These levers turn upon the pin of the propelling cranks dand e, and are guided in their motions by the radius rods h and i, connected to their upper ends. The radius rods are connected to a cast iron frame, k, which is supported on two brackets, ll, attached to the side of the vessel. The principal dimensions of the apparatus are as follows:-

Section I Historical Outline Of The Rise And Progr 531

Feet

In.

Diameter of cylinder .....................................................

0

10 3/4

Length of stroke ............................................................

2

0

Diameter of the spur wheels at the pitch lines ................

4

10

Feet

In.

Diameter of the paddle cranks............................

3

0

Breadth of paddles.......................

2

0

Depth of ditto...............................

2

0

Subsequently to the instance of the Maria, numerous vessels have been fitted with auxiliary steam power; and "auxiliary steamers " are now employed on several trading lines. These being built expressly for the purpose, have, in most cases, screw propellers. Amongst the largest of these vessels is the Antelope, of 600 tons, and the Emerald, of 700 tons, and 50 horse power, trading between London and Belfast; and the Sarah Sands, of 1000 tons, trading between Liverpool and Rio Janeiro.

The government likewise appear to appreciate the advantages which may accrue to the navy from the application of steam as an auxiliary. In addition to several guardships at the different ports so equipped, the Amphion, 36 gun frigate, of about 1500 tons burthen, has been fitted with a screw propeller, driven by engines of 300 horse power. By means of this steam power, she can, it is stated, command a speed, under ordinary circumstances, of nearly 7 knots per hour under steam alone; and with steam and sail combined, a speed which in all cases shall render her superior to every other mere sailing ship she may meet with. Another "auxiliary" frigate, the Arrogant, of 1850 tons and 360 horse power, with a screw propeller, is building.

The following Table contains some of the dimensions of the hull and machinery of some of the largest steam vessels yet built.

DIMENSIONS.

Great Western.

Terrible, Steam Frigate.

British Queen.

President.

Great Britain.

Extreme length . . . . .. . . .

236

-

275

265

322

feet.

Ditto, under Deck . . . . .. . . .

212

-

245

238

-

"

Ditto, Keel . . . . .. . . . . . . . ..

205

226.2

225

220

289

"

Breadth within the Paddle Boxes

35.4

42.6

40

41

51

"

Ditto, including ditto . . . . .. . . . .

59.8

-

64

64

-

"

Depth of Hold at Midships ... .

232

27.4

27.6

23.6

36

"

Tons of Space . . . . .. . . . .

679 1/2

-

1053

-

1000

tons.

Tonnage of Engine Room . .. .

64l 1/2

-

963

-

-

"

Total Tonnage . . . .. . . . .

1821

1850

2016

1840

3443

"

Power of Engines . . . .. . . . .

450

-

500

540

-

horses.

Diameter of Cylinders. . . . .. . . .

73

-

77 1/2

80

4 of 88

inches.

Length of Stroke . . . . .. . . .

7

-

7

7 1/2

6

feet.

Diameter of Paddle Wheels . ..

28.9

-

30.6

31

-

"

Total weight of Engines, Boiters and Water . . . . .. . . . . . .

480

-

500

500

740

tons.

Total weight of Coals, 20 days consumption . . .. . . . . . .

600

-

750

750

1000

"

Total weight of Cargo . . . . .. . . .

250

-

750

750

-

"

Draught of water with the above weight of Stores . . . . . . . .. .

16.8

18.9

16.7

17

16

feet