Jan. 2 0, 188 I J 



NA TORE 



269 



rests on an incline. Of course the footstocks of the 

 skates being too low behind would produce the same 

 effect as too low a heel to the boot, i.e. throw the balance 

 too far back. .-•— ■ 



Fig. 3 shows the position the skate will have on the ice 

 if the heel is too high, i.e. the centre of pressure is thrown 

 too far forward, and consequently the skate must roll up 

 behind in order to get the proper balance. 



In Fig. 3 is shown a skate in the proper position on the 

 ice, i.e. with the heel raised so high as to throw the centre 

 of pressure on the centre of the foot and skate. 



The proper height of the heel of the boot to obtain this 

 result will depend on whether the footstocks of the skates 

 are level, as they ought to be, and the e.xact height will 

 vary with different individuals, depending [on whether 

 they naturally stoop or lean well back, and probably also 

 on the boots they are in the hrbit of walking in. and 

 therefore can only be determined accurately by trial ; but 

 a half-inch heel is by no means too low for most persons. 



Third. With regard to the adjustment of the skate 

 longitudinally, Figs. 4 and 5 will show the obvious effects 

 of not fixing the skate properly on the foot ; in Fig 4 the 

 skate being put too far forward, and in Fig. 5 too far 

 back. 



Having now shown how to procure the balance on any 

 desired part of the skate, it only remains to be shown 

 why the [position of the skate, with the balance on the 

 centre as in Fig. 3, is the proper one ; and as the effects 

 of the various positions are most evident in skating turns, 

 I shall confine myself entirely to them, commencing by 

 giving the theory of turns, which 1 believe has never been 

 satisfactorily explained. 



It is impossible in a few words to describe accurately 

 and fully the forces which cotne into action in making a 

 turn, but my object will be attained by describing what 

 I consider the basis of the whole theory of turns, namely, 

 that a turn is not a twist round of the body made by the 

 skater at the moment of the turn, but the turning round 

 of the body is the result of a reaction of the ice on the 

 skater caused by his putting his skate (by rolling on to 

 the toe or heel) in such a position as to make that part 

 of the skate bite or grip the ice, producing a force oppo- 

 site, though not directly opposed, to his direction of mo- 

 tion, but parallel to it. The direction of this reaction is 

 shown by the arrow a in Fig. 6, and being exerted at 

 some distance from the body, it necessarily tends to turn 

 the body round in the direction of the arrow b. It will be 

 evident that the greater the distance of the point of appli- 

 cation of this force from the curve the skater is describ- 

 ing, the greater will be the loiip/e tending to turn round 

 the body. 



This action can be shown by means of a disk of lead c, 

 in Fig. 8, with a light rod through it. If this be made to 

 roll on a table, and a force be applied to the rod at d by 

 means of the finger, the action of reversing the body and 

 preserving the same inclination will be distinctly shown. 

 Suppose the skater then about to make a back turn, and 

 that he balances near the heel of his skate as in Dove's plan, 

 then, as he can only roll a very little further back, as he is 

 already on the heel of his s';ate, the leverage, and hence 

 the couple tending to turn him round, will be almost ;///, 

 the cusp he makes being of the shape shown in Fig. 7, 

 instead of being of the shape shown in Fig. 6, and conse- 

 quently if he is to turn round in time he must give his 

 body a wrench round, which is of course very inelegant, 

 and very difficult to accomplish. If the balance is on the 

 heel the cusps of the forward turns are much larger than 

 the cusps of the back turns, thereby tending to make 

 the back turns more difficult than is necessary ; but even 

 with the balance on the centre of the skate back turns will 

 be more difficult than forward turns, as the formation of 

 our bodies prevents the bendmg up of the foot more than 

 a few degrees, even with a boot oft", whereas we can bend 

 it down 40 deg. easily. 



With the balance on the centre of the skate back turns 

 can be performed without any wrench or swing of the leg — 

 a thing that is physically impossible if the balance is on 

 the heel, as it must be in Dove's or Vandervell and 

 Witham's plan. Charles Alex. Stevenson 



JOHN DUNC.-IN: THE ALFORD WEAVER AND 

 BOTANIST 



ON the last day of 1880 the University of Aberdeen 

 was presented with a herbarium of 1131 specimens 

 of the British Flora, gathered, preserved, named, and 

 localised by an aged country weaver who lives near 

 Alford in .Aberdeenshire. He is no ordinary man, as the 

 accumul.ition of such a botanical collection is alone 

 sufficient to prove. It represents a portion only of the 

 scientific labours of nearly fifty years — for much of these 

 have been destroyed by time and the moth. This 

 remarkable man, who is now a pauper on the parish 

 which has been the scene of his uncxtinguishable scien- 

 tific enthusiasm, should be better known to the scientific 

 world, and a short sketch of his life and labours may not 

 be unacceptable to the readers of Nature. 



John Duncan was born on December 24, 1794, so that 

 he is now in his eighty-seventh year. His parents were 

 very poor, and could afford him only the merest rudiments 

 of even the three R's as then taught, for his education 

 had to be sacrificed to the pressure of penury. He learnt 

 to read by laboriously spelling his way through the text 

 in church ; his writing has ever been very rude, but dis- 

 tinct; and his spelling is such an example of the phonetic 

 as would delight Mr. Pitman. He was early sent to work 

 and became a " customer weaver," making into cloth the 

 flax and wool sent to his home by his neighbours, and 

 such he has remained ever since. He married early in 

 life, and had a son and two daughters ; but his wife died 

 more than thirty years ago, and all his family have gone, 

 he remaining as the sole survivor. During the greater 

 part of his long life he has dwelt in the valley of the Don, 

 near Alford, and for nearly thirty )ears in the same 

 cottage at Droghiburn, in the pleasant hollow of the 

 Leochel, five miles above that village. This cottage 

 forms one end of a line of dwellmgs, the other belonging 

 to a ditcher's family who prepare his simple meals. He 

 o;cupies a single room, filled with the looms and other 

 implements of his trade, open to the thatched roof, his 

 bed resting on some deals laid across the rafters, and 

 reached by means of a ladder. In this narrow space 

 John Duncan has lived for twenty-eight years, a soUtary 

 man, in serene contentment, upright and religious, work- 

 ing laboriously for an honest living, cheered only by the 

 friendship of a few, his love of books and his devotion to 

 the study of plants, which he has prosecuted with a 

 single-minded enthusiasm that is as rate as it is beautiful. 

 I visited him about three years ago and spent two days 

 in his company, having long wished to do so from what I 

 had heard of him from his dearest friend and fellow 

 student, Charles Black. I found him in good health, 

 working hard at his craft with sturdy and admirable 

 independence, visited only by a few disciples whom he 

 had inspired with a love of himself and the plants, 

 unknown, self-contained, and happy even on the verge of 

 want. I examined his plants, talked of their history and 

 the crowding memories they recalled of countless wander- 

 ings in their search, saw his books on botany, theology, 

 and general literature, which are unusually numerous and 

 costly for a poor man, conversed with him on many sub- 

 jects, chiefly connected with his studies, and his intimacy 

 with Charles, whose friend-hip is now the chief comfort 

 of his age ; and 1 left him charmed, inspired and rebuked 

 by his life, character, enthusiasm and wise contentment, 

 the result of unwearied devotion to higher pursuits. 



Some interest in the solitary student was roused by an 



