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KNOWLEDGE. 



[September 1, 1899. 



Physical research leads us to believe that heat cannot be 

 destroyed but only transformed ; yet many persons seem 

 to think that this heat vanishes like a ghost without trans- 

 formation and without producing any effect. This may 

 be so, but it is so much opposed to physical analogies that 

 we should be slow to accept it unless on the basis of 

 definite observations which, I think, it will be admitted 

 are not at present forthcoming. Nor can we confine the 

 question to the suu. The loss of radiant heat must (on 

 the theory which I am now considering) extend to all the 

 stars. A larger portion of the heat of some of them is no 

 doubt intercepted by other bodies, but some of it must 

 escape — vanish. The whole universe is losing heat ; or 

 at least it is losing motion, for the supply of heat may be 

 temporarily kept up by the conversion of motion into heat 

 (aa, for example, by a bombardment of meteorites). But 

 that a good part of the radiant heat vanishes, thus lessening 

 the total amount of force — of heat and its equivalents — in 

 the universe, seems to be a common opinion. This theory, 

 however (for of course everything on the subject is theory), 

 will strike many of your readers as unsatisfactory for 

 physical, not metaphysical or theological, reasons. But if 

 this heat be not lost, what becomes of it ? 



If the sun's rays and those of the stars always met with 

 some material body, however great its distance might be, 

 the problem would be solved ; there would be no loss of 

 heat to the universe. The sun may at present be radiating 

 more than it receives, and, consequently, cooling ; but in 

 travelling through space it may reach other regions in 

 which these conditions will be reversed. But it seems 

 plain that if this be the case, the greater part of the bodies 

 which encounter the solar heat are dark bodies, or else 

 that there is an absorption of light in passing through the 

 ether. Such an absorption of light and heat by the ether 

 — as maintained, I believe, by the great observer Struve — 

 would equally solve the problem ; for the light and heat 

 thus absorbed could not be lost, and would probably be 

 given back by the ether to material bodies in some manner 

 not yet traced. Otherwise, it would change the properties 

 of the ether. 



A third possible alternative is that radiation, like gravi- 

 tation, only acts between material bodies, and that, though, 

 like gravitation, it acts on a material body in any direction 

 and follows it in all its movements, there is no expenditure 

 of force in the directions in which no material body is 

 encountered. On this theory also there would be no loss of 

 heat. There would only be an interchange of the same kind 

 as if every heat-ray ultimately encountered a material body. 



Knowledge since its foundation by Mr. Proctor has 

 always distinguished itself by its readiness to discuss 

 questions of this kind. Mr. Proctor was indeed more of a 

 theorist than an observer, and his spirit has not died with 

 him ; and I trust that the pages of Knowledge will con- 

 tinue to be open to the theorist as well as to the observer. 



,., W. H. S. MoNCK. 



DARK RIFTS AND LANES IN NEBUL,E. 

 To the Editors of Knowu;dge. 

 SiKs, — The dark rifts and lanes which are visible in Dr. 

 Robert's splendid photograph of the Nebula N.G.C. 

 2237-9 Monocerotis are most remarkable, and, as Colonel 

 Markwick points out in your issue for this month, it is 

 very difficult to explain their cause. The idea that they 

 are holes right through the nebula, so that we are able to 

 see through them the dark space beyond, is open to very 

 serious difficulties. A possible explanation which occurs 

 to me, and which I don't think has yet been suggested, is 

 that the darkness is caused by patches of cool gas being 

 on the outside of the nebula and between us and the 



incandescent gas beyond. This layer of cool gas would be 

 quite opaque to the light coming from the bright portions 

 of the nebula, and would thus cause a dark patch. The 

 spectrum of the nebula is of such a simple kind, con- 

 sisting of only a few bright lines, that the light coming 

 from a star situated beyond the nebula would shine 

 through one of these dark patches, and the only change 

 in its light would be caused by a few dark lines in its 

 spectrum, which would lie in the same position aa the 

 bright ones in the spectra of the nebula. If these dark 

 patches are caused, aa I suggest, in this way, it is, I think, 

 possible that they may be more clearly seen in the photo- 

 graphs of nebuliB than when they are examined visually, 

 as the ultra violet end of the spectrum would be more 

 affected by the absorption of the cool layer. 



We know yet so very little about the nebul.T, and have 

 so few solid bases to build upon, that I merely offer this as 

 one possible explanation of these curious dark rifts. 



"W. E. 'Wilson. 



'We regret to record the death of Prof. Robert Wilhelm 

 Eberard Bunsen, which took place at Heidelberg on 

 the 16th August. As most students of science know, 

 Bunsen for more than half a century past exerted a 

 profound influence as a preceptor on a large proportion of 

 leading chemists of the day. Born at Gottingen in 1811, 

 after studying in the university of his native place, he 

 amplified his attainments at Paris, Berlin, and Vienna, and 

 then became professor of chemistry in Cassel, Marburg, 

 Breslau and Heidelberg in succession. At the latter place 

 he built a grand laboratory, and made it one of the best 

 schools of its kind in Europe. Among his discoveries are 

 the burner which bears his name, the electric pile, mode 

 of producing magnesium on a large scale, and, in con- 

 junction with Kirchoff, spectrum analysis, which in the 

 hands of chemists has added so much to our knowledge of 

 the elements, and under the control of astro-physicists has 

 given birth to the new astronomy — a branch of practical 

 science opening up new vistas in celestial space and 

 evolving a simple, yet wonderful, means of deciphering 

 the hieroglyphics of the stars. Many lives have been 

 saved by his discovery of hydrated oxide of iron aa an 

 antidote to arsenic poisoning. Perhaps the most striking 

 of his contributions to science is that of 1861, when he 

 proved the presence of rubidium and cffisium in a few 

 drops of mineral water from Durkheim by the aid of the 

 spectroscope, and his evaporation of several tons of the 

 water to obtain a sufficient quantity of the new metals to 

 experiment with. Among his chief works are : " On a 

 New Volumetric Method," " A Treatise on Gas Analysis," 

 and " Chemical Analysis by the Spectroscope." 



Sir Edward Frankland, a famous pupil of Bunsen, died 

 in Norway on the 10th August. Born at Churchtown 

 in 1825, he was educated at Lancaster Grammar School, 

 and afterwards studied chemistry under Dr. Lyon Playfair 

 in the Museum of Practical Geology, working away at 

 chemistry for a twelvemonth in a laboratory fitted up in 

 the cellar kitchen of a house in Duke Street, Westminster. 

 He then went, in company with Tyndall, to the labora- 

 tories of Liebig and Bunsen at G lessen and Marburg. 

 Frankland was appointed Professor of Chemistry in Owen's 

 College in 1851 ; St. Bartholomew's Hospital in 1857 ; 

 the Royal Institution in 1863, and the Royal College of 

 Chemistry (now the Royal College of Science), in 1865. 

 He is author of ' ' Researches on the Isolation of the 

 Radicals of Organic Compounds," receiving for the same 

 a gold medal from the Royal Society in 1857 ; also " On 



