FOR GENERAL READERS. 



FRIDAY, JULY 13th, 188S. 



CONTENTS. 



Scientific Table Talk 25 



The Voltaic Balance ... 26 



The Blackman Air Propeller {illus.) ... 27 



Auditory Organ of the Gnat 28 



Dye Colours from Plants and Shrubs ... 28 

 Extraordinary Escape from Lightning 



{illus.) ... ... ... ... 29 



The Naturalist at the Seaside : 



I. The Tow Net ... 30 



General Notes ... ... ... ... 31 



Buds (illus.) 33 



Natural History : 



Orchids, What are they ? {illus.)... 35 



Bifurcated Palm Tree 36 



Natural Food for Young Trout 

 Miscellaneous Notes 



Canon Wren 



Reviews : 



Notes on Inorganic Evolution 

 Journal of the Franklin Institute... 



Abstracts of Papers, Lectures, etc. : 

 Geological Society of London 

 Manchester Cryptogamic Society 

 Edinburgh and Glasgow Geologi- 

 cal Societies 

 Geological Class, Edinburgh Uni- 

 versity 

 Bewickshire Naturalists' Club 



PAGE 



PAGE 



• # 



The Social Condition of the Babylonians 



42 



• 36 



Poisons and Poisoning ... 



44 



■ 37 



Correspondence : 





• 3S 



• 38 



The Rings of Saturn — Effect of the 





Venom of the Rattlesnake on 





Itself 



46 



• 39 



Answers to Correspondents ... 



46 



41 



Recent Inventions 



46 





Technical Education Notes 



47 



• 41 



Announcements ... 



47 





Sales and Exchanges 



48 



. 42 



Selected Books ... 



48 



42 



Meteorological Returns 



48 



SCIENTIFIC TABLE TALK. 



By W. Mattieu Williams, F.R.A.S., F.C.S. 



In my last I referred to a discussion with a friend whose 

 views I greatly respect. We were perfectly agreed 

 respecting the truth and universality of the great induc- 

 tion usually described as " the conservation of energy," 

 though I may add, by the way, that I heartily agree with 

 Mr. Herbert Spencer's objection to the form of expression 

 that is generally accepted. He objects to it on the same 

 ground as that of his objection to the term, " preservation 

 of the fittest," for which he has successfully substituted 

 " survival of the fittest." " Conservation of force," or 

 " conservation of energy," as he says, implies " that 

 energy would disappear unless it were taken care of, 

 and this is an implication totally at variance with the 

 doctrine enunciated" (Nature, vol. v., page 263). I do 

 not remember whether he has proposed an alternative 

 term. 



Indestructibility of energy and indestructibility of 

 force appear to me far better terms. They are more 

 correct and more expressive, besides corresponding with 

 the earlier-accepted description of what is virtually the 

 same, viz., the " indestructibility of matter." 



The difference, between myself and friend, referred to 

 the fate of the hailstone supposed to enter our atmo- 

 sphere with planetary velocity, and having its planetary 

 velocity arrested by atmospheric resistance. According 

 to his view of the doctrine of the conservation of energy 

 the mass of ice — whatever be its size — must be heated 

 throughout, seeing that the motion of the whole mass is 

 arrested throughout. My view is that the whole of the 

 heat into which the mechanical motion is converted is 

 primarily evolved at the place where the arresting force 

 is applied. 



It is evident from Sir W. Thomson's slashing criticism 

 of Schwedoft's theory, that my friend's view is shared 

 by others, and I have reason to believe that I am not 

 alone. 



To illustrate the difference between these views let us 

 take an imaginary case. Suppose that two bodies of 

 equal mass, both solid, perfectly rigid, inelastic, and incom- 

 pressible, and both non-conductors of heat, are moving 



withequal velocitiesin exactly opposite directions, and then 

 come in collision. The visible motion of both will be 

 arrested, and then what will happen ? According to the 

 first view each body will be instantly heated throughout. 

 According to my view, they will be heated only at the 

 colliding surfaces. 



We cannot actually make this experiment, because we 

 can find no substances having the perfect rigidity, etc., 

 demanded, therefore the reader may fairly ask why I 

 make such demands in my ideal case. This will appear 

 as I proceed. 



According to my view, the arrest of motion is only 

 apparent. I regard the conservation or indestructibility 

 of motion as the fundamental fact, and the conservation 

 or indestructibility of what we call energy as merely 

 the outcome or sensible expression of this. In all 

 practical cases of collision the mass-motion is converted 

 into several motions, a part of it directly into heat 

 motion, another part into mechanical vibration, another 

 possibly into- electrical or chemical motion, etc., as the 

 case may be. 



As an example of such communication of motion in 

 other form than that of heat, I may mention that when 

 in Sheffield I was consulted concerning damage alleged 

 to be done by certain steam-hammers in shaking the 

 foundations of surrounding houses, and devised a simple 

 instrument — a sort of seismometer — which proved that 

 a hill about 200 feet high, half a mile long, the summit 

 of which was about one-third of a mile distant from the 

 hammers, was bodily shaken by the concluding strokes 

 of the hammer upon blooms of puddled iron. When 

 the steam-hammers were very busy the crockery ware 

 placed on shelves in the houses around was endangered, 

 as the general vibration caused it to travel gradually to 

 the edge of the shelves and then topple over. 



In this case a considerable proportion of the arrested 

 mechanical motion of the hammer was merely transferred 

 as mechanical motion to the body of the earth, and thence 

 to the houses, etc. 



A further examination of the doings of such steam- 

 hammers is instructive. When the glowing, spongy ball 

 of iron receives its first few blows, it crushes down, and 

 at each compression its temperature is visibly increased. 



