JusE 2G, 18S5.] 



♦ KNOWLEDGE ♦ 



545 



imparted to him vanislies, having been neutralised by con- 

 tact with the earth. 



Ex. LXXXIX. — In Fig. 46 is another, ami, perhaps, 

 more useful means of illustrating the difference between con- 

 ductors and non-conductors or insu- 

 lators. R is an electrified rod held at 

 such a distance (say, two or three feet) 

 above the pieces, P, of dutch metal, 

 bran, pai>er, i&, as to be unable to 

 atTect them. Let B be a ball of metal, 

 wet worsted, or any other conductor. 

 Then, if we suspend this ball from the 

 rod, R, by a succession of dillerent 

 substances, S, such as cotton, silk, 

 wire, horsehair, itc. , we shall be able 

 to ascertain which are conductors and 

 which insulators. The lingers used to 

 hang the strings or threads on the 

 rod R should be insulated by slipping 

 over them fingerstalls, consisting of 

 pieces of indiarubber tubing. It will 

 be apparent that, if S is a conductor, 

 B will become charged, and will act 

 upon P in the same way that R 

 would, were it in B's place. In effect, 

 the interposition of the conductor, S, 

 is to bring the charge on R to the 

 position of B. 



Ex. XC. — Electrify one end, A, of 

 a glass tube, and present it to any 

 light, suspended body ; attraction ensues. Present the 

 unrubbed, i.e., unelectrified, end. A, to the suspended 

 body ; no effect is seen, because the glass beiug a non- 

 conductor, electricity remains on the part whereon it 

 is generated, instead of distributing itself over the whole 

 substance. 



Fi?. 4G. 



TO STREXGTHEX THE ARMS. 

 By Richard A. Phoctor. 



{Continued from p. 515.) 



THE biceps is strengthened by the last named exercises ; 

 but this muscle is specially strengthened by all exer- 

 cises in which weights are raised by bending the arm at the 

 elbow, and bringing the hand towards the shoulder or chest. 

 It is for this reason that bad rowing, in which the arm is 

 bent while it should be kept straight, the rower striving to 

 do with the arms the work which he should do with the 

 back and loins, develops the biceps muscle much more than 

 good rowing. For in good rowing the biceps is only at 

 work during that short and comparatively easy part of the 

 stroke towards the end, after the body has already swung 

 back to the upiight position. If the captain of a boat finds 

 that any member of his crew is developing the biceps 

 muscle too rapidly, he may be tolerably sure that there has 

 been too much arm work on the part of that oarsman at 

 any rate. If the whole crew row too much from the arms, 

 the effect on the biceps will be noticeable all round. 



Work with the hammer or mallet, especially on a vertical 

 surface, as in hammering nails into a wall, is excellent for 

 the biceps muscles, and also for the muscles at the back of 

 the upper arm. It should be distributed between the two 

 arms, however, or a marked inequality of development will 

 result Lifting weights with bent arms, pitching weights 

 over the head, and all work in which the arms are freely 

 bent, will be found excellent for developing the upper arm. 



So work done hy pulling or haidmg with straight anna 

 can benefit the upper arm in any appieciable dsgree. 



THE FOREARM AND WRIST. 



The exercise which I have found tell moat diroctly on 

 the forearm is that of lifting a chair at arm's lonsth, the 

 chair's back beiug vertical and the chair lu'Kl by a handgrip 

 on the lower rung cither of the back or front. The gup 

 required to keep the rung from slipping ensures the proper 

 action for developing the forearm, otherwise swaying up 

 dumb-bells at arras' length would be as effective ; but when 

 the grip is loosened, in the case of dumb-bells, the work 

 falls as much on the upper as on the fore arm. 



A splendid exercise for the muscles of wrists and fore- 

 arms is to hold the clubs out at arms' length hanging 

 vertically down, the palm side of the wrists being upper- 

 most, and the shoulders of the clubs next to the thumb, then 

 steadily raising the clubs to the horizontal position in a line 

 with the arms, lowering them slowly, raising them again, 

 and so on till you have had enough of the exercise. Another 

 good exercise is to raise the clubs from the same hanging 

 position to the horizontal position at right angles to the 

 arms and turned from the body, carrying them on till they 

 are vertical, then till they are horizontal again, but turned 

 athwart the body, and yet a quarter turn further till they 

 are hanging vertically down. After this carry them back 

 again to their first po'sition, repeating the double movement 

 as long as you conveniently can. 



A pleasant relief after the last exercises is obtained by 

 holding the clubs in the same hanging position, but with 

 the shoulders of the clubs next the little finger— that is, 

 daggerwise instead of sword fashion. Work the clubs from 

 this^osition to the horizontal position on either side— that 

 is, swing them as pendulums athwart the body. Again, 

 holding them rigidly at right angles to the forearm, bend 

 the arm at the elbow till the club is horizontal. Straighten 

 the arm again to the horizontal position ; then carry it down 

 to the sides and as far back as you can, still keeping the 

 club held rigidly dagger fashion. 



The broadsword exercise done with a club, first in the 

 right hand, then with the left hand, as described in the 

 preceding article, includes excellent exercise for the fore- 

 arm as well as for the upper arm and shoulders. It also 

 exercises the wrist finely, especially the parades by which 

 in actual broadsword practice the first, second, and third 

 points, are respectively met. 



I used often when a lad at Cambridge to carry in my 

 right or left hand a heavy stick, or a medium sized poker, 

 or even a club, while I walked about my room reading (not 

 always the remarkable subjects whi<'h college authorities 

 have selected in their wisdom for the life-training of men). 

 Swaying such implement about with plenty of wrist work 

 I <Tot my wrists, which were never large, so limber and 

 supple, that when I took part in singlestick encounters, I 

 could get in certain wrist strokes with a rapidity which 

 would rather astonish my opponents. In fact an ordinary 

 singlestick feels like a very light switch after a few days 

 steady use of the exercise with the heavy rods or clubs. _ 



Fencing gives good exercise to the forearm and wrist, 

 especially the movements used in the parades, and stdl 

 more especially the action in disarming an opi)onent. 

 Batting, whether at cricket, base-ball, or lawn-tennis, is 

 also good exercise to the forearm. 



THE HAND. 



The hand requires special exercises to correct the effects 

 of some of the work by which the upper arm, forearm, and 

 wrist are best strengthened. So far as gripping is con- 

 cerned nothing need be added to what has been already 



