(a) A very good form of lamp can be made of a 3 neck globe, to be procured at the chemical apparatus shops, in the shape of Fig. 112: a is the globe and 6 two of the necks, which should be fitted with corks, drilled to receive pieces of No. 1 brass wire, and then cemented in. Fig. 113 shows one of the brass wires drilled about 1/4 in. down to receive a length of carbon, and a hole at the other end to fasten the connecting wires to. A piece of very fine carbon is inserted between the wires (about 1 in. long by 1/16 in.) leaving 1/2 in. exposed. The globe is filled with nitrogen by burning out the oxygen in the following manner: - A stopcock is cemented into the third neck and then screwed into a capped gas,jar, which is placed in a pneumatic trough with a

The Telescope.

The Telescope.

T, paper tube; P, draw tube; L, lens; W, wire.

Lighting

The following tables are very useful:

Table I. - Cost Of Laying 100 Yd. Of Double Conductor Underneath The Footway of A London Street

Single No. 16.

7/16

19/15

19/12

19/10

37/10

2 Sets. 37/10

4 Sets

37/10

6 Sets. 37/10

Area sq.in...

•0032

•0225

•0773

•1613

0.25

0.5

1.0

2.0

3.0

Area, sq. mm. .

2.08

14.6

50

104

161.25

322

645

1290

1935

Weight per 100 yd. run, lb...

7 1/2

53 1/2

183 1/4

392

576

1153

2306

4612

6918

s.

d.

8.

d.

8,

d.

8.

d.

s.

d.

s.

d.

s.

d.

s.

d.

s.

d.

Cost of copper at 7 3/4d. ..

0

4

10

1

14

6

5

18

0

12

13

0

18

15

0

37

5

0

74

10

0

149

0

0

224

0

0

Cost of insulation ...

1

3

2

4

8

6

11

2

0

24

17

0

35

17

0

70

15

0

141

10

0

283

0

0

424

0

0

Total cost of cables..

1

8

0

6

3

0

17

0

0

37

10

o

54

12

0

108

0

0

216

0

0

432

0

0

648

0

0

Casing, bitumen, & cement..

5

3

0

5

5

0

8

0

012

10

o

12

10

0

16

0

0

22

0

0

40

0

0

55

0

0

Labour, laying.

3

0

0

4

0

0

5

0

0

5

0

o

6

0

0

10

0

0

.18

o

0

35

0

0

50

0

0

Trenching and repairing...

25

0

0

25

0

0

25

0

0

25

0

o

25

0

0

25

0

0

25

0

0

30

0

0

35

0

0

Surface .boxes & connection..

5

0

0

7

0

0

10

0

0

10

0

0

10

0

0

10

0

0

10

o

0

10

0

0

10

0

0

Engineer & superintendent.

3

0

0

4

0

0

5

0

0

5

0

0

6

0

0

10

0

0

10

o

0

20

0

0

25

0

0

Total...

42

11

0

51

8

0

70

0

0

95

0

0114

2

0

179

0

0

301

0

0

567

0

0

23

0

0

Add extra, if copper at 9 1/2d..

0

1

1

0

8

0

1

7

0

2

17

0

3

5

0

8

10

0

17

0

0

'34

0

0

51

0

0

42

12

1

51

16

0

71

7

0

97

17

0

117

7

0

187

10

0

318

0

0

601

0

0

874

0

0

Cost of copper per lb. laid complete..

5

13

6

0

19

4

0

7

9

0

5

0

0

4

1

0

3

3 1/2

0

2

8 3/4

0

2

7 1/4

0

2

6 1/4

Current in amperes ,..

1.2

8.1

28

58

90

180

360

720

1

080

Cost per ampere.

35

10

0

6

8

0

2

10

6

1

13

9

1

6

0

1

1

0

0

17

6

0

16

8

0

16

1

Table II. - Cost Of Laying 100 Yd. Of Double Conductor of Babe Copper Carried On Insulators In A Culvert

Area in sq.in..

0.25

0.5

1.0

2.0

2.55

3.00

Area in sq.mm..

161-25

322.5

645

1290

1645

1935

Weight of copper in lb .per 100yd..

576

1153

2306

4612

6125

6918

s.

d.

s.

d.

s.

d.

s.

d.

s.

d.

s.

d.

Cost of copper at 7 3/4d .per lb..

18

15

0

37

5

0

74

10

0

149

0

0

190

0

0

224

0

0

Laying..

9

0

0

9

12

0

9

12

0

9

15

0

9

15

0

10

0

0

Insulator..

0

4

6

0

4

6

0

4

6

0

4

6

0

4

6

0

4

6

6 surface boxes and connections..

10

0

0

10

0

0

10

0

0

10

0

0

10

0

0

10

0

0.

Culvert, 18 in. x 12 in., for two lines conductor, in brickwork and cement, replacing payement. .

53

8

0

53

8

0

53

8

0

53

8

0

53

8

0

53

8

0

Engineers for copper at 9 1/2d.per yd..

6

0

0

10

0

0

10

0

0

10

0

0

10

0

0

15

0

0

Total..

97

7

6

120

9

6

157

14

0

232

7

6

263

7

6

312

12

6

Extra for copper at 9 1/2d per lb..

3

5

0

8

10

0

17

0

0

34

0

0

43

10

0

51

0

0

Total..

100

12

6

128

19

6

174

14

6

266

7

6

306

7

6

363

12

6

Cost of copper per lb. laid complete..

42d.

27d.

18.2d

13.8d.

12d.

12.8d.

Current in amperes..

90

180

360

720

910

1080

Cost per ampere...

1

2

3

0

14

5

0

9

8

0

7

5

0

6

9

0

6

8 1/2

Table III. - Cost Of 10,000-Light Or 600-Kilowatt Plant

A.T. - Alternating Transformer

- Distribution.

Generating station, buildings, chimney shaft, water tanks, and general fittings ....

11,000

Dynamos and exciters - 865 kilowatts, including spare sets, divided as convenient.

5,540

Motive power, i.e. engines, boilers, steam and feed connections, belts, etc, at 8/. 12s.

per I.H.P. ........

12,470

500 transformers, i.e. one to every pair of houses, at 15/.

each ...........

7,500

2000 yd. primary or charging main, exterior to area of supply, at 308/. per 100 yd.

6,160

20,000 yd. distributing main, 50 mm. sectional area, at 91l. 7s. (see Table I.) . .

14,270

Regulating gear ...........

500

57,440

B.T. - Accumulator Transformer

Distribution.

Generating station, buildings, chimney stack, water tanks, and general fittings .

8,000

Dynamos - 600 kilowatts, in 6 sets of 100 kilowatts each .

4,800

Motive power, i. e. engines, boilers, steam and feed connections, etc, at 8/. 12s, per

I.H.P. .........

8,600

4 groups of accumulators, in all 240 cells, in series, at 40/. per cell, including stands .

9,600

2000 yd. charging main, at 306l. 17s. 6d. per 100 yd.

(see Table II) .......

6,137

20,000 yd. distributing main, 161.25 mm. sectional area, at 100l. 12s. 6d (see Table

II.)......

20,125

Regulating gear ...........

2,500

59,762

Table IV. - Working Expenses And Maintenance Of 10,000-Light, Or 600-Kilowatt Plant

A.T.

B.T.

Materials-

s.

d.

s.

d.

s.

d.

s.

d.

Coal: 4380 tons at 17s.

3,723

0

0

.

> ■

„ 2550 „ 17s.

2,167

0

0

Oil, water, and petty stores: 1500 hours' at 7s. 6d. + 7520 hours at 1s.....

925

0

0

> •

Oil, water, and petty stores: 1400 hours at 5s.

350

0

0

• •

Total cost of material.

4,648

0

0

2,517

0

0

Labour-

2 foremen drivers at 45s., 6 drivers at 30s., 9 fire-men at 24s.; sundry labour..

1,388

8

0

1 foreman driver at 45s. 2 drivers at 30s., 3 fire men at 24s.; sundry labour...

.

975

0

0

• •

AT.

B.T.

Brought forward . .

s.

d.

s.

d.

s.

d.

s.

d.

1,388

8

0

4,648

0

0

975

0

0

2,517

0

0

Salaries-

1 chief at 500l., 2 assist ants at 200l. each, 4 clerks at 80l. each .

1,220

0

0

1 chief at 500/., 1 assist-ant at 200/., 4 clerks at

80l.each..

.

1,020

0

0

2,608

8

0

---------------

1,995

0

0

Maintenance of Plant -

Motive power and dyna-mos: 10 per cent, on 18,010/....

1,801

0

0

Motive power and dynamos: 10 per cent, on

13,400l..

..

.

1,340

0

0

Buildings and fittings: 5 per cent, on 11,000l.

550

0

0

Buildings and fittings 5 per cent, on 8000l..

400

0

0

Transformers: 10 per cent, on 7500l. .

750

0

0

Accumulators: 15 per' cent, on 9600l...

1,440

0

0

Mains: 7 1/2 per cent, on 20,430l. ...

1,532

5

0

Mains: 2 1/2 per cent. on 26,262l. ...

■ •

656

10

0

- ,

Regulating gear: 10 per cent, on 500l. .

50

0

0

Regulating gear: 10 per cent, on 2500l. .

250

0

0

4,683

5

0

4,086

10

0

11,939

13

0

8,598

10

0

2100 units X 365 days =) 766,500 units. Cost per unit..

• •

3.75d.

• •

2.7d.

piece of phosphorus on a little stand (Fig. 114). When all is ready, the P is lighted by a hot wire, the jar placed over it, and the stopcock opened. Phosphoric acid is formed, which eventually dissolves in the water. When the globe (R. E. B. Crompton.) is quite clear again, shut the stopcock, and unscrew the globe from the jar. It can then be screwed to any of the gas brackets, and insulated wires running inside or outside the gaspipe from a battery of at least 6 large Bunsens. A very fair light is the result, increased of course by the number of cells employed (Fig. 115). The globe can be bought at Jackson's, 65, Barbican, for about 1s.

(6) Fig. 116 is a regulator lamp of my own design, and which works very well indeed (the box is removed for clearness); A is the positive carbon-holder, which takes 8 in. of carbon, and B, the negative, which tabes 4 in. These slide in tubes. A being the heavier; F C E is a lever with its fulcrum at C, the end E being half as long as F. The E end is connected by an ivory or bone connecting-rod to B, as shown, and the end of F by similar means to F from E. On the negative carbon-holder hangs an iron cylindrical weight, which slides easily in the coil G. When no current ia passing, the carbons touch; but when the current is switched on, the iron weight is drawn down the coil,and the electric arc is formed. On the current becoming weaker, the positive carbon falls, forcing up the negative half the distance by means of tbe lever PCE. This restores the arr, and the carbons are locked by the coil. Any other arrangement may be employed to lock the carbon, the chief point claimed for this lamp being its simplicity. (C. Crawford Cory.)

Home made lamp.

Home-made lamp.