MERCANTILE STEAM TRANSPORT ECONOMY. 435 



or neglect of its working condition, may be exposed, correction will follow, 

 the directorial management of steam-shipping affairs, as respects steam-ship 

 capability, will be based upon arithmetical calculation, thereby prosecuting 

 its assigned service with confidence, and rejecting all Utopian projects that 

 will not pay. Thus science will produce its fruit in promoting public in- 

 terests, without detriment to the fair competitive pursuits of any class, by pro- 

 ducing a sound, well-understood, and healthy condition of steam- ship manage- 

 ment, and consequently of " Mercantile Steam Transport Economy." 



Remarks by James R. Napier, Glasgow, on Mr. Atherton's Paper on Mer- 

 cantile Steam Transport Economy, 

 I quite agree with Mr. Atherton in regard to the indefiniteness of the 

 term horse-power as at present used in steam-engine contracts, and in the 

 desirableness of having a dynamical unit, or standard of power or work 

 legalized, as well for the purpose of buying and selling machines produ- 

 cing power, as for that of scientific comparison. The rule or formula 

 established by James Watt for the horse-power of condensing engines was 

 P X V foot lbs. per minute , , , ^^^ , 



SSmo^^ 33 000 ~ horse-power, where the pressure (P) and 



velocity (V) had either their ac<?^a^ values or fractional parts thereof. But 

 at the present time the pressure (P) is continued at what it was in the days 

 of Watt, viz. 7 lbs., no matter what the actual pressure may be now. And 

 for the velocity (V) almost every engineer has a scale of his own, varying 

 according to the length of stroke of the steam-piston ; some assuming the 

 velocities to vary as V (of the length of stroke), others following the Admi- 

 ralty rule for paddle engines assuming the velocities to vary as \/ (of the 

 length of stroke). All these assumptions, moreover, have no necessary con- 

 nexion with the results desired, nor with the actual results afterward obtained ; 

 nor do they answer any better the purpose either of the buyer or seller ; and 

 all the use they subserve is to fix the size of the cylinder by the very round- 

 about method of resolving an arithmetical or algebraical equation in which 

 two of the three quantities, diameter, length of stroke or velocity, and horse- 

 power required to be known. 



As the term horse-power applied to steam-engines was fixed by Watt at 

 33,000 lbs. raised 1 foot high per minute, and as this same value is used by 

 the Americans, the French, the Germans, and, I presume, by all nations 

 where the history of the steam-engine is known, I should be very sorry to 

 recommend any change as to the use of the name in any other sense than as 

 synonymous with 33,000 lbs. per minute. I see no objection, however, to 

 the entire abolition of the term Nominal Horse-Power, as it is of no use 

 whatever to the engineer, as little to steam-engine owners, and deceitful to 

 the public. 



As I adhere to 33,000 lbs. per minute being received as a horse-power, I 

 would object to the 33,000 being altered into 132,000, or into any other 

 figure, without at the same time changing the name into something alto- 

 gether different from Horse-Power or Marine Horse-power. I would sug- 

 gest that the power be expressed in foot lbs. alone, as this is a term already 

 known to all scientific nations. Dividing by 1,000,000, the result would be 

 simply stated in millions of foot lbs. 



As to the tonnage question, I feel I know very little about it, except that 

 the present law is very complex, and certeunly does not give what Mr. 

 Atherton would like, viz. the displacement. 



That part of Mr. Atherton's paper concerning the comparison of vessels 



2f2 



