At 17 miles per hour she burns 202 tons per day.
At 18 miles per hour the consumption is 240 tons per day.
At 19 miles per hour she burns 283 tons coal per day; and
At 20 miles per hour she burns 329 tons per day. At 20 miles per hour she would run 480 miles per day, a thing as yet wholly unheard of, and would consume on the voyage of 6 days and 16 hours, say 6 days and 22 hours, 2,276 tons of coal. It would be clearly impossible for her to carry her own fuel; as the immense boiler and engine power necessary to secure this speed would of itself fill a ship of this size, to say nothing of the fuel which also would nearly fill it. Then, we may never expect any such ship to attain any such speed as seventeen, eighteen, or twenty miles per hour on so long a voyage without recoaling.
Seeing thus the enormous increase in the consumption of fuel for a moderate increase in the speed, we are enabled the better to appreciate the large expense incurred in running ocean steamers sufficiently rapidly for successful mail and passenger purposes. We will further pursue these inquiries by examining in this table the consumption for vessels of 6,000 tons, which would make the displacement of the ship nearly 5,000 tons, such as the "Adriatic," the "Vanderbilt," and the "Niagara." It appears that at 8 miles per hour they would consume 33 tons per day; at 10 miles, 65 tons; at 12 miles, 113 tons; at 13 miles, 144 tons; at 14 miles, 179 tons; at 15 miles, 221 tons; and at 16 miles, 268 tons per day. This is supposing this speed to be maintained on an average across the ocean, in all kinds of weather, which this size of steamer could not do without more engine and boiler power than any of them have. With such additional power the ships noticed would have scarcely any available room for freight or any thing else. One thing is very clear from this table, that when steamers run at very moderately slow rates of speed, their consumption of fuel is very small; and that when they leave this low freighting speed, for that of the necessarily rapid mails and passengers, the consumption increases to an extent and with a rapidity that would seem almost incredible at first view.
COAL TABLE: No. II.
The following coal table is constructed in all respects as the preceding, but for a lower type of vessels, or those whose coëfficient of Dynamic performance is inferior to that upon which the previous table is estimated. As a consequence, this style of vessel requires more fuel.
| SHIP'S DISPLACEMENT. | SPEED PER HOUR.—NAUTICAL MILES. | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | |
| TONS. | TONS | TONS | TONS | TONS | TONS | TONS | TONS | TONS | TONS | TONS | TONS | TONS | TONS | TONS | TONS |
| 500 | 3.95 | 6.28 | 9.37 | 13.4 | 18.3 | 24.3 | 31.6 | 40.1 | 50.2 | 61.7 | 75.0 | 89.9 | 106 | 125 | 147 |
| 600 | 4.46 | 7.10 | 10.6 | 15.1 | 20.6 | 27.5 | 35.7 | 45.3 | 56.6 | 69.8 | 84.6 | 101 | 120 | 141 | 165 |
| 700 | 4.95 | 7.86 | 11.7 | 16.6 | 22.8 | 30.5 | 39.5 | 50.3 | 62.9 | 77.3 | 93.8 | 112 | 134 | 157 | 183 |
| 800 | 5.41 | 8.59 | 12.8 | 18.2 | 25.1 | 33.3 | 43.3 | 55.0 | 68.7 | 84.5 | 102 | 123 | 145 | 171 | 200 |
| 900 | 5.85 | 9.29 | 13.9 | 19.7 | 27.0 | 36.0 | 46.8 | 59.5 | 74.3 | 91.5 | 111 | 132 | 158 | 186 | 217 |
| 1000 | 6.28 | 9.97 | 14.8 | 21.2 | 29.1 | 38.7 | 50.1 | 63.8 | 79.7 | 98.1 | 119 | 143 | 169 | 199 | 232 |
| 1250 | 7.28 | 11.5 | 17.3 | 24.5 | 33.8 | 44.8 | 58.2 | 74.1 | 92.5 | 114 | 137 | 165 | 196 | 231 | 270 |
| 1500 | 8.23 | 13.0 | 19.5 | 27.8 | 38.1 | 50.7 | 65.7 | 83.7 | 104 | 128 | 156 | 187 | 222 | 261 | 304 |
| 1750 | 9.11 | 14.4 | 21.5 | 30.8 | 42.2 | 56.1 | 72.9 | 92.7 | 115 | 143 | 173 | 206 | 245 | 290 | 338 |
| 2000 | 9.95 | 15.8 | 23.6 | 33.6 | 46.1 | 61.5 | 79.7 | 101 | 126 | 159 | 188 | 226 | 269 | 316 | 369 |
| 2500 | 11.5 | 18.3 | 27.4 | 39.0 | 53.5 | 71.2 | 92.5 | 117 | 147 | 180 | 219 | 262 | 312 | 368 | 427 |
| 3000 | 13.0 | 20.8 | 30.9 | 44.0 | 60.4 | 80.4 | 104 | 132 | 166 | 204 | 248 | 296 | 352 | 414 | 483 |
| 3500 | 14.4 | 23.0 | 34.3 | 48.8 | 66.9 | 89.1 | 115 | 147 | 183 | 226 | 274 | 329 | 391 | 460 | 535 |
| 4000 | 15.8 | 25.1 | 37.4 | 53.4 | 73.2 | 97.5 | 126 | 161 | 201 | 247 | 300 | 360 | 427 | 501 | 586 |
| 5000 | 18.3 | 29.1 | 43.5 | 62.0 | 85.0 | 113 | 147 | 187 | 232 | 287 | 348 | 417 | 495 | 582 | 679 |
| 6000 | 20.6 | 32.9 | 49.1 | 69.9 | 95.9 | 127 | 166 | 210 | 264 | 323 | 392 | 472 | 560 | 657 | 768 |
| 10000 | 29.1 | 46.2 | 69.0 | 98.2 | 135 | 179 | 232 | 296 | 370 | 455 | 552 | 663 | 786 | 925 | 1079 |