306 



KNOWLEDGE 



[Feb. 3, 1882. 



iiK they ilid withont trlfucnpic nid, uiiIcbk tliey hiul employed 

 sucli mctlKMlB nB we lincl tlioy artnnlly did employ. The work wa« 

 much more diflU'ult tliiin yon seem to think. — llfriii. Every 

 rctlci'tiiiK Irltwdpe (uxcopt those of ihe hirgo Iternchelinn type) 

 hnH two roth'ctorM, which arc nut meant to bo used BOparutely. 

 Telling nie thnt the eye-glajiHia are hoth eolniirod red, one lighter, 

 the olher (ii« I might nlmont linve inferred) darker, docs not enable 

 me to underxtnnd wlmt in wrong. Vou Bliould get an optician to 

 look nt the inittrument. — Onwakh. Your lirat question out of our 

 line.— W. A. Saiilkr. We think not ; but if you will deRcribe any 

 cxperimentB showing (loif sun rays might build up a planet, we 

 shall exiiminc them with exteeding interest.— Rkpokter. No room 

 for shorthand discuBsions. — Ernest (iKorii. Much obliged. Ilavo 

 already, however, inserted a reply similar in effect to your own very 

 complete one. — (i. U. Mortimer. What can you mean ■- What i» 

 the substance of a light ? In a gas-flame, the light is due to 

 plowing carbon, tlio heat coming from tho combustion of 

 hydrogen.— W. E. B. F. C. S. Hid not meet Mr. Severn in Aus- 

 tralia; but ho was woll-remembcred there, as wore his lectures on 

 astronomy. Do not know his address. Probably Mr. Ellcry (Mel- 

 bourne) may know. — E. li. V. I considered most of tho phenomena 

 you refer to in an article which apjie-ired (iftecn years ago or so in tho 

 Intellectual Ohserier. I may deal with it shortly in these pages, 

 but so many subjects crowd in upon Knowlbdge, that it is hsird to 

 know which to take first. The apparent changes in brightness are 

 only subjective, not objective, phenomena — they depend on the 

 different brightness of different parts of the background. The 

 shadow of IV. ought to bo larger (including penumbra) than that of 

 III., IV. being so much further from the planet. — J. A. L. R. How 

 would your explanation apply to the moon? The enlargement 

 certainly is an optical illusion, as measurement shows. The climate 

 question will be raised in articles on I'recession. Sun's proper 

 motion wants an article for its ;.roper elucidation. In my 

 " Essays on Astronomy " it is discussed rather fully. The velocity 

 has not yet been measured, and cannot be. Otto Struvo's reasoning 

 was quite unsound. As to tho Vectors question, there is an obvious 

 misprint. Is it not rather unfair to ask questions of that kind, 

 leaving us either to occupy a portion of space for the query and 

 replies, besides giving trouble to readers and to us in reading their 

 answers, or else to send us to look up tho book, which may or may 

 not be ready to our hand ? If all our readers who encountered 

 such difficulties sent us queries, our whole space and more would be 

 wanted for them.— T. W. Yes ; the guillotine cutter works easily 

 enough when fed ; it is tho feeding takes the time. Tlie extra expense, 

 when we are doing our best to give as much extra matter as we can 

 provide for out of our scanty margin (or, rather, looking forward 

 for the margin we hope to have when full gro^vn) counts, of coarse, 

 tor nothing. The "nice little job" you have "cut out for our 

 readers as well as ourselves too " we beg respectfully to decline. In 

 an article such a matter may be discussed, not in replies to queries. 

 — H. Skell. Thanks. Another letter pointing oat the same mistake 

 is in type. — ^^ioLUs .ind Borea.s. It was your own joko about storms 

 being sent us out of a gun. Did you think we " took you " seriously ? 

 Your questions too wide for the kind of answers you want. — J. A., 

 L. M. B., A Caktdusia.v, and others. Thanks for various solutions of 

 the four fours problem, or approximations thereto. — GriNOis. Tes, 

 the errors are there, but one is an obvious misprint, and neither 

 affects the result. — F. B. Y'ou are right ; that " was what we in- 

 tended to convey, officially."— W. B. Corrected already.— P. A. 

 MAtilAnoN, T. R., and others. The problem is not difficult with the 

 Dif. and Int. Cal. " No analyst " wanted a solution he could 

 follow. Thanks, however, for your solution. — J. Hammabd. Much 

 obliged for your solution of the messenger problem. We had 

 already sent a geometrical solution to the printer's. At present we 

 have scarcely room for mathematical essays ; two have been waiting 

 for room since the fourth number. We agree with yon about leaving 

 mathematical "problems " for a week, but not mathematical ques- 

 tions, simply because querists may be anxious for early reply. The 

 simultaneous equations later. — E. J. Kex.nedv. Y'our solution will 

 not do; the " by symmetrv' " as.sumption is unsound. Note, that 

 you get, besides the solution, an equation of condition. Why should 

 this ecpiation hold ? 



The Fi-TiRE of Solar Physics.— The fundamental problems 

 now pressing for solution are, " first, a satisfactory explanation of 

 the peculiar law of rotation on the sun's surface ; second, an ex- 

 planation of the jieriodicity of the spots, and their distribution ; 

 third, a determination of the variations in the amount of the solar 

 radiation at different times and different points upon its surface ; 

 and fourth, a satisfactory explanation of the relations of the gases 

 and other matters above the photosphere to the sun itself— the 

 problem of the corona and the prominences." — The Xation. 



^otfS on ^vt ant) ^rirnrf. 



Thk Eablikbt Date or a London Foo. — What the earliest record 

 of n I/ondon fog may be I am unable to Btat« ; but since Mr. Hales 

 ha* mentioned Evelyn'n name in connection with a fog noticed by 

 him in 1C81, it will undoubtedly hove struck more than one of your 

 readers thot twenty-three years previous to this, the delightful old 

 iliarist had published his " Fumifuginm, or the InconTeniencie of 

 the Aer and Smoak of Ijondon dissipated, together with some 

 Remedies humbly proposed by J. E., Esq.," Ac. " Published by 

 His Majcstic'B command," m.hc.lxi. The warmth of expresirion 

 used in this little tractate, now vprj' scarce, would certainly 

 point to the long-settled existence of the fog and smoke 

 nuisance in the metropolis; indeed, the energy of tho attack of 

 this original Fellow of the Royal Society, his notice of the injury 

 done to the health of the inhabitants, to the public buildings of 

 London, and the furniture and "movables" generally, singularly 

 coincide with the sentiments expressed about us in the present day. 

 In the midst of our boasted civilisation and advance, the words of 

 this accomplished gentleman of the seventeenth century are as 

 mncl) to the point on the question of the London fog and smoke 

 nuisance as they were 221 years ago. Evelyn mentions ("Diary" 

 Dec. 15, 1670) " the thickest and darkest fogg on the Thames that 

 wos ever known in the memory of man." — T. Caeew Maktin. — 

 Athenaum. 



CnLOEOFOEMlxo DCRIKG SLEEP. — The possibility of chloroforming 

 a person in sleep, without waking him, having been disputed in a 

 recent murder trial. Dr. J. V. Quimby, of Jersey City, was led to 

 test the question experimentally. The results were presented in a 

 paper before the section of Medical Jurisprudence at tho meeting of 

 the Medical American Association, a few days ago. Dr. Quimby 

 made arrangements with a gentleman to enter his room when he 

 was asleep and apply chloroform to him. This he did vnih 

 entire success, transferring the person from natural to artificial 

 sleep withont arousing him. He used about three di-achms of 

 Squibb's chloroform, and occupied about seven minutes in the 

 operation. The second case was a boy of thirteen, who had 

 refused to take ether for a minor operation. Dr. Quimby 

 advised the mother to give the boy a light supper and put him to 

 bed. She did so, and Dr. Qnimby calling when the boy was asleep, 

 administered the chloroform and performed the operation withont 

 awakening the boy. The third case was a hoy of ten years suffering 

 from an abscess, and the same course was pursued with ecjual 

 success. Two important inferences may be drawn from these cases. 

 Dr. Quimby said : — minor surgical operations may be done with 

 perfect safety and much more pleasantly than in the ordinary way ; 

 and, secondly, a person somewhat skilled in the use of chloroform 

 may enter a sleeping apartment and administer chloroform with 

 evil intentions while a person is asleep. Hence the use of this drug 

 in the hands of a criminal may become an effective instmment in 

 tho accomplishment of his nefarious designs. — Medical Advance. 



Cri'.siaceaxs and Light. — In a recent p.iper communicated to 

 the Paris Academy M. de Merejkowsky describes experiments in 

 which he sought an answer to the question, " Do the lower cmsta- 

 ceans distinguish colours ? " His answer is that it is exclusively 

 the quantity, not the quality, of light that affects them. Larvae of 

 Balanus, a cirrhipede crustacean, were employed, and some of the 

 experiments were repeated on certain marine Copepoda. In a 

 vessel that is quite dark these crustaceans are dispersed in all 

 directions, but if daylight be admitted through a slit they collect 

 about the entering beam. This occurs, too, when light of only one 

 colour is admitted (a coloured liquid being put liefore the slit). 

 These crustaceans do not seem to be blind for any colour (a result 

 corresponding to what M. Bert observed in the case of Daphnides). 

 But to find out whether they perceive colours as well, the 

 following experiments were made : — Two slits being used for 

 a beam of white and of coloured light respectively, the crusta- 

 ceans preferred the former beam, all clustering round it if 

 the coloured light was deep real or violet, and a large majority if 

 that was of a brighter tint (yellow, green, or bright red). Com- 

 paring a beam of darker colour, aa violet, with one more luminons, 

 as yellow, the crustaceans always preferred the latter. With two 

 slits admitting coloured ruys of eqnal brightness, the crustaceans 

 divided into two equal parts, whatever the colouration (the anthor 

 thus compared bright red with yellow, green, and blue, yellow with 

 green and blue, and green with blue) : but directly the brightness 

 was rendered unequal the groups of crustaceans became unequal, 

 too. M. de Merejkowsky concludes, then, that in perception of 

 light there is a great difference between the lower crustaceans and 

 man, and even between them and ants; "while we see different 

 colours and their different intensities, the lower crustaceans see only 

 a single colour in its different variations of intensity. We pcrceiTO 

 colours as colours ; they only perceive them as b'ght." — Tiiiios. 



