Aug. 11, 1882.] 



♦ KNOWLEDGE 



179 



In the case first considered, with the cumulus clouds two 

 miles high, it can be readily shown (we do not trouble our 

 readers ^\-ith the proof) that the angle at which the clouJ 



surface (which seems to meet the horizon almost vertically 

 at A and B) is really inclined to the observer's horizon 

 plane, is an angle of only about If degrees. In the latter 

 case, this angle is only about 54 minutes, or nine-tenths of 

 a degree. 



If we take the quadrant BAD in Fig. .5, divide it into 

 three parts in E and F, and FB again into three parts in e 

 and/] then the tenth part of B/is a degree, and BAc/ 

 represents the larger of the angles just mentioned. Thus, 



Fig. 5. 



when cumulus clouds hang about two miles high in clear 

 air, the cloud-bank near the horizon. Fig. 5, instead of being 

 nearly vertical (or like AD), as it seems to be, is inclined 

 like A(/ to AB. When the clouds are half-amile high, the 

 inclination is only half of even this small angle. 



Since, then, the cloud surface to which we pay most 

 attention, that near the horizon, is seen thus aslant, 

 instead of squarely, or nearly so, as we seem to see it, we 



can understand how much room there is for illusion as to 

 the true forms both of separate clouds and of cloud masses. 

 Such illusions we shall next proceed to consider. 



(To he continued.) 



LEARNING TO SWIM. 



By Xatatob, 



EVERY ONE admits that we ought all to be able to 

 swim ; yet, if you ask the first ten men you meet 

 whether they can swim, you will find that at least five 

 cannot, and of women (who can learn to swim much more 

 easily than men) not one in ten can swim. Yet, out of a 

 hundred men in all classes above the very poorest, ninety- 

 nine have the chance of teaching themselves to s\\-im with 

 perfect safety, and quite easily, for one part at least of 

 every year ; and nearly the same proportion among women 

 have similar opportunities. 



It seems to me the reason why, despite the talk which 

 goes on every year in the summer and autumn months 

 about learning to swim, so few who might do really achieve 

 the easy task, is that erroneous ideas are formed respecting 

 the thing to be learned. A skilful swimmer, professional 

 or otherwise, describes the art of swimming as eventually 

 it should be acquired by the learner. He tells a man or 

 boy who cannot support himself for a moment in the- 

 water — except, perhaps, by lloating on his back — that he 

 must go through such and such movements. Here is a 

 learner's first instruction, extracted lerhatim from an old 

 magazine : — " Suppose a person standing up to his breast 

 in water, and about to strike off in swimming : the hands 

 are placed close to each other, with the palms undermost 

 near the breast, the body is thrown forward in the waler, 

 the hands are thrust out, and when the arms ar.' fully 

 e.xtended, they diverge horizontally (the la:ks of the hands 

 being turned towards each other), describing curves" 

 [excellent description], " until they are brought round 

 under the armpits and again extended. WhUst the arms 

 are describing their curves, the legs are drawn forwards 

 \mder the body, the knees being separated as much as 

 possible, and the toes turned outwards, and whilst the 

 arms are regaining their extended position, the legs are 

 extended backwards and outwards, the soles of the feet 

 being turned outwards." Now this is very pleasant to 

 read. So the learner, standing up to his breast, puts his 

 hands close together, the palms undermost near the breast, 

 throws his body forward in the water, and presently comes 

 up spluttering, having accomplished no part of the sug 

 gested operations except " describing curves " very vaguely 

 and very uncomfortably. 



The fact really is, that the first efibrts of the learner 

 should be of a much less ambitious kind. No one ever yet 

 learned to swim all at once ; and many are prevented from 

 learning to swim at all by the circumstance that f icry oiu 

 fuiU who tries to do what most books on swimming tell 

 him to do, and what professors of swimming pretend to 

 expect him to do. 



In the first place, the learner should not stand breast- 

 high in the water, at least on a sloping shore, or where 

 there is any stream. Not many years ago, some simple 

 lessons on swimming, begiiming with some such advice as 

 we lm\ quoted above, led a l>cginnor to his grave ; for. 

 tumbling forwards in trying to carry out the instructions, 

 he liegan to flounder, and floundering into deeper water, 

 was drowned. In a batliing-place with level floor, a learner 

 may safely take his first lessons with the water up to his 



