Feb. 24, 1882.] 



• KNOWL-EDGE 



367 



1 iiitod, which, of coarse, cannot be thought of. — C. C. C. The 



;v Tou advance was originally suggested by one Isaac 



■on; but calculation has since shown that the ])henomena 



comets' tails are irreconcilable therewith. We shall 



again to comets by and by, if correspondents will give 



ave. — A. J. Maetin and C. J. C. It would indeed be interesting 



-tronomers if the sun's elevation ^•aried in the way described by 



1 Resident in Glengloy, Upper Lochabor, N.B." But too good a 



li is kept on the sun at Greenwich, Paris, Washington, &c., 



him to play such tricks without our knowing it. // the sun 



Iv shone over a hill this year, at a time of year when formerly 



lid not top the hill, the hill has changed, or the level of the 



und where the house stood from which the obseiTation 



|_ was made. — R. H. Thanks. Solutions neat, but no space. — 



G. S. E. How if he declines to be "relegated ? " — Hr. Ceeagh — C. 



Sorry, but in fairness to other sqaarers must regard all magic 



squares as now done with. — MiCROCRiin. There may be some slight 



difference in the friction, but otherwise can be none. — W. G. Parriss. 



When a gas-flame is blown, the already ignited gas is driven away 



tnm that which in the ordinary course would bo ignited ne.'it ; thus 



(his gas remains unignited, and the other part bums out. The wind or 



breath does not cause combustion to cease ; it prevents combustion. 



Combustion in a steadily-burning flame is beginning and ceasing all 



the time. — W. G. Woolcombe. I cannot reconcile observed facts 



with the jKistulatod law, " a force acting in a direction at right 



angles to direction of motion of a body has no effect in altering the 



direction of motion." That law will be postulated a long while 



before it is established. Write " no effect in altering the velocity 



of motion," and you have less trouble. " That 's how the error has 



arisen." Your geological difficulty suggests that those subjects do 



not greatly attract you ; but with determination it will vanish — Ex- 



PKBTO Cbede. Do not know of any one who sells very extensive series 



of rocks ; but think a letter addressed to Prof. Tennant, of King's 



College, would bring you information on the subject. — J. W. C. 



lioomis's book gives all necessary information for projecting an eclipse 



from the data in Nautical Almanack. Johnson's does not. Believe 



Bogne publisher of latter work. — W. N. W. says second volume of 



Allen's work on "Commercial Organic Analysis" is now issued; 



price, 10s. 6d. — Edm. Hc.vt. We are content to wait. Do not think 



the construction we gave can possibly be misunderstood. — Zares. 



Galileo, no; Xewton did, though. Tou confound inertia and 



momentiun. Every force, however small, affects the inertia, but 



only an equal momentum can match the momenttun of a moving 



mass. I not only "seem to imagine," I know that I am dealing 



with a well-known and well-understood subject. You might with 



advantage study some good text-book of dynamics ; or, for the history 



of the matter, look up Whewell's " History of the Inductive Sciences," 



Vol. II., pp. 45-52. "Thanks for hints how to manage correspondence, 



bnt we see the matter from another point of view. — J. H. M. Such 



mesmeric experiments would do something to establish the claims of 



phrenology, if one were sure the subject knew nothing about the 



bmnps. Your "young man of the name of Walker" (H. ?) may 



have knovm a good deal. — C. T. W. The " equation of time " 



varies slightly from year to year, as the position of the earth's 



perihelion changes. Bnt very slightly. The equation of your 



old dial would, if exact, indicate roughly the time when dial was 



' made. — W.C. My "sub" and I have quite enough to do without the 



classification you suggest. Xow, about your question : I did not 



mean to snub yon, as you say I did ; when you asked how the star- 



p? were to be used in the dark, it seemed an all-sufficient reply 



ly they were not meant to be so used. — W. F. Dexning. I also 



uld have preferred publishing yotir letter. But it could not 



with space at command. — J. Haeborp. I cannot, at this 



nent, recall any earlier references to Mephistopheles in English 



1 ratnre than those in ilsirlowe's " Faustus." 



%ttttv^ lAfCfibrli. 



Bdina, M. K. Fothergill, J. Harloch, G. E. V., Marplot, Per- 

 tinent (read it Pertneus). Cara.s, W. C, G. C. E., J. Harvey, X — Z, 

 Weary, K. Hardy, M. Brant, X. L., Jansen, A. Martins, Halloween, 

 Cardinal Point, J. Easterbrook, L. Murrill, J. S. T.. Curious, 

 J. Tordinham M., X. Eastman, T. Elliott, J. Pearsall, Manchester, 

 IL Pewtress, A Woman, Philalethes. M. B. Q., R. B., Jas. Atherill, 

 F. Brown, J. T. S-m, Post-Prandial (so we should imajrine), C. 

 Carteret. S. Y. Ellis. Porter, A Constant Reader, B. S. S., 

 M. Peewitt, Jas. C. Christie (try Cockle's). 



PoiTD's ErraiCT is a certain t 

 Pond's Eitnw't is a certain cw 

 Pond's Extract is a certain cw 

 Pond's Ertract will heal Bam 

 Pond's Eitract will c 



ire for Bhemnstism and Goat. 

 ( for Hlemorrhoida. 



) for Xeuralgic pains, 

 and Wounds. 

 ) and Bmises. 



Sold by all Chemists. Get the genuine. 



J>pfcial i^oticc. 



Exchange Coli'Mx. — In No. 18 we shall open an Exchange 

 Column, similar to that which has for several years formed a feature 

 in our excellent con*.em|)orary, the English Mechanic. The charge 

 for Exchange notices will be 3d. for the first twenty-four words, and 

 3d. for everj' succeeding eight wortls. 



Sixpenny Sale Column. — We shall also open a Sixpenny Sale 

 Column, in which advertisements will be inserted at the rate of 6d. 

 for the first sixteen words, and 6d. for every succeeding eight words. 



Enlakced Ncmbeks. — We propose, from henceforth, to extend 

 Knowledge to 32 pp. twice, at least, in each month ; and we hope 

 that our growing circulation w^ill enable us to enlarge Knowledge 

 permanently to 32 pp. weekly. If all our readers would help in 

 extending our circulation, which some (whom we hereby warmly 

 thank) have done so effectually, we should very soon adopt a 

 weekly 32 pp. number. 



^otfd on git anti ^cinirr. 



Stove Heat. — Those of your readers who have seen Mr. 

 Williams's article on the " Air of Stove-heated Rooms," and who 

 find stove-heating both comfortable and convenient, may be glad 

 to know that the "Crown Jewel Base Burning" Stove does not 

 diffuse its heat " through red-hot iron ; " it cannot injure, but 

 tends greatly to promote health. I have used one for years. — R. F. 



Inhaling Sulphcretted Uvokogen. — I was surprised to read in 

 Xo. 14, page 203, the remarks of Mr. Mattieu Williams on the 

 inhalation of sulphuretted hydrogen. I was rather careless about 

 the inhalation of this gas until, after suffering six successive and 

 unaccountable attacks of illness, I traced them to this cause. The 

 attacks consisted of violent pains in the stomach, and in each case 

 they occtirred about three days after the inhalation of the gas. 

 I may mention that, finally, in order to make quite sure in the 

 matter, I purposely inhaled a small quantity of the gas, with the 

 result of a slight attack of the pains after the usual interval. It 

 appears to me that it is a gas which produces different effects on 

 various people. In Roscoe and Schorlemmer's new work it is 

 described as " a powerful poison, producing insensibility and 

 asphyxia." This may be true, but it is not the effect it had on me 

 — nor, it appears, on Mr. Williams. — HnS. 



Science Teaching. — At the annual general meeting of the 

 Teachers' Training and Registration Society, and of the Bishops- 

 gate Training College, the other day. Prof. Goldwin Smith took 

 laudable advantage of the opportunity to impress on those present 

 ■what science teaching really means. " In resiMct of the teaching 

 of science," he said, " he had constantly brought before him the 

 wide gulf fixed between the two different kinds of what persons 

 call knowledge. The one was a mere learning to repeat a verbal 

 proposition, and the other was knoT\-ing the subject at first hand — a 

 knowledge based upon a knowledge of the facts. That which they 

 had constantly to contend against in the teaching of science in this 

 country was that teachers had no conception of that distinction, for 

 they thought it quite sufficient to be able to repeat a number of 

 scientific propositions and to get their pupils to repeat them as 

 accurately as they themselves did. If he might offer one suggestion 

 to the governing body of the college, it was that so far as they 

 taught science at all they should aim at giving real and practical 

 scientific instruction ; that it should be confined to those things 

 about which there was no dispute ; and that the teacher should be 

 instructed that his business in teaching was to convey clear and 

 vivid impressions of the body of facts upon which the conclusions 

 drawn from those facts were based." 



Biting. — A Serpent, if surprised suddenly, or brought to bay at 

 close quarters, may be too terror-stricken to attempt flight ; then 

 it bites, following a curious general rule which seems to obtain 

 throughout nearly the whole animal world, from a passionate child 

 downward, no matter what the natural weapons of offence may be. 

 Young Felidce will keep their talons sheathed until they have 

 exerted all possible force with their soft milk-teeth, and a lizard 

 will seize the hand which restrains it with its insignificant little 

 jaws, when its tail or claws might inflict far more injury. The 

 Boidee never use their constrictive powers in self-defence (unless 

 they are gripped), and it seems probable that if a venomous snake's 

 fangs lay in its tail, it would use its teeth Jirst when attacked before 

 bringing them into play. Indeed, it must be remembered that very 

 few animals are provided with exclusively defensive weapons, and 

 that the python's enormous strength in constriction, the viper's 

 poison apparatus, the lion's teeth and claws, and the electric dis- 

 charge of the gymnotus are given them primarily for the purpose 

 of securing their food. — Arthur Stradling, in Nature. 



