86 



• KNOWLEDGE 



[June 1G, 



f.-jm the el>onite caps for the sake of clearness. The olyect 

 o! the slot (E) ia to allow of the alteration of the point 

 of contact between the hnishes and the coninintator— a 

 jiecessary feature, as will lio seen by experience. 



One of the most important points in connection with an 

 dectrie generator is the motive power. This may take the 

 Torm of a treadle or an ordinary niultiplyin-^ wheel turned 

 by hand. To a great extent, we must leave the arrange- 

 ment of this matter with the experimentalist ; but the 

 wheel should be as far as possible from the armature, say 

 18 inches, tiie wooden base, where a multiplying wheel is 

 used, being about 14 inches by -21 inches. It may be 

 pointed out, however, that the" width is not necessarily 

 the same throughout. Owing to the sinallness of the 

 armature pulley-wheel, an endless gut-band is requisite, 



but some arrangement to compensate for its stretching 

 ia essential. Fig. 12 illustrates a simple device ; D 

 repre-sents a standard 1 inch thick, if of wood, h an 

 inch if of metal, through which passes a shaft A B, of 

 the section .shown, cut from a live-eighth rod to half-an- 

 inch in diameter at each end. It is provided with a screw 

 thread at the extremity A, and a slot like that on a screw- 

 head at B, a pin (C) being driven through to hold alight metal 

 or wooden wheel (OG) 9 to 12 in. in diameter, in position, 

 surticient freedom being allowed for the wheel to revolve 

 easily. E is a nut, .screwed on at A, to pull AB tight 

 up to the bo.s.s F. On first adjusting the band, the end 

 (I{) of the shaft should be turned towards the machine. As 

 tlie band stretches, B should be gradually turnc'd towards 

 the remote side, thus increasing finally the distance 

 Ijotwct'n the centres of tlie wheel and the armature by a 

 ■<|uarter of an inch. 



\\' 



now TO GET STRONG. 



(Conlimu;rI.) 



TE have first to notice that it is by no means neces- 

 sary, as many imagine, to give much time daily to 

 <xerci:e in order to acquire a strong and hearty body. On 

 til", coutrary, many who, dissiitisfied with the condition of 

 their health and strength, have begun to take more exercise 

 thin before, have defcat'jd their purjmso by taking too much 

 exircise. To exhaust the frame by long walks and rides, 

 o- by undertaking some difficult and arduous system of 



training, would be unwise, even if the sole object were to 

 acquire strength; but where the ultimate object is to 

 increase the capacity for the work of life, and this work 

 is only indirectly dependent on bodily strength, it is next 

 door to madness to exhaust the frame by ellbrts for which 

 it is unfit 



Let it be noticed, then, that apart from such exercise as 

 falls naturally into the day's work, an hour a day, or even 

 four times a week, devoted to systematic exercise, will 

 sutttce first to restore and afterwards to maintain the 

 strength of the body. It was with this small amount of 

 daily training that Maclaren attained such rejiarkable 

 results, adding girth to the chest and limbs, increasing the 

 weight and muscular development, changing actually the 

 shape of the bony framework of the body, — in grown 

 men,— not in long periods of time, but in a few weeks. 



Next it is to be noticed that for successful efforts in this 

 direction we do not want heavy dumb-bells and clubs, or 

 gymnastic apparatus for the achievement of ditlicult feats. 

 No apparatus at all is, indeed, absolutely necessary, but 

 light dumb-bells (from 31b. to 61b.) may be used with ad- 

 vantage, and light clubs are still better ; while by sotne 

 simple contrivances, costing a few shillings, a bed-room, 

 Iv.ith-rooni, landing, or hall, as may be convenient, may be 

 turned into a temporary gymnasium, containing everything 

 necessary for exercising every muscle of the body. It is 

 always well, however, to include among the exercises some 

 N\ hich require a certain degree of practice for their proper 

 iiccomplislnnent, as this gives interest to the work. For 

 tills reason, ball-play (outdoor or indoor) was deservedly 

 :i)>l)r(i\((l by ancient physicians. Fencing, single-stick, and 

 oilier such encounters are good, if entered upon with due 

 niudcnition, both as to time and as to the spirit with which 

 they are carried on. 



First and foremost in all exercises comes the develop- 

 ment of the chest, because this development means the 

 increase of lung-power and heart-power, improvement in 

 the breathing, and in the circulation. Scarce one in a 

 hundred among men in middle life has his breathing 

 apparatus in respectable ordci'. A man in good health 

 ought to be able to run a mile at a moderate pace without 

 inconvenience. But how many can do this? We do not 

 invite paterfamilias to try the experiment, unless he is 

 prepared to stoja tin* trial so soon as he is satisfied that he 

 cannot run the mile vnfhout inconvenieiu-e. For there; is 

 ■Janger in the experiment, if the question is whether, by 

 sheer endurance, ho can get through thi; mile at any pace 

 resembling a run. Let any man, even as young as twenty- 

 fi\e or thirty, who has let day after day pass for several 

 years without duly exercising his chest, content himself by 

 running until it would be distressing to him to continue 

 the exercise : he will vciry quickly recognise how much 

 beyond his power running a mile, without distress, has 

 become,— entirely through his neglect of daily exercise. 



Not a day should be allowed to pass without exerci.se by 

 which— at least three times each day— every air-cell of the 

 lungs has been filled to its utmost capacity. Once, at 

 least, each day this should be done by active exertion, such 

 as a sharp, but not distressing, run, increasing gradually 

 until two or thn^r; hundred yards are covered at full speed, 

 or from half a mile to a mile at a steady swing. But any 

 run long enough to set the lung bellows actively at work 

 will suffice for this purpose. Instead of running, however, 

 some may prefer sparring. This is capital exercise for the 

 chest, and is good also for the arms and shoulders. A live 

 opponent is not needed— in fact, i-s not desirable ; for where 

 there is one the exercise is apt to be continued too long, 



