ON RIVER STEAMERS. 279 
essentials of river navigation, the weight of the vessel must be calculated with 
the greatest care and minuteness. 
54. In the estimates received by the Assam Company for an iron tea-boat 
of 75 feet in length and 12 feet in breadth, the weight of the hull appeared 
to vary from 17 tons to 10 tons. Much of this was, no doubt, attributable 
to variations in the thickness of the metal plates, prepared by different me- 
thods of construction. 
55. Tenders were sent to the office in the usual routine, and others were 
requested by the Directors from experienced shipbuilders submitting a spe- 
cification, and to some a tracing of the best boat employed by the Company, 
with suggestions for increasing the length from 68 to 75 feet, with fittings 
adapted to navigation by native crews. The five tenders received for the 
iron hull packed for shipment varied from £300 to 72 per cent. increase of 
cost, the former being the net price contracted for, the latter a price per 
ton, builders’ measurement, and not including pumps and capstan, these 
admitting of an indefinite extra charge. The cost of the same vessel by the 
twe contractors would differ 100 per cent. 
Having issued the construction form of tender, with specification, and 
calculated quantities of displacement, weights, and capabilities for cargo, 
they were verified and reconsidered, after consultation, by several experienced 
shipbuilders, so as to secure a very great reduction in the weight of the hull, 
and consequent increase of cargo at light draft: the contract price of different 
builders only varied 4 per cent. The amended specifications also reduced 
the weight of hull 25 per cent., increasing the capability for cargo at 2 feet 
draft 50 per cent. 
57. From careful observation, there are many experienced shipbuilders 
and naval architects who are now competent to undertake contracts, not as 
formerly, by register tonnage and nominal horse-power at so much per ton 
of register, but in terms of capability and speed. Such we know to be the 
case, and with admirable results, in Liverpool, London, the Clyde, and 
other ports. 
58. The exceeding diversity of opinion, and the anomalies of practice, 
with regard to the requirements of steam-ships and mode of contracting for 
them, may be accounted for by the fact, that the sudden demand for iron 
steam-vessels called into existence a numerous body of what may be termed 
Mushroom Marine Engineers, who had previously been employed as assistants 
to engineers, boiler-makers, or contractors. It is to such men that we are 
indebted for the luminous discussions on the “ Formula ” of resistance, power, 
and speed of steamers, one of whom propounded as a fixed prineple, that 
naval architects had nothing to do but provide displacement at a given area 
of section, and that the speed did not depend on the form or lines of the 
vessel ; also that displacement or friction of bottom very little affected the 
resistance. 
59. To such extent has this vague and indefinite style of reckoning pro- 
ceeded, that there seems to be almost double entendre in everything con- 
nected with the specification and contracting for steam-vessels. In the first 
place, there are two meanings attached to the term “tonnage,” the old and 
the mew; then the engine-power is reckoned in nominal and effective horse- 
power; and the discrepancy which exists between these last-named quan- 
tities is scarcely greater than what is found between the net contract price, 
and that which, under accumulated impositions, might come under the name 
of the commission price. 
Steam Navigation in England.—The tabular system adopted of estimating 
