Estimate of one mile of screw propeller.

s.

d.

33 tons cast iron shafting, including the bearings and fitting the coupling joints, at 10......

330

0

0

17 tons, wrought and rolled iron, in arms and spiral, the arms driven on hot and keyed, and the spiral secured to the arms with hot rivets, at 17 10s. ....................

297

10

0

10 tons of cast iron, in saddles or pedestals, by which the propeller is supported, at 7 ............................................

70

0

0

1 ton of wrought iron in screws, pins and keys .........................

20

10

0

1,760 yards of screw propeller laid down for fixing, bushings and sundries, at 1s. 6d. .........................................

0

0

850

0

0

Estimate of power for locomotion on three miles of double line of railway.

1 steam engine, 20 horse power, or two 10 horse engines, including gearing, at 30 ......................................

600

0

0

Engine house and sundries .....................................................

250

0

0

850

0

0

Interest on 850, at 5 per cent. per annum ....

42

10

0

Coals for one 20 horse engine, working 12 hours per day, 365 days at 8s. per day ..................................................

146

0

0

Attendance, wear and tear, and sundries ..................................

150

0

0

Apparatus connected with the carriages ...................................

50

0

0

388

10

0

64

15

0

Interest on 850, the first cost of propeller at 5 per cent .........................................................................

42

10

0

Total annual expense of one mile . .

107

5

0

Thus the total expense of locomotion for a single mile for one year is 107 5s. Od. not quite 6 shillings per day of 12 hours. The foregoing estimates, show the expense of the system, as applied to any part of the present railways; but in any new railway formed with reference to the application of this system, the saving on the rails alone will pay more than one half the cost of the propeller; and the saving in cuttings and embankments, bridges, etc. will render the formation of railways on this system scarcely, if at all, more expensive than a turnpike road.

The following is an estimate of the upper works of the Archimedean system complete, compared with the locomotive system, omitting those items that are common to both.

ARCHIMEDEAN SYSTEM.

s.

d.

Cost of one mile of propeller as before detailed ....................

850

0

0

26 tons of cast iron tubing in guide rails at 10 0 0

260

0

0

10 tons of cast iron in additional weight of bearing saddles, at ..................................................... 7 0 0

70

0

0

13,040 feet lineal of longitudinal and cross sleepers of Paynized wood, including laying, at . . . 0 1 6

1023

0

0

1,800 screw bolts and nuts, at ................................ 0 1 2

15

0

0

Cost of a single mile ................................

2218

0

0

LOCOMOTIVE SYSTEM.

13,640 lineal oflongitudinal and cross sleepers, including laying, at ................................................................. 0 1 4

909

6

8

Rolled iron rails, 801bs. per yard, 126 tons, including laying, the rails, at ............................................. 10 0 0

1260

0

0

8,840 screw bolts and nuts, in rails and sleepers 0 0 2

73

13

4

Cost of a single mile ......................

2243

0

0

From the foregoing it may be seen, that the expense of the Archimedean system complete, including (Paynized) wooden sleepers, will not exceed the cost of the upper works of the present locomotive system; that the expense of power for locomotion, for 12 hours continuous traffic, will be less than 65 per mile, per annum; and if it shall be found advisable to double the engine power that I allow, and thus work three miles of propeller at the same time, instead of 1 1/2 mile, by which means the traffic may also be doubled, the annual cost will not amount to 100 per mile of single line, or 200 per mile of double line; while the cost of power on the locomotive system may be taken at an average of 1000 per mile; but on short lines, and where there is large traffic, it far exceeds that sum.

I would in conclusion observe, that all that has been said in reference to the saving that may be effected in cutting embankments, bridges, etc, in the formation of railroads adapted to the atmospheric principle, applies equally to the Archimedean: that saving will be great on the most favourable lines, and in many cases it will amount to thousands of pounds per mile.