Mr. Kirkaldy found the strength of lead pipes and of lead-encased pipes to be respectively as follows : - 1

Lead Pipe.

Lead-encased Pipe.

Internal Diamr.

Thickness.

Weight per foot.

Bursting pressure per sq. in. in lbs.

Thickness.

Weight per foot.

Bursting pressure per sq. in. in lbs.

1/2

•2

2.3

1579

•14

1.3

1859

5/8

•2

2.6

1349

•13

1.4

1454

3/4

•22

3.8

1191

•15

1.9

1416

1

•2

4.1

911

•14

2.4

1265

1 1/4

•21

5.3

683

•13

2 7

835

1 1/2

•24

7.1

734

•15

3.8

849

2

•21

9.2

498

•17

5.4

642

The tearing strength of lead pipe was 2159 lbs. per square inch, of lead-encased pipe 3759 lbs. per square inch.

Glass lined pipes may be mentioned here, though they are iron pipes lined with glass tubes. They are stated to be safe against lead poisoning, to require no soldering, to be rat proof, to have but little internal friction, and to be not liable to choke from corrosion like iron pipes. They are made from 1/2 to 21/2 inches in diameter, in various lengths up to 6 feet, with ends screwed into sockets, and with asbestos washers.

Fret Lead, for glazing, is made (as described at p. 421, Part II.) in carries, i.e. long strips, of H section, the width of the groove (i.e. the length of the cross bar of the H); the width of the face (i.e. the side of the H), and the shape of the face differ, the latter is made flat or round. There are three classes of fret lead, known as ordinary, narrow, and broad.

1 Lead Poisoning of Water and its Prevention, by A. M'Callum Gordon.

The following Table, from Seddon's Builder's Work, gives a general idea of the sizes as obtained in the market: -

Width of Grooves in inches.

Shape of Face.

Width of Face in inches.

Remarks.

Ordinary .

3/32

Flat.

7/16

Used for ordinary lead lights up to 21 oz. sheet glass.

Narrow

1/8

Flat.

5 widths from 3/16 to 1/2

Used for cathedral and thick antique glass, according to its thickness.

Narrow

3/16

Round.

2 „ 3/16 to 1/4

Broad

1/4

Flat.

5 „ 3/16 to 1/2

Broad

1/4

Round.

2 „ 3/16 to 1/4