Feb. 23, 1883.] 



• KNOWLEDGE 



123 



If two exactly similar watch-springs, one coiled and the other not, 

 be di8eolTc<l in an acid — the action taking place uniformly, bo that 

 the first spring does not uncoil— will more heat be evolved in the 

 first than in the second case ? If not, what becomes of the energy 

 stored up in coiling ? Stpdk.nt. 



[The times in which the coiled and uncoiled springs are dissolved 

 will not be equal. — R. P.] 



LOGICAL PUZZLE. 



[734] — To those who are familar with Professor Jevons' " Logical 

 Alphabet," it seems perfectly simple to deal with the " Logical 

 Fnzzle " now under discussion in K.nowledgk. 



Thus, when wo combine three terms, X, Y, and Z (not X, not 1', 

 not Z, being denoted by .r, y, and ; respectively), wo have the eight 

 possible combinations : — 



1. .V Y Z 3. X ,1 Z 5. xY Z 7. xyZ 



2. X Y z 4. A' y : e. x Y z 8. w y z ■ 

 unless it can be shown that there is in existence some law which 

 contradicts one or more of these. 



Now, the premises in this case do not contradict any of them, 

 and the burden of proof lies with those who would contradict the 

 conclusion. 



For the Alphabet, see Professor Jevons' "Principles of Science," 

 a treatise on logic of scientific method, second edition, p. 94. 



Freiik. Bi.nyo.v. 



[Hence recognise the value of logic ! Consider that in every 

 possible case of the syllogism the conclusion is obvious : so that, 

 while the trained logician is carefully determining under what form 

 the case would be classified, a clear-minded thinker has formed bis 

 oonclnsion, and gone a long way on with something else. — E. P.] 



SOME ELECTRICAL ANSWERS. 



[Space cannot hereafter be spared for answers to individual 

 querists. — Ed.] 



[735] — J. C. L. II. Both springs should touch. The more iron 

 yon have in your magnets, the higher will be their cjxpacity for 

 magnetisation. Your one object should be to get a strong magnetic 

 field. So long as you attend to this, the shape is immaterial. Why 

 not bend two strips one over the other to form a thick magnet ? — 

 L. B. The sand battery is useless for intensity coils. As you 

 object to the Bnnsen cell, try the double liquid bichromate. — 

 Geo. Allbeury wants to know how lightning protectors are fixed to 

 dhoTch steeples, Ac, without the use of scaffolding. I have seen a 

 modem " Steeple Jack " at similar work. He flew a kite over the 

 Steeple, the thread lodging on the top. This thread was then used 

 to pull a larger one, and so on until a stout rope was passed 

 np the face of the steeple over the top and down the opposite 

 &ce. It was then secured, and the man, hoisting himself up, 

 execnted his work. — J. H. Wakd. 1. Yes, certainly. It would 

 then be a Bunsen cell. Blocks are used in preference to plates, 

 Iwcanse they are cheaper. They are cheaper because they are more 

 easily obtained. It is no disadvantage to have the platinum in 

 the Grove cell thin, as it is not chemically affected. 2. Instead 

 of the secondary layers gradually' i'«creasing in length, they should 

 lather rfecrease. This extra wire is so much resistance inserted 

 without any comijensatiug gain. Maybe your insulation between 

 the primary and secondary is imperfect. Join one end of your 

 secondary to one pole of the battery, and one end of the primary 

 through as sensitive a galvanometer (wound with fine wire) as you 

 can secure. If you get the slightest movement of the needle, your 

 insolation is at fault. You ought with four good Bunsen cells to 

 get a spark of 2 in. or 3 in. 



Teavellebs' Meteoeologicai, Eqcipmext. — The Council of the 

 Meteorological Society announce that they have determined npon 

 holding at the Institution of Ci\-il Engineers, 25, Great George- 

 street, S.W., on the evening of March 21 next, an exhibition of 

 meteorological instruments which have been designed for, or used 

 by, travellers and explorers. The committee will, they state, also 

 be glad to show any new meteorological apparatus invented or first 

 constructed since last March, as well as photographs and drawings 

 possessing meteorological interest. 



Gas v. Electkicitv. — At the half-yearly meeting of the share- 

 holders of the Gas Light and Coke Company (Limited), held last 

 week, the chairman admitted that he was no prophet, and there- 

 fore abstained from making any remark on the future of the 

 electric light. \Vhile assuring his hearers that there was no ground 

 for apprehension, he acknowledged that he does not look to illumi- 

 nating so much as to the cooking purposes of gas to compensate the 

 company for any loss they may sustain from the electric light. 

 [This is somewhat different language from that hitherto adopted at 

 gas companies' meetings. It is nevertheless the most truthful.] 



<!^ur WlAl)iit Column. 



By " Five op Oldbs." 



THE GAME ON PAGE 77, No. GO. 



REFERRING to the remarkable game at page 77, XXXVIII. of 

 Cavendish's selected games, the following passage from that 

 writer's late book will bo found interesting: — 



" Of course, I seldom played at the same table with my father at 

 the Portland," writes Cavendish. " But it occasionally happened 

 that there was only one table, and that we must either play together 

 or lose our amusement. On one of those afternoons 1 was Z in 

 Hand No. XXXVIII., and my father was B. By reference to the 

 game " (Knowledoe, p. 77) "it will bo seen that I played the grand 

 Coup against him. My partner was a very good jilayer. When tho 

 game was over tho following conversation took place : — 



" K. (my partner, to me). — ' You trumped my best diamond.' 



" Ego. — ' I know I did. Wo won the trick by it.' 



" K. — ' I don't SCO how you could win a trick by tramping a 

 winning card.' 



" I should mention that my father had seen the position as well 

 as I had, that he knew I had three trumps (as was clear after my 

 discard at Trick 8), and that he was waiting to be led to in trumps. 

 I noticed, too, from his manner, that he hardly knew whether to 

 feel pleased at my good play, or annoyed at being outmanoeuvred.' 



" Ego (to i'.). — ' Ask " the governor" if we didn't.' 



" Paler (grutUy). — 'Of course you did, of course you did.' 



" I afterwards told Clay of this coup, and he was good enough 

 to say that he admired the discard of the King of Spades at 

 Trick 8. He also chaffed the ' governor ' a bit about my unfilial 

 conduct." 



Note. — Our remark on trick 9, that " it matters not which " trick 

 of the 10th and 11th Z wins, ho wouldllose, is incorrect. If he had 

 let r make the 9th trick, discarding the Club ten, Z could safely 

 have won the tenth trick (trumping his partner's Diamond 8), and 

 placed the lead again in Y's hand by leading a small spade. — Five 

 OF Clubs. 



As you call Cavendish's hand No. 38, set out in your number for 

 February 2 " one of the finest hands ever played," you will perhaps 

 admit some remarks on it adverse to your opinion : — 



Trick 1. — Tlie Score being 4 all, A ought clearly to have led 

 Queen of Clubs. 



Trick 3. — -4, as pointed out by you, ought not to have returned 

 the trump lead. 



Trick 7. — B ought to have led Eight of Clubs, and thus made 

 sure that he or his partner would be fourth player in tho next trick. 

 ^4 playing tho ten of Diamonds cannot have the nine. 



Trick 8. — As B discards Eight of Clubs, he must have three 

 Spades, and Y must hold the Nine of Diamonds. As Z can now 

 make certain of the game if his partner holds the Ace of Spades, 

 and if he has it not must lose it, ho ought, at this trick, to have 

 trumped the Diamond, and tlien have led tho King of Spades, and 

 afterwards a small one. Not trumping, he ouglit to have discarded 

 the Ton of Clubs, and not the King of Spades, for this reason— that 

 (as he does not trump) he cannot win the game unless i' holds tho 

 Ace of Spades, and at trick leads a Diamond. Should Y do this, 

 then if Z retains the King of Spades, ho is certain of winning, but 

 by discarding it he cannot win unless his partner also holds tho 

 Eight of Diamonds or Queen of Spades; this will be at once seen 

 if at trick 11, Y had to lead a losing Diamond or a losing Spade. 

 So that Z played doubly wrongly— I will not say badly. 



Trick 9. llc're again Z played wrongly, as by discarding tho ten of 

 Clubs he could, if his partner had another Diamond (even the 

 losing one) as well as tho Ace of Spades, make certain of winning ; 

 whereas, by trumping, he cannot wn unless his partner holds the 

 best Diamond or the Queen of Spades; so that, in fact, whilst the 

 grand covp was palpably forced on Z, he ought to have played it at 

 trick 8 instead of at trick 9. Not liaving played it at trick 8, he 

 ought to have waited till trick 10. Y also, knowing that the game 

 cannot be won unless Z has three trumps, and also if King and 

 Knave are two of them, unless ho can get rid of the third by 

 trumping, ought to have led the eight of Diamonds as an induce- 

 ment to Z to trump, instead of tho 9th. 



So that it seems to mo that there were altogether seven mistakes 

 in the play ; A making two, B one, Y one, and Z two, and that the 

 play consequently does not deserve the unqualified praise yoa 

 bestow on it. ' Mogul. 



Our esteemed correspondent rather misinterprets our expression 

 of opinion as to the game in question. We referred to the bril- 

 liancy of the finish, not to the play right through. With most of 

 '' Mogul's" criticisms we agree. The discard of Spade King at trick 8, 



