19G 



♦ KNOWLEDGE ♦ 



[Marcu 30, 1883. 



tions of Dr. Ciould, when they come to hand, agree as well, 

 it will be proof positive that no sensible resistance or dis- 

 turbance of any kind was surt'i-rod by the comet in passing 

 witliin 300,000 miles of the sun's surface at the rate of 

 .'100 miles a second. 



Of course, if the view we have taken is correct, there 

 is no possibility that our comet can return in six months 

 and fall into the sun. Not that there is any alisurdilrj in 

 the idea by itself considered. Tf the comet of 1880, when 

 receding from the sun, had uio\ ed in an orbit corresponding 

 to a three years' period, and if the present comet were 

 found to have a period of three years or less as it is now 

 recedin" from the sun, it would be almost impossible to 

 refuse to admit their identity, and probable speedy absorp- 

 tion in the sun. 



We close with a single word as to the probable con- 

 sequences of a comet's fall upon the sun. Unquestionably, 

 the energy of the comet's motion would be transformed 

 into heat, and if the comet had any considerable mass, say 

 -, ,V„ the mass of the earth, the heat produced would be 

 enough to supply the sun's hea^expenditure for months. 

 Probably, however, no comet has a mass anything like so 

 great as that ; more likely the present comet even, huge as 

 it is, has a mass less than -Y^^l-un of the earth's, so that its 

 collision with the sun would produce as much heat only as 

 the sun would expend in eight hours. 



Now, if the sun were a cool, solid, or even liquid mass, 

 the sudden accession of merely this quantity of heat would 

 undoubtedly produce an enormous rise of temperature and 

 a great increase of radiation. I'>ut, constituted as the sun 

 is — mainly a mass of gas and vapour — the effect would be 

 entirely different, the energy being principally expended in 

 producing expansion and evaporation, with comparatively 

 little increase of temperature or radiation. If one stirs 

 up the fire under an open kettle, the water gets no hotter 

 — it only boils faster. Probably the eftect of the fall of a 

 body, even as large as the earth, iipon the sun, would be 

 hardly anything more than to restore the sun to the condi- 

 tion it was in a century ago. The energy lost in the course 

 of a century would be replaced — that is about all. During 

 the few moments while the body was passing through the 

 sun's atmosphere, there might be, and probably would be, 

 phenomena of great interest and beauty to those who were 

 on the watch ; but it is very doubtful whether people 

 generally would know anything about the occurrence until 

 they read of it in the papers. 



THE CRYSTAL PALACE ELECTRIC 

 AND GAS EXHIBITION. 



rpHERE is not much in the way of progress to record 

 J_ in the electrical section. The north nave is tolerably 

 well filled with various exhibits, while preparations are 

 rapidly approaching completion for what promises to be 

 a gorgeous display by the Gulcher Company of Gulcher 

 arc and Crookes incandescent lamps. We hope to be able 

 to give a detailed account of this exhibit when it is 

 finished. The Duplex Company's exhibit has been with- 

 drawn, owing, it is said, to pressure of business elsewhere. 

 One of the most satisfactory features of the exhibition is 

 the illumination of the space in front of the theatre by 

 half-a-dozen Fyfe-JIain arc lamps. Their light is remark- 

 able for its steadiness and brilliance, and fully confirms the 

 impression created on the occasion of their first exhibition 

 at the otHce of the Daily J'<'l''i/ra]>/i. 



Turning our attention to the more extensive Gas Exhi- 

 bition, the incandescent and regenerative gas lamps remain 



the striking features of interest. According to the cata^ 

 logue, there should have been four systems of incandescent 

 gas-lighting exhibited, but only three of them are to be 

 seen. First amongst them we may mention the Lewis 

 burner, which is illustrated in the accompanying sectional 

 diagram. Gas at the ordinary pressure is supplied to the 

 P 



outer pipe or tube, A A. Air under a pre.ssure of 1 2 in. 

 of water, after passing through the inner tube, B, mingles 

 at D with the gas in A. The mi.xture then passes through 

 the series of tubes, E S F, to the combustion chamber, P, 

 which consists of a small cap of fine platinum wire gauze. 

 The volume of air passing through B is three times the 

 volume of the gas consumed, and the force of the current 

 passing upwards "induces' another volume of air through 

 the two tubes C C. The gas is first turned on gently, and 

 then lighted, and the quantity increased until the flame is 

 no longer seen, when the platinum commences to incandesce 

 or glow. The quantity is gradually increased until the cap 

 become brilliantly and uniformly luminous. This, then, is 

 the principle of the flameless incandescent gas-light, and 

 one great advantage pertaining to it is that the proportion 

 of consumed to unconsumed is very considerably increased ; 

 while again, it may be utilised for the consumption of gas 

 inferior to that usually supplied for lighting purposes. 

 S S is a short tube of steatite, which, being a non-conductor 

 of heat, prevents the heating of the lower parts of the 

 burner. It is claimed that the light is equal to five 

 candle-power per foot per hour, so that as the ordinary 

 sized Lewis burner, with a platinum cap half-an-inch in 

 diameter and an inch or so long, consumes eight feet of gas 

 per hour, its luminosity is equal to forty candles. An 

 ordinary gas jet consumes about five feet, giving a light of 

 sixteen candle-power. It is also worthy of consideration 

 that the "carbon in the gas is so perfectly consumed that a 

 polished silver reflector, placed immediately over the burner, 

 is not tarnished in the slightest degree." 



The cost of the compressed air is naturally an important 

 consideration, more, perhaps, on account of the extra piping 



