8
ON PADDLE-WHEELS.
TABLE I.
Name ofthe vessel.
Tonnage.
Horse
power.
Effectivepressureexertedby theengine.
Velocity ofthe vessel,that of thewheelbeing 1.
Velocity ofthe verticalpaddlesthrough thewater, that ofthe wheelbeing 1.
Area ofthe paddleboard.
Area ofa verticalpaddleequal ineffect to allthe paddles.
Immersedsectionalarea ofthe vessel.
Ratio of theresistance ofthe vesselto that of aplane surfaceof the samesection.
lbs.
feet.
in.
Medea
835
220
4536
•627
•373
19
0
54-00
263
TnP
Flamer
494
120
2814
•683
•317
16
0
52-44
174
1
Flamer
494
120
2593
•674
•326
16
0
57-60
218
tV
Firebrand
494
120
2472
•667
•333
12
9
38-56
200
tV
Firebrand
494
120
2527
•666
•334
12
9
42-00
214
i
Ta
Columbia
300
100
1807
•654
•346
12
0
43-10
202
i
i-A
Salamander
820
220
2150
•833
•167
22
6
398-70
359
i
ITT
Dee
710
200
2531
•732
•268
20
0
69-00
209
i
TIT
Firefly
550
140
3808
•733
•267
18
0
201-00
275
i '
Firebrand
494
140
2474
•772
•228
18
0
128-61
200
i
TT
Pluto
365
100
985
•823
•117
16
6
105-23
116
i
Monarch
872
200
7167
•748
•252
20
0
Monarch
872
200
6976
•746
•254
20
0
Monarch
872
200
7002
•756
•244
20
0
Magnet
360
140
3672
•763
•237
15
0
Meteor
296
100
4320
•671
•229
13
6
Carron
294
100
1731
•777
•323
13
6
i.
2.
3.
4.
5.
6.
7.
8.
9.
10.
“ It thus appears, contrary to the results of all experiments hitherto made on the small scale,that the resistance of a well-shaped vessel does not exceed -j^th part that of a plane of the samesectional area.
“ The above mean, being founded on several experiments, must be very near the truth; althoughin each so much error may exist, from the want of minute attention to the number of strokes ofthe engine, as to afford no test of the best shaped vessel.
“ As, however, the results are very extraordinary, it may be well to submit them to a totallyindependent mode of estimation. In the above investigation, the mean number of acting paddles,with their corresponding velocities and areas, are compared with the sectional area of the vessel andits velocity; but we might have made the calculation in another way,—that is, by comparing theforce necessary to urge a plane section equal to that of the vessel with the velocity at which it passesthrough the water, with the actual power of the engine employed to propel the vessel,—which oughtto give nearly the same fraction as the other method.
“ Of the whole power of the engine, we have seen that with the vertically-acting paddle one-thirdis lost by the retrograding of the wheel: in the ‘ Medea,’ therefore, the power employed in propellingthe vessel is two-thirds of 220 = 146 horse-power: now the velocity of the vessel having been
11-33 English miles per hour, or 16 - 62 feet per second, the resistance in feet of water is ^ and
64-g-
(16 62) x 621 -, on each square foot. The number of feet in the section is 263, and the velocity
in fts.
641
in feet per minute is 997; the whole force, therefore, expended in a minute, is 70,796,970, which,divided by 33,000, gives 2150 horse-power for the force necessary to urge a plane section of 263 feetthrough the water at the rate of 11*33 miles per hour: but the vessel itself is urged with that velocityby the power of 146 horses ; the resistance to a vessel is therefore to that of a plane section of thesame area as 146 to 2150, or as 1 to 15 very nearly, which exactly agrees with the number givenin the Table. The agreement is equally close in the ‘ Flamer; ’ and the mean obtained this wayfrom the whole set of experiments is very nearly the same as that given in the above Table.