khb. 3, n 



KNOWLEDGE ♦ 



305 



pnblUiiere ; and yonr lator letter, being also addressed wrongly, 

 is opened probably a week after the paper reached you. — 

 11. KoLFE. i)o not know Richardson's Conic sections. For analy- 

 lical conies, Todhnnter or Salmon; for geometrical. Drew or 

 Tayler would snii, I thi»k. You require a book suitable for fourth 

 ■tage, at Kensington. Perhaps some correspondent will help. — 

 Anontmods, Silverdalk. Darwin's works are published by Murray. 

 I-yell's " Student's Geology" and "Principles of Geology " would 

 be good works to begin with ; say, tiret, the cheap edition of the 

 former work published by Murray. — M. S. S. Already corrected ; 

 but thanks all the same. — A. Blvmenb.xch, G. .Iohnsox, H. Stei.v- 

 li.\N, and others. Nos. 2 and 3 are now out of print. They cannot 

 be reprinted ; this has already been done three times, at a serious 

 loss.— Feed. Cr.4Mpton-. Toll us about the monkey, by all means. — 

 K. Mlirhead Little. Wo did not understand F.C.S.'to mean that 

 carbonic oxide is non-poisonous, or a supporter of combustion. 

 Kveryone with the most elementary knowledge of chemistry is 

 aware that it is more poisonous than carbonic acid or 

 the carbonic dioxide, and that it is no more a sup- 

 porter of combustion than the latter. What we understood 

 him to mean was that wood gas, after the carbonic acid in it 

 had been converted into carbonic oxide, was changed in character, 

 aa described. Coal gas contains both CO and CO;. Head as 

 you understand it, "F. C. S.'s" communication would describe wood 

 gas as simply carbonic oxide, which i.«, of course, simply absurd. — 

 Satellite. The card of your compass must be badly suspended. 

 Hold the compass horizontally, and if the card evidently "sticks," 

 lap the sides till the card vibrates freely, it will then swing rotmd 

 till the north end points to the magnetic meridian (abont 21° west 

 of true north. A " Knowledge Almanac " may be thought of hei-e- 

 after : atjpresent. KNOttXEDGE occupies all our care. — A. J. Maas. 

 Thanks for snake stories.— T. J. Sun extinguishing fire dealt 

 with in article on 'Fallacies." The common idea that sun 

 puts out fire is rery different from the theory yon deal 

 with, that a fire bums less quickly in a room whose air has 

 been warmed by the sun (after a certain considerable time). 

 Sunlight admitted into a room does not warm the air in the room 

 ap|>reciably for some time ; the fire is supposed to go out quite 

 ([uickly, which certainly does not happen. — H. B. K. About tobacco 

 immediately. — Cl. A. Segler and F. Gaubeet. Wo knew Zares 

 uiade the mistake yon mention. Our answer was quite correct. 

 There is no need of the isolation you suggest to produce conditions 

 under which the least possible force will move the greatest possible 

 mass. But at what rate ? Zares said nothing about that. We 

 know perfectly well where and how he is astray; but it is more 

 useful to let kim find his way to the right road, than simply put 

 liim on it and leave him plantc lo. — J. Broadhckst. American 

 humour is as distinct from English humour as possible, 

 as are American ideas abont humour from ours ; or, I should 

 rathor say, from ordinary English ideas on the subject. The 

 actor approved by English tastes is often not liked in America; and 

 I'ifc-fcrsii, favourite American actors arc often regarded with little 

 favour here. Again, if yon go with American friends to a play in 

 England, you v.ill find that what the English audience like they do 

 not care for ; while they at once select as the best actors those who 

 are not regarded as absolutely in the first flight by most English 

 critics. I must confess it seems to mo they often show a more 

 refined taste than ours, — perhaps because 1 find their views in agree- 

 ment with my own. For instance, I have always regarded 

 Rutland Barrington as one of the very best of our histrionic 

 humorists, but his quiet humour seems very little appreciated com- 

 pared with the more grotesque fun of other actors on the same 

 boards. Now I find Americans quite at one with me in this view. 

 The oftenerthey see him the better they like him. It seems to me, by 

 way that so consummate a judge as M. Got, of the Comedie 

 Franijaise, was of the same opiuion, even when he saw Barrington 

 in a part so comparatively ungrateful as that of Captain Corcoran. 

 Americans say that ninety -nine Englishmen out of a hundred fail to 

 understand American hnmour at all. I remember an English 

 fellow-passenger on board an American Pacific steamer, to whom 

 the most ontrageous absurdities were addressed with a certain grave 

 calm (not solemnity), which should have been as suggestive of fun 

 •8 Harrington's manner in telling us of Teazing Tom j but he took 

 them in as confidently as he received the announcement of the 

 day's run and the ship's latitude and longitude, and for aught I 

 know, entered them in a big book about his travels which he was 

 writing. He was "a perfect gold-mine of fun," a Califomian said. — 

 Mcsicrs. You may be right. Conversation when music is going on 

 may set the performer .at his ease. He might be still more at his ease 

 ■ f the audience stopped their ears with cotton wool, and still more 

 so if they all went out of the room. But the object in view when 

 any one is invited to play, is not to set him or her at ease, but to 

 hear sweet sounds discoursed. If a player is so inferior as not to be 

 at ease, common sense suggests that he should not be invited o 



play. If, on the other hand, he plays well, yon may depend ho 

 will not be set at case, but very much the reverse, if ho is 

 not paid the compliment of silence. But to say the truth, no 

 one who knows what music is either talks when others play, or 

 does what you seem so to desire to do, talks when playing 

 himself. I have heard many musicians speak of the habit 

 some unmusical persons have of talking when music is in pro- 

 gress, and they have — one and all — denounced the practice as 

 an offence to the audience and an insult to the performer. — P. P. A. 

 Your assertion that a strong artificial light will put out a fire would 

 entirely dispose of C. T. B.'s explanation, which yet yon say is the 

 only one yon can arrive at. It is very easy to make a few experi- 

 ments either on the effect of sunlight, or of strong artificial light. 

 First get a good, steadily, blazing fire, with the shutters of a 

 south-facing room closed, on a sunny day. Open the shutters for a 

 quarter-of-an-honr, and note how during all that time the fire ap- 

 pears dull and languid. Close the shutter.^, and note that as soon 

 as the eyes have become accustomed to the change, tho fire appears 

 as bright as ever. As you say, it does not appear so at once ; but 

 that is simply becamse the effect of sunlight on the eyes does not 

 pass off at once. I do not mj-self agree with F.R.A.S. in 

 regarding the idea that sunlight puts out a fire as a mere 

 vulgar superstition, but rather as a very natural illusion. 

 Moreover, there can be no doubt that solar heat, admitted 

 long enough into a room to appreciably increase the tempe- 

 rature of the air. does, to some degree, diminish the activity 

 with which a fire burns. This is no more a superstition than the 

 perfectly correct idea that fires bum brightly in frosty weather. 

 But you mu.st remember that F.R.A.S.'s remark was altogether 

 impersonal ; it was not applied to the belief of the querist, for none 

 was indicated: it expressed only F.R.A.S.'s view respecting tho idea 

 about which N. inquired. — J. F. The earth's axis is inclined 

 23° 27' 1G60" from a perpendicular to the plain of her orbit. Tho 

 equality of action and reaction does not — exactly — mean " that if a 

 man in a boat pushes against another boat ten times tho weight of 

 his own, the heavier boat would go one tenth of the distance 

 of the lighter one " ; though something like this would follow 

 from the law : it means, more generally, that whatever pressure, 

 strain, or action is exerted by one body on another, excites an 

 exactly equal pressure, strain, or action in this other body, acting 

 in the opposite direction.— M. J. IIabding. I have taken tho 

 liberty of forwarding your suggestion to the publishers of my 

 " Ea.sy Star Lessons." But surely it would be rather hard if an 

 author were regarded as responsible for the pictures put on the 

 binding of his book. As to the other work, considering who 

 honoured the author in the way you mention, and the absurd 

 remark he made, I should attach no weight at all to his opinion, 

 liowon earth could tho writing of a scientific treatise be regarded 

 as equivalent to a course of education specially fitting a man for 

 ministerial duties ? It was the hard hitting, I should imagine (and 

 infer from the title of the book), which pleased tho bishop. Tho works 

 attacked seem to me perfect models of what scientific works should 

 be, presenting accumulated knowledge, attacking none, courteous to 

 all, even to opponents. A book attacking such works, and having for 

 its title what implies that those attacked arc godless and wicked men, 

 caiTies its own condemnation on its title-page. That it should have 

 run to the twelfth edition would show that there are many who 

 enjoy such attacks, but would prove nothing as to the scientific 

 value of the treatise. — E. Lee. We cannot find space for all the 

 titles of Mr. Dallinger's es.'ays. We fear the original query should 

 not have been inserted. We might till onr whole number with re- 

 plies, if many such questions were asked. — A. Lummer-son. Have 

 inserted one of your queries ; as to the other, tho person named is 

 considered a dreamer in his own country, and has no scientific 

 standing either there or here.— W. G. S. Certainly yon heard 

 the SOU puffs in nine seconds less time than was required to 

 produce them. In the case of an approaching train, you 

 always hear the sounds in quicker succession, and in a re- 

 ceding train, in slower succession, than if tho train were 

 at rest, or if you were a passenger by it. — S. H. W. Nay: if 

 a cannon-ball w"erc sent round tho earth without any initial rota- 

 tional motion, it would in each circuit present all parts of its 

 surface towards the earth — not constantly the same face. Tho 

 other passage seems carelessly written. If a mass of air came from 

 the pole, in a moment, to our latitudes, nothing could boar tho 

 brunt of passing through it. But north-east winds come only from 

 higher latitudes gradually to our own, and the deficiency of their 

 original rot.itional motion is gradually made up by the frictionni 



action of tho surrounding air, earth's surface, Ac. T. S. V. P. 



Read Wallace's book on modem miracles if you want tho sort of 

 faith you refer to. We cannot admit the subject here until 

 it has, or some part of it has, a scientific standing.— Jas. 

 Devlin. Yes ; we quite mean that the builders of the Great 

 Pyramid could not possibly have oriented it so perfectly 



