362 



NATURE 



[August 14, 1890 



that the Institution of Civil Engineers did in fact promote 

 science :— 



" Substantially, as it seems to me, the whole of the 

 Society's income is applied to the promotion of science. 

 My Lords, I cannot conceive in what better way the pro- 

 motion of mechanical science, and in particular of those 

 branches of mechanical science which lie within the 

 province of civil engineering, could be effected. I cannot 

 doubt that by means of the discussions on the papers 

 read at the ordinary meetings of the Society much new 

 light has been thrown on scientific questions, and much 

 knowledge, which would otherwise have perished, has 

 been preserved. I see no trace of a selfish or illiberal 

 spirit in the proceedings of the Society, nor do I find any- 

 thing to lead me to suppose that its property and income 

 are applied otherwise than bona fide for the promotion of 

 science. The action of the Society may incidentally 

 benefit the profession to which its members belong — I 

 have no doubt that is so— but I agree with the Master of 

 the Rolls in thinking that ' that which this Society does 

 is something higher and larger than the mere education 

 of students and others for the profession of civil 

 engineers.' " 



The admirable definition of the object of the Institution, 

 embodied in the charter of 1828, was stated in the course 

 of one of the judgments to have been drafted by Thomas 

 Tredgold. The Institution, it says, is established for the 

 purpose of 



" the general advancement of mechanical science, and 

 more particularly for promoting the acquisition of 

 that species of knowledge which constitutes the pro- 

 fession of a civil engineer, being the art of directing 

 the great sources of power in nature for the use and con- 

 venience of man, as the means of production and of 

 traffic in States both for external and internal trade, as 

 applied in the construction of roads, bridges, aqueducts, 

 canals, river navigation, and docks, for internal inter- 

 course and exchange, and in the construction of ports, 

 harbours, moles, breakwaters, and lighthouses, and in the 

 art of navigation by artificial power for the purposes of 

 commerce, and in the construction and adaptation of 

 machinery, and in the drainage of cities and towns." 



It is only right to say, in conclusion, that the utility of 

 the work done by the Institution was admitted in the 

 warmest manner by those judges who found themselves 

 compelled to decide against its claim to exemption, now 

 happily established. 



PRINCIPLES OF ECONOMICS. 

 Principles of Economics. Vol. I. By Prof. Alfred Mar- 

 shall. (London: Macmillan and Co., 1890.) 

 ECONOMICS admit of being reduced to principles 

 more than other sciences dealing with human 

 actions, for the reason which Prof. Marshall has thus 

 expressed: "Wide as are the interests of which the 

 economist takes account when applying his doctrines to 

 practice, the centre of his work is a body of systematic rea- 

 soning as to the quantitiesof measurable motives." These 

 measurable motives are not necessarily self-interested : 

 '' The range of economic measurement may gradually 

 extend to much philanthropic action." Even now the supply 

 of labour and of capital is largely due to the motive of 

 family affection. The uniformities of action resulting 

 from such measurable motives may be regarded as the 

 laws of motion in what Jevons called the mechanics of 

 NO. 1085, VOL, 42] 



industry— z. science which Prof. Marshall has cultivated 

 with more success than any of his predecessors, owing to 

 an unexampled combination of antithetical powers, the 

 comprehensive grasp of mathematical reasoning, and the 

 careful handling in detail of the observed facts. 



As in physical mechanics innumerable conditions may 

 be comprehended under the principle of virtual velocity, 

 so also there is a unifying principle in the mechanics of 

 industry. " Most economic problems have a kernel re- 

 lating to the equilibrium of dertiand and supply." It is 

 the peculiar merit of Prof. Marshall's arrangement to 

 treat the law of supply and demand generally, before 

 applying it to particular " markets," such as that relating 

 to labour. It is here that he differs most from Mill, who 

 seems to put asunder what the nature of things has 

 joined together under one law — distribution and exchange^ 

 If Prof. Marshall's conception does not come as a surprise 

 to his readers, it must be considered that he himself, in 

 published and unpublished writings, has prepared the 

 scientific world to accept his view. The services of 

 others, particularly Prof. Walras, in improving upon the 

 old wooden conception of distribution are not to be for- 

 gotten. Still it is true that, as far as we know. Prof. 

 Marshall is the first adequately to treat what he has else- 

 where called the pure theory of domestic (as opposed to 

 international) value ; uniting in a comprehensive view 

 the doctrine of final utility, which Jevons and other 

 recent writers have made prominent, with the equally 

 eternal verities relating to " cost of production," which 

 are connected with the name of Ricardo. The " theorems 

 of Ricardo and Marshall " are rightly coupled by Signor 

 Pantaleoni in his masterly " Principii di Economia Pura."^ 



The relation between cost of production and demand 

 is thus expressed by Prof. Marshall, following Cournot. 



X 



In the annexed diagram the abscissa indicates the 

 amount of a product, and the ordinate the price thereof. 

 dd' is the demand curve, representing the quantity of the 

 product which is demanded at each price ; SS' the supply 

 curve, representing the quantity which is offered at each 

 price. The intersection of these curves determines the 

 equilibrium of the market — a generic term used in a wide 

 sense, covering the temporary equilibrium of a fish-market 

 and those slow processes of competition which it requires 

 a generation to work out. 



From this point of view is apparent the inaccuracy of 

 those who describe value as altogether an affair of final 

 utility, and speak of Ricardo as being " preposterous " in 

 the classic sense of putting the cart before the horse. 

 To use our own illustration, these economists might be 

 compared to a physicist who should insist that in the 

 determination of the position at which a balloon reaches 



