438

.89

10

7083

.28

6071

.39

5312

.51

4722

.64

4250

.8

11

8570

.26

7346

.36

6428

.47

5714

.59

5142

.73

12

10192

.24

8736

.33

7648

.43

6796

.54

6120

.67

13

11971

.22

10260

.31

8978

.39

7980

.49

7182

.61

14

13883

.21

11900

.28

10412

.36

9255

.46

8330

.57

15

15937

.19

13660

.26

11952

.34

10624

.43

9562

.53

16

18128

.18

15536

.24

13584

.32

12080

.40

10880

.5

17

20500

.17

17500

.23

15353

.30

13647

.38

12282

.47

18

22932

.16

19656

.21

17208

.28

15700

.36

13752

.44

Note.-This Table shows the greatest weight that ever ought to be laid upon a beam for permanent load; and, if there be any liability to jerks, etc, ample allowance must be made; also, the weight of the beam itself must be included. [See Tables of Cast Iron.)

To find the weight of a cast iron beam of given dimensions.

Rule.-Multiply the sectional area in inches by the length in feet, and by 3.2, the product equal the weight in lbs.

Ex. Required the weight of a uniform rectangular beam of cast iron, 16 feet in length, 11 inches in breadth,and 1 inch in thickness.

11 X 1.5 X 16 X 3.2 = 844.8 lbs.