The author said that he hoped to bring before the meeting im_Scientific American Supplement, No. 561, October 2, 1886

certain facts which might be of interest, and which, when recorded in

the pages of the "Transactions," might be found of some use as data

for future reference. In dealing with passenger steamers, he would do

so principally from a shipbuilder's point of view; but the moment he

commenced to think over Atlantic passenger ships as a shipbuilder, he

was met by the question whether the present tendency toward divorcing

the passenger and cargo trade from each other is likely to continue or

not. If the answer is yes, then it seems to become an important

question, for the present at least, how to build, on moderately small

dimensions, the fastest, safest, and most economical passenger

steamer, using all the most modern improvements to make her commodious

and luxurious, and an easy sea boat into the bargain. If cargo is

still to be carried in the passenger ships of the future, a moderate

speed only will be aimed at in the immediate future, and every effort

will be devoted to economy of fuel, comfort, and safety, with a fair

carrying capacity. This latter policy is one which may possibly

prevail at least for a time, as it has powerful supporters in

Liverpool; but he could not help thinking that very high

speeds--higher than we have yet attained--must eventually gain the

day. He also thought that they were on the eve of important movements,

which will indicate what the next step in the passenger trade is to

be; for it must be remembered, among other things, that none of our

present English transatlantic liners, even the latest, have yet been

fitted with the latest modern improvements for economy of fuel or

quick combustion, such as triple expansion engines or forced draught.

They must, therefore, be at some disadvantage, other things being

equal, compared with the ships of the future possessing them. The

Great Eastern steaming up Milford Haven about twenty-five years ago

between two lines of the channel fleet of old--two and three decked

wooden line-of-battle ships--the whole fleet saluting with yards

manned, was a sight to be remembered. More than this, that ship, with

all her mournful career, has been a useful lesson and a useful warning

to all naval architects who seriously study their profession--a lesson

of what can be done in the safe construction of huge floating

structures, and a warning that the highest flights of constructive

genius may prove abortive if not strictly subordinated to the

practical conditions and commercial requirements of the times. The

Sirius and Great Western crossed the Atlantic in 1838, and in 1840 the

first ship of the since celebrated Cunard Company made her first

voyage. This was the Britannia, which, with her sister ships, the

Arcadia, Caledonia, and Columbia, kept up the mail service regularly

at a speed of about 8½ knots an hour. The Britannia was 207 ft. in

length between perpendiculars, and 34 ft. 4 in. extreme breadth, 22

ft. 6 in. depth of hold, 423 horse power--nominal--and 1,153 tons

burden, built of wood, and propelled by paddles. In 1860 the Collins

Line started in opposition to the Cunard, and, after a series of

disasters, collapsed in 1858. This was three years after the Persia,

the first Cunarder built of iron, had been completed. In 1850, also,

the Inman Line was started with the City of Glasgow, of 1,600 tons

builders' measurement, and 350 horse power. She was built of iron, and

was the first screw steamer sent across the Atlantic from Liverpool

with passengers, and was the pioneer of the great emigrant trade which

Mr. Inman, above all others, did so much to develop and make cheap and

comfortable for the emigrants themselves, as well as profitable to his

company. That the builders of the celebrated old Great Britain, in

1843, and Mr. Inman, in 1850, should have pronounced so decisively in

favor of the screw propeller in preference to the paddle for ocean

steaming is a proof of their true practical judgment, which time and

practical experience have made abundantly clear. While the Cunard

Company went on developing its fleet from the early wood paddle

steamer Britannia of 1,130 tons in 1840 to the iron paddle steamers

Persia, etc., in 1858, the iron screw steamer China of 1862, to the

still more important screw steamers Bothnia and Scythia, vessels of

4,335 tons, in 1874, the Inman and other lines were as rapidly

developing in speed and size, if not in numbers. The year 1874 is

memorable, for it saw the White Star steamers Britannic and Germanic

put into the water, as well as the Inman steamer City of Berlin and

the two before mentioned Cunard steamers, Bothnia and Scythia. By the

addition of these two ships to their fleet the White Star Line,

although started only in 1870, reached a front rank position in the

New York passenger trade. The author gave in separate tables the logs

of several of these ships, some from published documents and some

kindly furnished by the owners. The Great Western had crossed the

Atlantic from Bristol to New York in 15 days as early as 1838. The

first Cunard steamer, the Britannic, was about the same speed, from 8¼

to 8½ knots an hour. The average duration of the Cunard voyages in the

year 1856 was 12.67 days from Liverpool to New York, and 11.03 days

from New York to Liverpool. The Bothnia, in 1874, reduced the passage

to about nine days. The White Star Britannic, in 1876, averaged 7 days

18 hours 26 minutes outward from Queenstown to New York, and 9 days 6

hours 44 minutes homeward, and has averaged for the last ten years 8

days 9 hours 36 minutes outward, and 8 days 1 hour 48 minutes

homeward. The City of Berlin, of the Inman Line, also built in 1874, 8

days 10 hours 56 minutes, and homeward 8 days 2 hours 37 minutes; and

for the nine years from 1875 to 1883 inclusive, averaged outward 8

days 19 hours 56 seconds, and inward 8 days 8 hours 34 seconds; or,

putting it into rounder figures, the Britannic had reduced the average

passage between the two points to 8¼ days, and the City of Berlin to

8½ days. From the year 1874 on to 1879 no further advance was made in

Atlantic steaming, but in that year the Arizona was added to the Guion

Line, and it soon became evident that another important stride had

been made in the Atlantic passenger trade, which would lead to most

important results. The results, as we all know, have been sufficiently

startling. The Guion Line, which had started in 1866 with the

Manhattan, had now the fastest passenger ship on the Atlantic. In

spite of burning some fifty per cent. more coal than the Britannic,

the ship was an obvious commercial success. The spirited policy which

brought her into existence was appreciated by the public, and the

other lines had to move forward. Then followed a period of rivalry,

the Cunard Company building the Gallia and Servia, the Inman Company

the City of Rome, and the Guion Line the Alaska, all of which were

completed in 1881, and afterward the Oregon for the Guion

Line--1883--the Aurania the same year for the Cunard Company, and,

later still, the America for the National Line, and the Umbria and

Etruria for the Cunard Company in 1885.

[Illustration:

_Frames from outer edge of Tank to Upper Deck, 7 × 3½ × 8/16 for 250

ft. Amidships, for 60 ft. before and abaft these Points 6½ × 3½ × 6/16

at end of Vessel 5 × 3½ × 7/16, all spaced 24 in. apart and all

carried to Upper Deck, double from Bilge to Bilge in way of

Engines.--Frames in Tank on Lattice and Solid Floors, 5 × 3½ × 8/16,

Intermediate Frames, 8 × 4 × 9/16--Rev: Frames, 4½ × 3½ × 8/16,

carried to Upper and Main Deck alternately double, 4½ × 4½ × 8/16 from

Bilge to Bilge in E and B space._

Fig. 2--SERVIA.]

Since the completion of the Etruria, for various reasons there has

been a pause in the tremendous strides made since 1879, and we may

briefly review the results. Taking the Britannic as a standard with

her ten years' average of 8¼ days across, and her quickest passage of

7 days 10 hours 53 seconds, we have now the following steamers of

higher speeds. Taking them in the order of their absolutely fastest

passage out or home, they stand thus:

TABLE I.

---+-------------------------+------+-------+------

| | Days.| Hours.| Mins.

| +------+-------+------

1 | Etruria. | 6 | 5 | 31

2 | Umbria (sister ship). | slightly longer.

3 | Oregon. | 6 | 10 | 35

4 | America. | 6 | 13 | 44

5 | City of Rome. | 6 | 18 | 0

6 | Alaska. | 6 | 18 | 37

7 | Servia. | 6 | 23 | 55

8 | Aurania. | 7 | 1 | 1

---+-------------------------+------+-------+------

It will thus be seen that from the 15 days' passage or thereabout, of

the earliest Atlantic steamers, we had got down in the days of the

Scotia to about 9 days; in the Britannic to 8¼ days, and, at the

present time, we have got to 6¼ days, with seven ships afloat that

have done the passage under seven days, and capable of making their

average passages range between 6½ and 7¼ days.

Ranged in order of gross tonnage, these eight vessels stand as

follows:

TABLE II.

1. City of Rome. 8,144

2. Oregon. 7,375

3. Aurania. 7,269

4. Servia. 7,212

5. Umbria. 7,129

6. Etruria. 7,100

7. Alaska. 6,586

8. America. 5,528

Here the America shows to advantage, for while being eighth in size

she is fourth in point of speed, and from what the author can learn,

although he had no authenticated details on the subject, he believed

she is economical in coal consumption. He might perhaps be permitted

to say that one of the most difficult subjects in connection with the

propulsion of ships on which to get absolutely accurate data is that

of coal consumption. The records of six to eight hours' trials for the

purpose of ascertaining the coal consumption are absolutely worthless,

as all shipbuilders and engineers know, and so far as English ships

are concerned they are never attempted. Foreign owners frequently

stipulate for such trials in their contracts with English

shipbuilders, and get wonderfully economical results on paper, but the

fact that the trials only extend over a few hours renders them

valueless, however carefully the coal may be weighed during that

period. An authentic record of the absolute quantity of coal consumed,

say by each of the eight fastest Atlantic liners, together with their

average indicated horse power on the voyage, for a series of voyages,

would be extremely valuable.

He gave, in Table III., the consumption per indicated horse power per

hour for a number of ships. This table affords valuable data, for it

gives, in addition to the dimensions, the moulded draught of water,

the midship area, the displacement, the indicated horse power, the

speed on trial, the coefficients for the lines both from the block or

parallelopipedon, and also from the midship section prism, together

with the length and angle of entrance obtained by Kirk's rule, the

Admiralty displacement coefficient, together with the coal consumption

per day and per indicated horse power per hour.

[Illustration: Fig. 3--OREGON.]

This table, as will be seen, contains some of the most important of

the Atlantic liners, and also a number of other typical ships, which

will add a variety to its interest and a value to it. The coefficient,

which is contained in the thirteenth column of the table, viz.:

Dis 2/3 × speed³

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

I.H.P. × sqrt(entrance.)

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

generally comes out for ships of similar type more nearly a constant

in the true sense of the word than the corresponding Admiralty

constant. As an example, we have the curves of resistance and horse

power for the City of Rome and the Normandie, a large vessel of 6,000

tons, which the Barrow Company built for the Compagnie Generale

Transatlantique, in which the coefficient of fineness and the form of

the lines pretty closely resemble each other below water; and if we

take from the curves the corresponding speeds and horse powers, and

work out the constants by the two systems, we have at 14 knots the

Admiralty constant for the City of Rome 322.2, and for the Normandie

304.8; and taking for a modified form of constant, the City of Rome

gives 253.7 and the Normandie 251.9, which, as will be seen, are much

closer together. Similarly, at 15 knots the Admiralty constant for the

City of Rome is 310, and for the Normandie 295.2, while a modified

constant comes out for the former at 245, and for the latter 244,

again agreeing almost identically. The same at 16 knots, for the City

of Rome the Admiralty constant comes out 297.6, and for the Normandie

282.8, while a modified constant comes out for the two ships 234.4 and

233.7 respectively, again showing marked agreement. It may be

mentioned that in these two ships the engines are of a similar type,

being three-crank tandem engines, and the propellers have in both

pitch and surface practically the same proportions to the power and

speed. The value of these modified constants will probably be found to

increase as the speeds increase up to the limit and beyond that point

at which wave resistance becomes an important factor.

TABLE III

----------------+--------+---------+---------+-------+-------------+

| | | | | |

----------------+--------+---------+---------+-------+-------------+

| | | | | |

City of Rome | 542 6 | 52 0 | 21 5½ | 1031 | 11,230 |

| | | | | |

Normandie | 459 4 | 49 11 | 19 9¾ | 892 | 7,975 |

| | | | | |

Furnessia | 445 0 | 44 6 | 22 2½ | 893 | 8,578 |

| | | | | |

Arizona | 450 0 | 45 1½ | 18 9 | 758 | 6,415 |

| | | | | |

Orient | 445 0 | 46 0 | 21 4½ | 904 | 7,770 |

| | | | | |

Stirling Castle | 420 0 | 50 0 | 22 3 | 990 | 7,600 |

| | | | | |

Elbe | 420 0 | 44 9 | 20 0 | 807 | 6,350 |

| | | | | |

Pembroke Castle | 400 0 | 42 0 | 17 0 | 648 | 5,130 |

| | | | | |

Etruria | 500 0 | 57 0 | 22 6 | 1090 | 9,860 |

| | | | | |

Aurania | 470 0 | 57 0 | 20 0 | 1020 | 8,800 |

| | | | | |

America | 441 8 | 51 3 | ----- | --- | 6,500 |

| | | | | |

Oregon | 501 0 | 54 2 | 23 8 | 1150 | 11,000 |

| | | | | |

Servia | 515 0 | 52 0 | 23 3½ | 1046 | 10,960 |

| | | | | |

Scotia, P.S. | 369 0 | 47 6 | 19 9 | 867 | 6,000 |

| | | | | |

Alaska | 500 0 | 50 0 | 21 0 | 949 | 9,210 |

| | | | | |

Aller | 438 0 | 48 0 | 21 0 | 907 | 7,447 |

| | | | | |

Ems | 430 0 | 46 10 | 20 7½ | 877 | 7,030 |

----------------+--------+---------+---------+-------+-------------+

----------------+----------+---------+-----------+-----------+-----------+

| | | | | |

----------------+----------+---------+-----------+-----------+-----------+

| | | | | |

City of Rome | 11,890 | 18.235 | .649 | .925 | .702 |

| | | | | |

Normandie | 6,959 | 16.66 | .614 | .901 | .681 |

| | | | | |

Furnessia | 4,045 | ¹14 | .682 | .903 | .755 |

| | | | | |

Arizona | 6,300 | 17 | .589 | .895 | .658 |

| | | | | |

Orient | 5,433 | 15.538 | .621 | .919 | .676 |

| | | | | |

Stirling Castle | 8,396 | 18.4 | .569 | .889 | .639 |

| | | | | |

Elbe | 5,665 | 16.571 | .591 | .901 | .655 |

| | | | | |

Pembroke Castle | 2,435.8 | 13.25 | .623 | .623 | .692 |

| | | | | |

Etruria | 14,321 | 20.18 | .538 | .896 | .637 |

| | | | | |

Aurania | 8,500 | ¹17.5 | .575 | .942 | .632 |

| | | | | |

America | ----- | ¹17.8 | ---- | ---- | ---- |

| | | | | |

Oregon | 13,300 | 18.3 | .599 | .849 | .67 |

| | | | | |

Servia | 10,300 | ¹16.9 | .610 | .862 | .71 |

| | | | | |

Scotia, P.S. | 4,632 | ¹14.31 | .605 | .92 | .65 |

| | | | | |

Alaska | ----- | ---- | .614 | .904 | .679 |

| | | | | |

Aller | 7,974 | 17.9 | .590 | .899 | .656 |

| | | | | |

Ems | 7,251 | 17.55 | .593 | .907 | .652 |

----------------+----------+---------+-----------+-----------+-----------+

----------------+------------+-----------------+-----------------+

Name. | D 2/3 × S³ | D 2/3 × S³ | Kirk's system. |

| ---------- | --------------- | |

| I.H.P. | _____ +---------+-------+

| | ------- |entrance.| |

| | 10 | | |

----------------+------------+-----------------+---------+-------+

| | | | |

City of Rome | 255 | 201.3 | 161.27 | 8° 29'|

| | | | |

Normandie | 265 | 219.5 | 146.41 | 8° 44'|

| | | | |

Furnessia | 284 | 273 | 108.7 |10° 28'|

| | | | |

Arizona | 269.2 | 217 | 153.79 | 7° 30'|

| | | | |

Orient | 270.8 | 225 | 144.17 | 8° 21'|

| | | | |

Stirling Castle | 286.8 | 233.7 | 151.3 | 8° 22'|

| | | | |

Elbe | 275.5 | 229 | 144.6 | 7° 56'|

| | | | |

Pembroke Castle | 284 | 258 | 122.9 | 8° 49'|

| | | | |

Etruria | 260 | 191.8 | 184 | 6° 52'|

| | | | |

Aurania | 266 | 204.6 | 170 | 8° 38'|

| | | | |

America | --- | --- | --- | ----- |

| | | | |

Oregon | 227.9 | 190 | 164.3 | 9° 39'|

| | | | |

Servia | 231 | 192 | 145.3 |10° 42'|

| | | | |

Scotia, P.S. | 208.9 | 186 | 126.8 |13° 21'|

| | | | |

Alaska | --- | --- | 160.23 | 8° 2'|

| | | | |

Aller | 277 | 225 | 150.6 | 8° 10'|

| | | | |

Ems | 273 | 223 | 149.4 | 8° 40'|

----------------+------------+-----------------+---------+-------+

----------------+------------+--------------------+----------------+--------+

|-----+------+-------------+------+--------+-------+ |

| Per | Per | Diameter |Stroke|Heating | Bar | |

| day |I.H.P.| | |surface |surface| |

| | | | | | | |

----------------+-----+------+-------------+------+--------+-------+--------+

| | | Ins. | Ins. | | | lbs. |

| | |/3 @ 46 \| | | | |

City of Rome | 185 | 2.2 |\3 @ 86 /| 72 | 29,286 | 1398 | 90 |

| | | | | | | |

| | |/3 @ 35-7/16\| | | | |

Normandie | 148 | 2 |\3 @ 74-7/8 /| 67 | 21,404 | 756 | 85.2 |

| | | | | | | |

Furnessia | 97 | 2.2 | 49-100 | 66 | 10,396 | 440 | 90 |

| | | | | | | |

| | |/1 @ 62 \| | | | |

Arizona | --- | --- |\2 @ 90 /| 66 | ---- | ---- | 90 |

| | | | | | | |

| | |/1 @ 60 \| | | | |

Orient | --- | --- |\2 @ 85 /| 60 | ---- | ---- | 75 |

| | | | | | | |

| | |/1 @ 62 \| | | | |

Stirling Castle | --- | --- |\2 @ 90 /| 66 | 21,161 | 787 | 100 |

| | | | | | | |

| | |/1 @ 60 \| | | | |

Elbe | --- | --- |\2 @ 85 /| 60 | ---- | ---- | --- |

| | | | | | | |

Pembroke Castle | 44 | 1.7 | 43 and 86 | 57 | 7,896 | 288 | 99 |

| | | | | | | |

Umbria and | | |/1 @ 71 \| | | | |

Etruria | 315 | 2.1 |\2 @ 105 /| 72 | 38,817 | 1606 | 110 |

| | | | | | | |

| | |/1 @ 68 \| | | | |

Aurania | 215 | 2.2 |\2 @ 91 /| 72 | 23,284 | 1001 | --- |

| | | | | | | |

| | |/1 @ 63 \| | | | |

America | 185 | --- |\2 @ 91 /| 66 | ---- | 882 | --- |

| | | | | | | |

| | |/1 @ 70 \| | | | |

Oregon | 310 | 2.2 |\2 @ 104 /| 72 | 38,047 | 1428 | 110 |

| | | | | | | |

| | |/1 @ 72 \| | | | |

Servia | 205 | 2 |\2 @ 100 /| 78 | 27,483 | 1014 | --- |

| | | | | | | |

Scotia, P.S. | 168 | 3.4 | | -- | ---- | ---- | --- |

| | | | | | | |

| | |/1 @ 68 \| | | | |

Alaska | --- | --- |\2 @ 100 /| 72 | ---- | ---- | 100 |

| | | | | | | |

| | |/1 @ 44 \| | | | |

Aller | --- | --- ||1 @ 70 || 72 | 22,630 | 799 | 150 |

| | |\1 @ 100 /| | | | |

| | | | | | | |

| | |/1 @ 62 \| | | | |

Ems | --- | --- |\2 @ 86 /| 60 | 19,700 | 780 | 100 |

----------------+-----+------+-------------+------+--------+-------+--------+

¹Mean speed of a voyage across the Atlantic Ocean.

The author next considered the strains to which a ship is exposed, and

stated that he had before him the calculations for three of the

largest vessels, two of them of iron and the other of steel; and he

found, in the case of the iron, the maximum tension on the gunwale

during the greatest hogging strains likely to be endured at sea would

not exceed about six tons per square inch, while in the case of the

steel ship it is only about 6½ tons. These strains are well within the

limits of safety, and a comparison of the scantlings of these with the

others justifies the assertion as to their general safety from a

structural point of view. The sections of these three ships are shown

in Figs. 1, 2, and 3, with their principal scantlings. It will be seen

from these sections that the three ships differ materially in their

mode of construction. In the case of Fig. 1, which represents the City

of Rome, the largest of the three, it will be seen that the main

framing of the vessel is entirely transverse, with very heavy keelsons

in the bottom, and large partial bulkheads or web frames, and the

outside plating arranged on what is termed the edge to edge principle,

with a great portion of it double. In the next section, Fig. 2, the

Servia, which is built of steel, on the other hand, the bottom is

built on the longitudinal cellular system, the first application, he

believed, of this system to an Atlantic liner. The plating of the

Servia is of the usual alternate outer and inner strake system, partly

double; while the third section, the Oregon, approaches more nearly to

the ordinary system of framing and plating usually adopted, but it

will be seen that she was well tied in the bottom by very heavy

intercostal and plate keelsons, as well as in the top by heavy

stringers and sheer strakes, with much of her plating doubled, and

heavy web frames inside. The author next considered the question of

stability, and went on to deal with the subject of twin screws, and

stated that the Barrow Shipbuilding Company has done more in the way

of planning and designing for the adoption of twin screws lately than

for any other mode of propulsion, and this chiefly for passenger

steamers. He did not attach much importance to the particular form of

the blade either in single or twin screws, as he believed so long as

the disk area, the surface, and pitch were properly adjusted to the

speed of the vessel, and to enable the engines to use, at the maximum

speed, just the full quantity of steam that the boilers can make, we

have got pretty nearly as far as we can get. To fix these dimensions

of the propeller accurately at the present time, and without further

knowledge of the action of the screw on the water, was, he thought,

impossible. All the rules and formulæ are empirical. The best one he

knew is given in Table IV., due to Mr. Thom, the head of the Barrow

Company's engineering drawing office, and at present acting manager,

who has used it for some years in practice. These formulæ are based

upon the assumption that the area of propeller disk should be

proportional to the indicated horse power, divided by the cube of the

speed, and the same with the projected area of the propeller and also

the surface.

TABLE IV.

_Particulars of Propellers and Constants._

------------------------------+-------+---------+----------+--------------

| Length| | Proj. | Feet per

Ship. | of | Disk | surf. | minute.

| ship. |constant.| constant.|Speed of tips.

------------------------------+-------+---------+----------+--------------

City of Rome. | 542 | 220 | 69 | 4,715

Normandie | 459 | 250 | 66 | 4,099

Furnessia | 445 | 223 | 69 | 3,654

Eden | 300 | 211 | 64 | 3,080

Yorouba | 270 | 213 | 63 | 3,202

Taygete | 260 | 238 | 56 | 3,166

Kow-shing | 250 | 171 | 69 | 3,369

S.Y. Monarch | 152 | 221 | 65 | 4,040

S.Y. Aries | 138 | 179 | 56 | 2,986

Twin screw Fenella | 200 | 244 | 64 | 2,890

Twin screw H.M.S. Fearless[2] | 220 | 277 | 67 | 5,022

Twin screw H.M.S. Iris | --- | 454[6]| 135[6] | ---

Twin screw H.M.S. Iris [3] | 300 | 412 | 221 | ---

Twin screw H.M.S. Iris [4] | 300 | 346 | 99 | 4,961

Twin screw H.M.S. Iris [5] | 300 | 439 | 82 | 5,309

------------------------------+-------+---------+----------+-------------

[Footnote 2: Estimated with a speed of 17.5 knots and 3,370

I.H.P.]

[Footnote 3: With the first propeller at the estimated speed of

17.5 knots and 7,000 I.H.P.]

[Footnote 4: With four bladed modified Griffith's on actual

trial.]

[Footnote 5: With two bladed modified Griffith's on actual trial.]

[Footnote 6: Constants obtained from first propeller calculated

from a speed of 18.5 knots and 7,500 I.H.P.

Area of propeller disk × speed of ship in knots.³

Disk constant = --------------------------------------------------

I.H.P.

Projected Projected area of propeller × speed of ships in knots.³

area = ------------------------------------------------------

of constants I.H.P.

Expanded area constants may be obtained and used in the same way.]

The author said that he hoped to bring before the meeting impartially