MERCANTILE STEAM TRANSPORT ECONOMY. 427 



Wrights and engineers, felt themselves constrained to meet their rivals in 

 trade with their rivals' M'eapons ; numerous devices have been adopted with 

 a view to the development of power on board of ship by packing the greatest 

 amount of engine-power into the least space, and undoubtedly great improve- 

 ments have been made by adapting the dimensions and proportions of vessels 

 to the service required, but still " Fame," in regard to the character of steam- 

 ships based on speed, has been too much the result of horse-power delusive 

 jockeyship rather than of truthful science. By the practice of trade, horse- 

 power came to be measured by the diameter of the cylinder, without any 

 limitation as to the capabilities of the boiler, and gradually in time a marine- 

 engine contract was considered not to be fulfilled unless the engines were 

 capable of working up to an "indicated horse-power" at least double that of 

 the contract nominal power; still, however, no specific limit was assigned 

 either by custom or by law ; and at length to such a degree has competition 

 set truth at defiance, that the working, or " indicated horse-power " of 

 engines delivered under contract, has frequently amounted to four times the 

 nominal horse-power actually stipulated for by the contract. These facts 

 are fully set forth in the paper read by me before the Society of Arts on the 

 16th of May, 1855. 



Having thus pointed out the indefinite application in steam-shipping 

 practice of the terms " tonnage" and "horse-power," with reference to the 

 definite terms " displacement " and " indicated horse-power," it may be still 

 further edifying that we illustrate the anomalies liable to result when these 

 terms are used in combination with each other, as is constantly the case in 

 expressing and recording the ratio of tonnage to power of a steam-ship. In 

 exposition of this matter, I may again refer to the before-mentioned paper, 

 whereby it will be seen that I selected ten vessels, in each of which the ratio 

 of builders' tonnage to nominal power was very nearly the same, namely, in 

 the ratio of 100 tons of builders' tonnage to 40 nominal horse-power, or 

 2^ tons of tonnage to one nominal horse-power; but on comparing the 

 constructors' load displacement of these same ships, calculated in tons weight 

 at 35 cubic feet of water to the ton, with the effective working power, based on 

 indicator measurement, the ratio was found to be 100 tons displacement to 

 38 horse-power in one case, and 100 tons displacement to 281 horse-power 

 in another. 



The recorded statistics of these ten vessels would lead one to infer that 

 they are all powered in the same proportion of engine-power to size of ship ; 

 but, in fact, they are all different, and on comparing the two extremes, one 

 ship has no less than seven times the power of the other, in proportion to 

 size of ship as determined by displacement. In fact, generally, the records 

 of register-tonnage and nominal horse-power do not constitute statistical data 

 of any value whatever for the scientific purpose of discriminating between 

 the relative dynamic n orits of steam-ships, but, on the contrary, such records 

 and all ideas resulting therefrom are positively delusive and mischievous. 

 The conclusion at which 1 would arrive from these statements is, that the 

 very first step in any attempts to bring steam affairs within the range of 

 arithmetical calculation, must necessarily be to establish the measure or value 

 which we assign to our units of tonnage and power. It is only by the moral 

 influence of such a body as the British Association that the cause of science 

 can obtain a hearing in this matter of statistical registration applied to ship- 

 ping. With reference to our units, it is, of course, desirable that the measure 

 of the unit, to be legally recognized as the unit of power, should be nearly 

 in accordance with the general average of practice at the time when the unit 

 may be so established; and as at the present time (1856) the gen«ral run of 



