yan. 14/1875] 



NATURE 



^65 



or processions, or trumpets, or inaugurations, was to them 

 quite incomprehensible, and hence their misrepresenta- 

 tion of his work and character, when they tell us that he 

 looked upon mankind merely as objects of experiment, 

 and not with any philanthropic feeling, and that " il ne 

 s'agissait que de nourrir les ouvriers assez bien pour 

 entretenir cher eux la force musculaire des membres." 

 Those portions of his essays in which he describes the 

 work done at the " House of Industi'y '' in Munich utterly 

 refute these mistaken views of Rumford's character. 



I have read nothing more humiliating in reference to 

 the still remaining magnitude of popular ignorance of the 

 merest i"udiments of physical science than some of these 

 essays. Take as an example this passage on page 177 of 

 vol. ii. " The waste of fuel in culinary processes, which 

 arises from making fluids boil unnecessarily, or when 

 nothing more would be necessary than to keep them 

 boiling Iwt, is enormous. I have no doubt but that 

 nruch more (han half the fuel used in all our kitchens, 

 public and private, in the whole world, is wasted precisely 

 in this manner." Again, he tells all the world that 

 '• nothing is so ill-judged as most of those attempts that 

 are so frequently made by ignorant projectors to force the 

 satne Jirc to perforin different services at the same tijne. 

 The heat generated in the combustion of fuel is a given 

 quantity, and the more directly it is applied to the object 

 on which it is employed so much the better, for less of it 

 will escape or be lost on the way ; and what is taken 

 away on one side for a particular purpose can produce no 

 effect whatever on the other side where it is not." 



These, and quite a multitude of similarly simple and 

 obvious applications of the elementary laws of heat, were 

 not only expounded but practically applied by Runifoid 

 eighty or ninety years ago, and we are still blunder- 

 ing on and blindly violating them. Every laundry is 

 still filled with the steam of wastefuUy boiling coppers, 

 and almost every saucepan in the United Kingdom and 

 elsewhere is wastcfully used for the unnecessary distillation 

 of water, not one cook in 500 knowing that water is no 

 hotterwhenit boils violentlythan when it "simmers"gently. 

 Nine-tenths of the ranges exhibited at the last Exhibition 

 of South Kensington were constructed in direct violation of 

 the simple and obvious principles above stated, and our 

 ironmongers still persist in making "kitcheners," "ranges,'' 

 &c., with the fire in the middle, the oven on one side, and 

 a boiler on the other, or even with ovens on both sides ; 

 instead of placing the fire on one side, the oven next, and 

 boiler beyond, to utilise residual heat. In most of our 

 best English houses a range capable of cooking for a 

 dinner party of thirty or forty people is kept going to 

 supply water for a tumbler of toddy, although Rumford 

 demonstrated again and again the vast economy and con- 

 venience of having several fires in every establishment 

 where the demands for cooking are variable, and his 

 essays give descriptions and drawings of how these fires 

 should be arranged. 



It must be remembered that Rumford was no mere 

 theoretical wtiter or lecturer, but he practically carried 

 out on large and small scale every principle he expounds. 

 He cooked for thousands and tens of thousands in his 

 military kitchens, his House of Industry, in private houses, 

 at the Foundling Hospital in London, at public institu- 

 tions in Dublin, Edinburgh, &c. ; and in these practical 



demonstrations weighed his fuel, registered its consump- 

 tion, and published the results. 



Thus, at the Foundling Hospital he roasted 1 12 lbs. of 

 beef with 22 lbs. of coal, the residual heat from the 

 roaster going on to the boiler. In the public kitchen at 

 Munich, where his arrangements were fully carried out, 

 he frequently— as certified by the Colonel and Councillor 

 of War— prepared the ordinary hot dinner for one thou- 

 sand persons, and " the expense for fuel has not amounted 

 to quite twelve kreutzers" (less than 4^^;'., or one-fiftieth 

 of a farthing for each person). It must be remembered, 

 in reference to this, that Rumford's soup requires five 

 hours' boiling, or rather heating at the boiling-point. 



I have little doubt that the merited failure of all the 

 recent competitors for the Society of Arts' prize was due 

 to the absence of scientific knowledge, and of that syste- 

 matic inductive method of proceeding by the aid of which 

 Rumford wedded theory to practice, and brought forth 

 such important results. His researches on the " Propa- 

 gation of Heat in Fluids," upon which our present know- 

 ledge of the phenomena of the convection of heat is mainly 

 founded, were suggested by burning his mouth with a 

 spoonful of thick rice soup, and were further elaborated 

 in order to determine the best material for soldiers' 

 clothing. His celebrated demonstration of the immate- 

 riality of heat was in like manner a result of cannon- 

 boring. Every essay in these three volumes supply 

 similar illustrations of the action and reaction of theory 

 and practice upon each other, and their mutual develop- 

 ment thereby. 



One of the most curious and least-known of his specu- 

 lative efforts is that upon " the mechanical principle of 

 animal life." They bear upon many of the molecular 

 speculations now occupying so much attention, and are 

 sufficiently interesting to demand full quotation of the 

 following essential paragraphs : — 



" Suppose an open vessel — as a common glass tumbler, 

 for instance — containing a piece of money, a small pebble, 

 or any other small solid opaque body, to be filled with water 

 and exposed in a window, or elsewhere, to the action of 

 the sun's rays. As a ray of light cannot fail to generate 

 heat when and where it is stopped or absorbed, the rays, 

 which, entering the water and passing through it, impinge 

 against the small solid opaque body at the bottom of the 

 vessel, and are there absorbed, must necessarily generate 

 a certain quantity of heat, a part of which will penetrate 

 into the interior parts of the solid, and a part of it will 

 be communicated to those colder particles of the water 

 which repose on its surface. 



" Let us suppose the quantity of heat so communicated 

 to one of the mtegrant particles of the water to be so 

 small that its eftect in diminishing the specific gravity 

 of the particle is but just sufficient to cause it to move 

 upwards in the mass of the liquid with the very smallest 

 degree of velocity that would be perceptible to our organs 

 of sight were the particle in motion large enough to be 

 visible. This would be at the rate of about one hundredth 

 part of an incit in a second. 



" This velocity, though it appears to be slow in the ex- 

 treme when we compare it with those motions that we 

 perceive among various bodies by which we are sur- 

 rounded, yet we shall be surprised when we find what 

 a rapid succession of events it is capable of producing. 



"If we suppose the diameter of the integrant particles 

 or molecules of water to be one-millionth part oj an inch 

 (and it is highly probable that they are even less), m that 

 case it is most certain that an individual particle, moving 



