TRANSACTIONS OF THE SECTIONS. 
153 
actnllv realized on the several seas traversed by our steamers. An abstract of the 
molt 'was exhibited in a tabular form, showing the comparative tonnage, bulk, 
iwnsions, displacement and resistance, and other particulars, ot vessels built or 
feigned for the various services and seas to which navigation is extent mg. 
By reference to these results, and the diagram of the midship section, an approxi- 
estimate may be made of their relative form, resistance, bulk, or capabl i \ or 
•mating the ocean. In the upper lines of the table were found the tonnage, 
iomsions and proportions of mast of the curliest ocenn steamers constructed by 
r^-nent builders, with the actual speed realized by them on mail service, some ex- 
'r-ine over six years, and all over many thousand miles. This information, from 
“Soil returns between 1845 and 1851, shows thut on an aggregate of 1 , 2 < 1,000 
the realized speed only averaged 7‘945 knots per hour in the Mediterranean 
ud Indian Seas. The general average of the earliest steamers on the West Indian 
"*was even below'this, while the earlier vessels placed on Mr.Cunard's line realized 
1 knots. 
As to the relative speed of different vessels, it was seen in the last column that the 
fcD ?th of the live steamers that realized 850 knots per hour averaged less than six 
7 * their breadth, whilst those that realized less than 7 *&t* hoots averaged upwards 
' wn times their breadth. The form being as important to speed as the propor- 
•Mne midship sections of several of these were given in the diagrams. Ihree on 
-hand side—the - Great Western,* * Precursor.’ and * India/—may br con- 
,1 . r t., type Of the original large ocean steamers built on the Avon and Clyde ; 
2 James,’*Oriental/ and * Hindostan’ representing those huilt on the Iharaea 
. erse y- hi the absence of actual sections, the form of the latter, and other 
3 '. ,na >' lje approximated to by reference to the columns of the table, by which 
be ** a that these timber steamers have all extremely flat floors and straight 
atm'ofK T of coa siderable depth. The diagrams as well as the tables show the 
jO* breadth to depth and length, and the ratio of displacement to area of section, 
'Huru lhird . and two-thirds the height of deck, affording a lair criterion of 
The aJlc and resia t®nce of different vessels. 
1 a# sectinn, «.<■ ... . . ... .. r« .. ...._,eio ‘ Pre- 
rars or at ^. e ' hireat Western/ built by Mr. Patterson i 
I 439 Napier in 1841, and the ‘ Comprehensive/ design* 
bring R'SQ * 0 — at similarity in form and rise of floor, their pr 
in 1838, the 
designed by the author in 
c imilarity in form and riBe of floor, their proportion of length 
thr^ :3 b ‘ 08 - and fi-71 breadths respectively j the relative tonnage of these 
their le n !J er9 , bcin B 1242, M?(i, and 2015 tuns by the old law, a* deduced from 
Criterion 6 0 ‘„ and breadth, without reference to the depth, thereby affording no 
Th e , nrnn' eir . re * at * ve bulk or displacement. . . 
to and W m ° < ; 0 , re P resen ts a class of very large paddle steamers, built of oak tim¬ 
'd. knot. 8 rr P u ank >8' with great steam power, for the West India mail service, of 
^»^/ e 1 M 0,ent '’ for the same service, is built of three thicknesses of plank, 
j. t0 nghtness and speed. It is well known that some of these very long 
* n,Jr mou8. Pr ° Ved deficient in strength, and that their consumption of coal is 
aQd 'Arabia’ represent the improved North American mail steamers of 
V s 52 av» P ,,i | cy are built of timber, and their average speed in fifty-four voyages 
D| 'Aralii-• ra, ' ler more than lOi knots an hour. The ratio of length to breadth 
^crably nir^ and 0,ber tirQ her vessels is about 7*00 breadths, but they have con - 
2400 ton riSe . 0 ^ door and finer lines than the earlier vessels, their size being 
°. ld or bu ilder*a measurement. , 
llr ** 1)81^ ' N St t an ' er ' Arctic’ represents the class of vessels known as Collins s 
are all bulb <■ • k ftnd Liverpool; they are said to have averaged eleven knots, 
^ of the Cunaol p luib ® r °f very heavy scantling. Their tonnage is^greater^than 
and 
53 by 
excellent sea-boat. 
breadVl ~* " 1C t iec “ l,ar lonn of the ' tire at mitain shows a very flat floor 
, , with a rise from floor to main breadth, and rounded home side 
a* fV, 1 a * »utu su'diiit isi, nave u. jhujiu 
» “7 mtter, the broadest, being spoken of as an 
"ith tke breadth 8 * ‘i, P ec ? r,ar T° rm of the ‘ Great Britain’ 
i J / 1 * light d a rise from floor to main breadth, anu rounueu uumc 
to breadth ' °* Wa ^ cr » the tonuage is about 3400 tons, and her ratio of 
is 5’78. The lareest and loncrest vessel vet constructed is the 
