March io, 1892] 



NATURE 



439 



Regnault, Frost, Fairbairn, Tate, and others have shown that 

 the rate of expansion of superheated steam is almost identical 

 with that of air and other permanent gas, if calculated not too 

 close to the temperature of maximum saturation. In passing 

 steam through pipes heated by the hot gases from the furnace, 

 the effect is not much, if any, better than using a trap to sepa- 

 rate the water of condensation. 



It is obvious that, for steam to pass from a boiler into a super- 

 heater, the latter can only be at the same pressure as the boiler, 

 or somewhat lower, and the gasification in transit is not 

 attended by increased density nor exalted tension ; hence the 

 failure of ordinary superheaters. 



Practical engineers — makers of high-pressure engines for the 

 trade — discovered long since that compression of steam at the 

 end of each stroke, or steam cushioning, notwithstanding certain 

 theoretical disadvantages, yielded an average efficiency greatly 

 in excess of free discharge of steam from the cylinder. In this 

 case superheating, of course, occurs, by compression, under cir- 

 cumstances insuring exalted tension ; hence the economy. 

 Hook's law, " Ut tensio sic vis," cannot be translated into ♦' Ut 

 calor sic vis." John Gamgee. 



The Laboratory, 3 Church Street, Westminster, S.W., 

 February 23. 



Poincare's "Thermodynamics." 

 I FEAR M. Poincare has not read my review of his book with 



sufficient attention. Otherwise he could hardly have written the 



letter printed in your last number. 



The chief objections I made, taken in the r^'^r^t; order of their 



importance, were 



1. The work is far too much a mere display of mathematical 

 skill. It soars above such trifles as historical details, while 

 overlooking in great measure the experimental bases of the 

 theory; and it leaves absolutely unnoticed some of the most im- 

 portant branches of the subject. 



[Thus, for instance, Sadi Carnot gets far less than his due, 

 Rankine is not alluded to, and neither Thermodynamic Motivity 

 nor the Dissipation of Energy is even mentioned ! ] 



2. It gives an altogether imperfect notion of the true founda- 

 tion for the reckoning of absolute temperature. 



3. It completely ignores the real {i.e. the statistical) basis of 

 the Second Law of Thermodynamics. 



If these are what M. Poincare alludes to as " reproches 

 generaux, centre lesquels ma preface proteste sutfisamment," I 

 can only express genuine amazement that a Preface should be 

 capable of having such powers, and envy the man who is able to 

 write one. 



As to smaller matters : — I did not attack M. Poincare's printer, 

 I virtually said he was excusable under the circumstances. And 

 as to the quite subsidiary question which M. Poincare seems to 

 think I regard as the most important, I have only to say that I 

 could scarcely be expected to know that the words " on n'a pu 

 jusqu'ici constater V existence des forces electromotrices, &c.," 

 imply, as M. Poincare now virtually interprets them, " One has 

 not yet been able to assign the origin of the electromotive 

 forces, &c." P. G. T. 



4/3/92. 



The Function of a University, 

 Yet one more definition — it is no part of the business of .\ 

 University to teach, says Prof. Fitzgerald in Nature of Febru- 

 ary 25 (p. 392). We have now the following definitions of the 

 function of a University : — 



1. It should be a mere examining body, e.g. the London 

 University. 



2. It is a place for the cultivation of athletics, good breeding, 

 and gentlemanly behaviour. 



3. At the University there should be taught classics, mathe- 

 matics, and pure science. 



4. TheProfessorsof the University should teach MJ,f/M/ subjects 

 like mechanical and electrical engineering, medicine, &c., as at 

 Cambridge. 



5. The true function of the University is the teaching of 

 useless learning. 



6. Ii is no part of the business of a University to teach. 

 Truly, a wide choice of definitions, and seeing that the 



teaching of applied science which has been developed "at 

 schools, technical coUetfes, by patent-mongers and the trade," 

 NO. II 67, VOL. 45J 



aided " by a lot of savages," has been recently appropriated by 

 the Universities, I have no doubt, when these degraded mortals 

 have similarly worked out a system of teaching applied literature, 

 that a seventh definition of the function of a University will be 

 added later on, viz. : — 



7. At the University, modern languages and literature are 

 studied in such a way as to be of the greatest value to the nation 

 at large. 



As Prof. Fitzgerald relegates the teaching of things useful to 

 the class of pariahs mentioned above, perhaps he will tell us 

 whether he raises the study of mechanical and electrical 

 engineering to the lofty position of uselessness, or whether he 

 utterly condemns the appeal that is now being widely made — 

 made even to technical teachers — for aid in the establishment of 

 engineering laboratories at a University which has recently 

 thought that the best place to obtain an assistant was a London 

 technical college. 



He thinks that students, "if they are so ill prepared that they 

 have not acquired the art of learning, should go to a College, ..." 

 and not to the University. I presume, then, that they ought to go, 

 for example, to the Colleges of Trinity or St. John's, but not to 

 Cambridge ; or to the Colleges of Balliol or Christ's, but on 

 no account to Oxford. Perhaps this somewhat conflicting 

 advice is the result of Prof. Fitzgerald's studying literature " for 

 its own sake," as contrasted with studying language for the 

 sense it conveys. Examples were recently given in a leader in 

 one of the daily papers illustrating that the public utterances of 

 some of the most prominent advocates of the compulsory 

 teaching of Greek conclusively proved that it was not to 

 improve their English that they had studied the classics. 



In the same lucid way Prof. Fitzgerald adds : " The Bible 

 produced very little effect until it was read in translations ; and 

 the danger of a pagan revival, if ancient literature were studied 

 without the obstruction of difficult languages, is the best reason 

 for insisting on those languages in a Christian University." 

 Surely a man of his wide intellectual power cannot mean that 

 the general reading of the Bible, which became possible after it 

 was translated into modern languages, is to be deplored. But 

 neither, on the other hand, can he mean that the incalculable 

 benefit, that has resulted from the translation of the Bible into 

 the vulgar tongue is an argument for the suppression of free 

 translation. On whichever horn of his own dilemma he decides 

 to pose himself, I, at any rate, have no sympathy with the 

 Roman Catholic dogma that good comes from making the 

 knowledge of the truth difficult of attainment by the world 

 at large. 



He chides me with forgetting the debt electrical science owes 

 to those who studied it while useless. Does the statement that 

 one Volt sends one Ampere — that is, one Coulomb per second — 

 through one Ohm look as if the practical electrical engineer had 

 forgotten the labours of Volta, of Ampere, of Coulomb, and of 

 Ohm ? Indeed, is not Prof. Fitzgerald himself forgetting the 

 deep debt of gratitude the theoretical study of electricity owes 

 to its practical applications ? The late Prof. Fleeming Jenkin, 

 a Professor at a University bear in mind, wrote in 1873 :— " In 

 England at the present time it may almost be said that there are 

 two sciences of electricity — one that is taught in ordinary text- 

 books, and the other a sort of floating science known more or 

 less perfectly to practical electricians. ... A student might 

 have mastered Delarive's large and valuable treatise, and yet 

 feel as if in an unknown country and listening to an unknown 

 tongue in the company of practical men. It is also not a little 

 curious that the science known to the practical men was, so to 

 speak, far more scientific than the science of the text-books." 



While there are University Professors like Thomson, Hertz, 

 and Fitzgerald, what matters it whether we call them the 

 teachers or ourselves the learners ? When the work they are 

 now carrying on may be of incalculable service to the practical 

 man in the future, of what avail is it to discuss whether it is to- 

 day useful or ttseless ? For the labours of such men I have too 

 profound a respect and admiration to "sneer" at what I hold to 

 be the true function of the University. 



But equally worthy of respect do I think is the teacher in a 

 school of engineering — that is, one who aims at presenting use- 

 ful knowledge, and the methods for extending it, in such a form 

 as to be most easily grasped by those who intend to devote their 

 lives to engineering. 



My friend Prof. Fitzgerald and I are at any rate wholly in 

 accord on one important point urged in my recent inaugural 

 address, viz. that it is the special function of the technical school 

 to teach ttseful knowledge. W. E. Ayrton. 



