March 10, 1882.] 



KNOWLEDGE « 



405 



proximity to the sun, and some density of the sun's atmosphere, it 

 mnst have sufifered some resistaBce and retardation ; and therefore, 

 being attracted something nearer to the sun in eveiy revolution, will 

 at last fall down upon the body of the sun." 



Another fact with respect to Sir Isaac Newton's correct judg- 

 ment as to the internal heat of the son is worthy of being mentioned, 

 especially as a contrarj' theory with regard to a cool dark body 

 within the photosphere survived down to the tirao of Sir John 

 Herschel. In a letter dated IGth April, 1681, Sir Isaac Newton 

 says, '' Now though the inward part of the sun wore an earthy 

 gross substance, yet, if the liquid shining substance, which Mr. 

 Flamstced supposes to swim upon it, be then hot, it will heat the 

 matter within as certainly as melted lead would heat an iron bullet 

 immersed in it. Nor is it material whether the liquid matter on 

 the suR be of any considerable thickness. An iron bullet would 

 heat as fast in a quart as in an ocean of melted lead, this difference 

 only excepted, that the bullet would cool a small quantity of lead 

 more than a great one. If, then, the liquid matter swimming on 

 the sun be but so thick as not to be cooled by the central parts (as 

 it must be), it will certainly heat the central parts, for it imparts 

 heat to the contiguous matter as fast as if it were thicker, and 

 keeps all ceol environing mediums (the instrument of cooling 

 things) from coming near the central parts to cool them. By which 

 means the central parts must become so hot, as if the hot fluid 

 matter surrounding it equalled the whole vortex. The whole body 

 of the sun, therefore, must be red hot," &c. 



A. C. R.\NY.\RD. 



INTELLIGENCE IN CATS. 



CORRESPONDENTS of Knowledge, in treating of cats, do not 

 seem to have remarked some acts of intelligence which may 

 be observed daily in the streets of London. At the cry of the cat's- 

 meat man all the cats are in commotion, but all are not excited by 

 the cry of the same man. A dozen men may walk up and down a 

 street with the tempting morsels, calling "meat, meat I " but only 

 at those houses which they are accustomed to servo will the cats 

 be ronsed by the call. No sooner does the proper man arrive in a 

 street than every cat he is accustomed to serve rushes frantically 

 to the door, or, if allowed, into the street, running mewing towards 

 him, rubbing against his legs, or sometimes sitting in a begging 

 attitude before him, but never, as far as I have observed, attempting 

 to steal from the open basket. 



One day I noticed a cat whose man had either forgotten her 

 portion or had been unable to make her mistress hear, and so had 

 passed on. The cat, however, insisted upon being attended to ; she 

 ran after him, mewing piteously, and when at last she made him 

 understand, she ran back to the house before him, where by that 

 time the mistress was ready to take the delicacy so much prized by 

 all London cats, however well fed. I have often watched this act 

 of discrimination in our own cat. Tom would sit quietly dozing 

 whilst man after man went by with the famDiar cry of " Meat, 

 meat," but presently he would jump up, rush to the window, and 

 remain in a state of great excitement, and soon after a distant cry 

 of " Meat " might be heard, and we knew that Tom had recognised 

 his own man long before we had heard him. As the cry drew 

 Bearer, Tom's excitement increased, and he would almost fly to the 

 door. A singular fact remains to be told. On Saturdays the man woidd 

 leave two portions, as he did not go his rounds on Sundays. These 

 were often th^o^vn into the area, to which Tom had access. He 

 would always greedily devour the one portion, but never touch the 

 other, although they lay side by side. This cat would also open the 

 latch of the kitchen-door, as observed by several of your corre- 

 spondents, :\nd would also open the shutters in the drawing-room 

 (closed but not fastened), in order to look out of mndow. I have, 

 however, been told of a cat who would open not only a latch, but 

 an ordinary drawing-room doer, rather loose, by taking the round 

 knob between her paws and twisting it round and round till it 

 opened. 



The fact of cats distinguishing between one meat man and 

 another seems tc me to disprove the oft-repeated assertion that cats 

 attach themselves only to places, and not to persons j tor here we 

 see them able to pick out a certain man by his voice alone, even at 

 a great distance. A. W. Buckland. 



WOOD-GAS. 



IF I may be permitt'.d to do so, I should like to say a few words 

 in reply to Lewis AjTindel's '' elucidation" of my ab.«tract on 

 "Wood-gas," not " Carbon Monoxide," as he construes my meaning. 

 If, on line 12 of the abstract, page 216, the word can between the 

 words "we obtain" had been inserted, Lewis Arundel might have 



been saved the trouble of elucidating my description (or — more 

 strictly speaking — my informing the readers of Knowledge that 

 there was such a thing) of " Wood-gas." I am sorry I did not make 

 my meaning clearer. 



The "dangerous, obnoxious, and otherwise objectionable pro- 

 ducts" referred to are N : S : U^S : CS„ and tar. N in the form 

 of ammonia, which is ^artually absent. Little sulphur can exist in 

 any form, while there is but a trace of sulphuretted hydi-ogen or of 

 carbon bisulphide, and there is not a trace of tar. 



I did not previously enumerate these for fear of taking up, 

 needlessly, too much space in your paper. 



Lewis Arundel evidently mistakes the acid taste (or, perhaps, 

 the tingling in the nose, when inhaled through that organ), of COj 

 for an odour ; that is to say, if ho is dealing with C02inaj)«r8 

 state when he perceives the odour about which he is so certain. 

 Ho might as well say that hydrogen had an odour, because he 

 himself had never obtained it odourless. I cannot think he could 

 be in earnest when he said (re CO;), " whatoverour text-books may 

 copy from one another." Is it likely that the leading chemists of 

 the day, in writing theii- text-books, simply " copy from one 

 another" without beiBg themselves thoroughly conversant with the 

 peculiar properties of the subject under their notice ? 



What would Lewis Arundel say to the man who told him that 

 the snow they were looking at was green, because ho (the man) 

 was unaware that he was looking at the snow through green glasses ? 

 This is not a bit more ridiculous than to say that chemists " copy 

 from one another," re the odour of COo. 



The blue flame of CO is hardly observable over a sluggish fire ; 

 on the contrary, it is seen on the top of a " glowing " fire, mth a 

 background of red-hot bricks. Lewis Arundel would see how the 

 CO is formed by referring to my text-book. 



He now asks, " How, then, can it confer on ' an inferior coal-gas ' 

 a ' great candle-power ' ? " This, I own, is not quite clear, my 

 mistake being that, in trying to be concise, I was too concise — 

 when I say that the coal and wood-gas are mixed with naphtha 

 vapour, Lewis Arundel wiU see how "the great candle-power" is 

 conferred. I may say, before concluding, that '" after the first 

 charge of wood has been carbonised, the charcoal, instead of being 

 dra^vn, as with coke, is pushed back into the retort," &c., <ic. This 

 is repeated with the second charge, and so on. 



Anyone who has to make the gas, carbonic oxide, will see the 

 caution given in all text-books, i.e., its very poisonous property. 



F. C. S. 



FOR NEXT WEEK. 



"VTEXT week, an interesting paper by Dr. Ball, on the Future of 

 -LN the Earth and Moon, will appear, and one by Dr. Carpenter, 

 on Dr. Siemens' recent communication to the Koyal Society, 

 respecting a possible use of the seemingly waste energies of the 

 sun. In response to a number of queries respecting the motions of 

 planets with respect to the earth, and the explanation of the advance, 

 retrogradation, and stationary points of the planets, I have deter- 

 mined the distance and bearing of the planet Mars from the earth 

 at intervals of ten days from the opposition of 1875 to that of 

 1892, and, having set them down in a chart, have carried through 

 them the various convolutions representing the path of Mars dtiring 

 those seventeen years. The result (which is rather curious, and 

 represents much more labour than many would perhaps suppose) 

 will be presented next week in a two-page chart. 



RiCHAKD A. PrOCTOE. 



METEOROLOGICAL REPORTS. 



I PROPOSE from and after the vernal equinox, at latest, to 

 publish weekly reports of the weather, based on the daily 

 records obligingly supplied from the Meteorological Oflicc. As yet, 

 the plan on which these reports will bo given has not boon decided 

 upon, nor can we at present assign the space we can afford to give to 

 the subject. 



OMISSIONS AND CORRECTIONS. 



WE omitted to notice in the foot-note relating to the book by 

 Dr. De Lays, on the Brain, that it forms one of the Inter- 

 national Scientific Series, published by Messrs. Kegan Paul & Co., 

 and that its price is os. The treatise on the Sun, by Professor 

 Young, has been included (since our review appeared) in Messrs. 

 Kegan Paul & Co.'s announcements as belonging to the same series, 

 at the same price. For the Nineteenth Centurij, in the " Answers 

 to Correspondents" for last week, p. 393, Ist col., line 17, read the 

 Century (which, we believe, was what was originally written). 



