112 D2 REPORT—1857. — ‘ an?r vO 
CRUSTACEA. 
Dredged by Mr. Thompson in September 1851, in 4 to 6 fathoms, near Ring- 
dufferin and Ringhaddy Islands ; most of these were also got in June 1857 :— 
Stenorhynchus phalangium. Eurynome aspera. Porcellana longicornis. 
Inachus Dorsettensis. Portunus pusiilus. Galathea squamifera, 
dorynchus. arcuatus. Hippolyte varians. 
Hyas araneus. Pagurus Bernhardus. 
SpronGEs or STRANGFORD LouGH. 
These were mostly all got in one locality, upon oyster and scallop beds, 
in about 20 fathoms, near the centre of the expanded part of the Lough, 
between Killinchy and Kirecubbin. These were long since dredged by 
Messrs. Thompson and Hyndman, and nearly all were found in 1857 :— 
Tethya lyncurium. Halichondria hirsuta. Cliona chelata. 
Halichondria hispida. —— suberea. Grantia lacunosa. 
fucorum. mammillaris. fistulosa. 
—— sanguinea. carnosa. Dysidea fragilis. 
macularis. 
Suggestions for Statistical Inquiry into the extent to which Mercantile 
Steam Transport Economy is affected by the Constructive Type of 
Shipping, as respects the Proportions of Length, Breadth, and 
Depth. By Cuarues ATHERTON, Chief Engineer of Her Majesty’s 
Dockyard, Woolwich. 
Ar the Cheltenham Meeting of the British Association in August 1856, I 
had the honour to present a paper on “ Mercantile Steam Transport Economy.” 
The principal objects of that paper were, in the first place, to expose the 
difficulty which attends all investigation and even all discussion on maritime 
affairs, in consequence of the technical terms in which shipping, especially 
steam shipping, is spoken of, and officially registered as respects the size or 
magnitude of vessels and machinery, having no definite meaning expressive 
of the capability of ships for carrying weight of cargo, or the capability of 
the machinery for the production of working power; and in the second place, 
after getting the better of the foregoing difficulty by rejecting the records of 
tonnage and nominal horse-power as being indefinite, and basing my calcu- 
lations on load displacement, as expressing the actual magnitude and weight 
of the mass propelled through the water, and assigning an arbitrary but defi- 
nite amount of working power based on indicator measurement to the term 
horse-power, and availing myself of maritime statistics already published as 
to the actual performances of vessels, and of the received laws which are re- 
cognized as expressing the mutual relations of displacement, power, and speed 
under definite conditions of practical application, I was enabled to demon- 
strate approximately the proportional increased rate of pecuniary cost which 
attends an increased rate of speed at which cargo per ton weight may be con- 
veyed by steam-ships of any definite size and type, according to the length 
of passage and speed that may be required: for example, assuming a passage 
of 3250 nautical miles to be performed by a vessel of 2500 tons load dis- 
placement, and of which the coefficients of dynamic duty were assumed to be 
known and equal, and of a comparatively high order, the vessels respectively 
being fitted for speeds of 8, 10, and 12 knots per hour, it was shown that the 
cost of transport per ton weight at the speed of 12 knots per hour would be 
about 50 per cent. above the cost that would be incurred by a speed of 
10 knots, and about 100 per cent., or double the cost incurred by a speed of 
SS Ss ll 
SS ee ee 
:— 
