ON THE MEASUREMENT OF SHIPS FOR TONNAGE. _— ‘81 
gallon, or the statute ton weight. A legalised statute unit of power is a 
positive requirement of the age. It is not proposed that there shall be any 
obligation as to engines being worked up to the full power that they are 
capable of developing, any more than that ships shall not put to sea without 
being fully loaded. 
G. It is further submitted that the deficiencies of the Act of “1854,” in 
respect of the defective registration above referred to, vitiate the public 
statistics of the country so far as based on the registration of shipping ; for, 
as shown in the foregoing pages, the ratio between the registered tonnage 
-of a ship, and its capability for safely carrying weight of cargo, depends in 
great measure on the dimensions or proportions of length, breadth and depth 
of theship ; so much so, that (as shown) a ship of 2000 tons register may be 
so proportioned as to have no displacement available for cargo without 
encroaching on the freeboard necessary to the safety of the ship, whilst an- 
other ship may be so proportioned externally and constructed internally as 
to carry safely the double of her registered tonnage, especially in the case 
of auxiliary powered steam-ships, which now threaten to supersede sailing 
ships altogether. Hence the mere registered tonnage of ships is not of itself 
a statistical criterion of the extent of trade, excepting in so far as respects 
the carrying power of similarly proportioned and similarly built vessels. 
7. Registration under the Act of “1854” does not meet the requirements 
of commercial operations, as shown by shipping advertisements, which fre- 
quently ignore the legalised registration under the Act of “1854,” and refer to 
other designations of tonnage, such as gross tonnage, tons burden, tonnage 
O.M., tons (without designation), all which terms are made use of irrespec- 
tive of the register ton, and not one of all these five terms for tonnage 
expresses or has any constant ratio whatever to the one thing needful, namely, 
the tons weight of cargo that a ship will carry with reference to any statute 
gauge mark. Then, again, we see engines advertised as 100 H.P. nominal, 
but 450 H.P. effective, and neither nominal H.P. nor effective H.P. have 
any statute signification or definite ratio to each other. 
_ 8. The Act of “1854” in respect of its registration deficiencies, is obstruc- 
tive of the application of science to maritime engineering and architecture, 
as respects all investigations into the comparative dynamic performances of 
steam-ships as a means for practically determining the best type of form for 
the respective purposes or services for which ships may be required. The 
extent to which this exclusion of science for so important a part of naval 
engineering and architecture as that of developing the dynamic economy of 
different types of ships, is adverse to public interests, may be judged of from 
the fact, that on estimating the comparative dynamic capabilities of ships of 
given size, and required to steam at a given speed, but of different types of 
form, by any recognised law of scientific comparison, a vast difference of 
dynamic merit is found to be prevalent. The great majority of ships are 
found to be of a low order of dynamic merit, below what has been found to 
be practically realisable; so much so, that the average of the generality of 
shipping requires probably 25 per cent. more power to attain a given speed 
than is required (ceteris paribus) by vessels of the superior type, which is 
occasionally produced ; and when it is considered that the trade and navi- 
gation returns for “1856” show that the foreign import and export trade of 
Great Britain, as indicated by the registered tonnage of shipping, amounts to 
18 millions of tons per annum, whilst the home trade amounts to 26 millions, 
_ being a total of 44 millions of tons per annum, sea-borne trade (that is, if 
_ the weight-carrying capability of ships be on the average equal to the 
— tonnage), and as the cost of all merchandise to the consumer, 
* G 
