58 



KNOWLEDGE, 



[Maboh 2, 1891. 



hot-water pipes. The liquid is some sohition having a 

 very low freezing-point, such as a solution of calcium 

 chloride in water, hriiw being the term generally applied 

 to such solutions. 



In the ammonia machines a special cylinder for expan- 

 sion is not required, the expansion being allowed to take 

 place in long coils of tubing, which are placed in a bath 

 in which the brine is kept circulating. From this bath 

 the cold brine is driven by pumps through the system of 

 tubes. An important advantage possessed by the ammonia 

 machines is the fact that there is no moisture to be re- 

 moved, and their construction is in consequence con- 

 siderably simplified. Except on board ship they have 

 undoubtedly an advantage over the air machines, and are 

 coming daily into more general use. For marine ijistalla- 

 tinns — to use the trade term — the air machines are still 

 preferred, owing principally to the fact that in case of 

 accident the working substance could not be removed in 

 the case of ammonia, the escape of which, owing to an 

 accident in rough weather, would, moreover, be highly 

 inconvenient. 



An interesting application of cooling by means of brine 

 has lately been made in mines. One of the greatest 

 difficulties which can occur in the operation of sinking a 

 shaft is that presented by a stratum of sand saturated 

 with water. In more than one case this difficulty has 

 been overcome by freezing the sand and water into a firm 

 mass and then continuing the sinking operations as if the 

 material were solid rock. The shaft ha\dng been simk to 

 the upper surface of the quicksand, a number of small 

 bore-holes are made to the bottom of the stratum, and in 

 these are placed tubes closed at the bottom, through 

 which cold brine is circulated from a tank at the surface, 

 which is cooled by an ammonia machine. In the course 

 of a few days the quicksand is frozen to a solid mass, and 

 the boring can be proceeded with. It will thus be seen 

 that the production of artificial cold is an industry which, 

 though still in its infancy, has already attained considerable 

 importance. It appears likely that the next ten years 

 may see a development scarcely less rapid than that of the 

 last decade. 



Bv W. Montagu Gattie, B.A.Oxon. 



T 



HE following is an elementary explanation of the 

 play of the hand published in the February 

 number of Knowxedge. For convenience of 

 reference, the distribution of the cards is here 

 repeated. 



D.— Kg., 5, 3, 2. 



C— 0, 8. 2, 



H.— 10, 7, 4, 2. 



S.— 10, H. 



D.— 8, 7, i. 



C— Ace, G, 5, 8. 

 H.— Kn., '.), C, 5. 



S.— 6, 2. 



Z turns up 



g the King of j^ 



Diamonds. 



I).— Ace, Qn., 9. 

 C.-Qu., Kn.,7,4. 

 H.— Kg., 8, 3. 

 S.— Kg., Qn., 5. 



1).— Ku., 10, 6, 

 C— Kg., 10. 

 H. — Ace, Qn. 

 S.— Ace, Kn., 9, 7, 4, 3. 

 Trick 1. — A opens his longest suit, and, having four 

 only, leads the lowest ; Y, holding king and another. 



passes the trick ; V> plays his highest card, and Z his 

 lowest. 



Trirk 2. — B, by opening with a small heart, shows his 

 partner four at least of that suit. He might return a 

 club ; but this would not be quite prudent, and would 

 also be likely to mislead A, inasmuch as the immediate 

 return of a partner's suit is usually interpreted as a re- 

 quest for a third round on which to make a small trump. 

 Z plays his lowest heart, and A his highest ; and Y of 

 course wins the trick with his ace. 



Trick 3. — Guided by considerations which have been 

 explained already, Y leads a trump, and, having three only, 

 opens with the highest, so as to assist his partner {who 

 has turned up the king) as much as possible. Z gathers 

 that Y has not more than three trumps ; for he would 

 not lead knave from a long suit unless he held the four 

 honours, or king, queen, knave, and two others, and both 

 these cases are precluded by Z's holding the king. Z 

 therefore finesses the knave, and at the same time takes 

 occasion to commence an " echo " to the trump lead by 

 playing the three instead of the deuce. When the deuce 

 falls at trick 5, four trumps at least are marked in Z's 

 hand. 



Trick 4. — A continues with the queen of clubs in order 

 to clear the suit. He knows that (unless the ten of clubs 

 was the beginning of a call for trumps ) Y has either the 

 king single or no more ; but in the latter case Y would 

 pass a small card led (for, B having played ace on the 

 first round, the king must then be with Z), and Z might 

 win with a small card, retaining the command of the suit. 

 B's three of clubs shows that A led from four cards ori- 

 ginally ; for, the deuce having fallen already, the four 

 must have been A's lowest club, and, with five of the suit, 

 he would have led the lowest but one. Z plays his lowest 

 card, and, as this is the eight, it follows that the only 

 other club he can hold is the nine (the knave, of course, 

 being marked in A's hand). 



Trick 5. — Y continues with his next best trump, Z 

 completes his " echo," and the ten draws the ace from A. 



Trick 6. — A is reluctant to enable Y to make a small 

 trump on the clubs, and therefore returns the hearts. 

 Holding two only, he returns the higher, and, as B and 

 Z play sis and four respectively, Y concludes that the 

 three is in A's hand. He notices also that B, who led the 

 five at trick 2, now plays the six, and therefore can only 

 have had four hearts originally ; so that, as A can have 

 but one (the three), Z must hold the other two. 



Trick 7. — After this third round of trumps, Y counts 

 the hands, from inferences already drawn, thus : — Z's 

 " echo " at tricks 3 and 5 has shown that he has the long 

 trump ; he has two hearts, from trick 6 ; and not more 

 than one club, fi-om trick 4. Therefore he must have at 

 least two spades. A has the knave of clubs and one other 

 (tricks 1 and 4), and the three of hearts ; therefore he 

 must have three spades. There remain for B two hearts, 

 and either two clubs and two spades, or three clubs 

 and one spade, according as Z has the nine of clubs or 

 not. 



Trick 8.- — Z's proper lead is obvious enough. It would 

 be fatal to lead up to Y's tenacc in hearts, and he cannot 

 do better than give his partner the best spade he has. A, 

 holding king, queen, naturally puts on the queen to draw 

 the ace and make his king good ; but, looking at the great 

 strength in spades declared in Y's hand, it would probably 

 be better play to pass the ten, and that course would cer- 

 tainly save the game, whether Y jiiiesscd or not. A's play, 

 however, is quite orthodox. Y's couji has already been 

 fully explained. Its merit consists in his seeing that, ex- 

 cept in the improbable case of Z's holding the best and 



