100 ANNUAL OF SCIENTIFIC DISCOVERY. 



signs of action, new or old ; to nurse them up by any means until they have 

 gained strength ; then to study their laws, to eliminate the essential condi- 

 tions from the non-essential, and, at last, to refine again, until the encum- 

 bering matter is as much as possible dismissed, and the power left in its 

 highly developed and most exalted state. The alterations or successions of 

 currents, produced by the movement of the keeper at the communicator, 

 pass along the wire to the indicator at a distance; there each one for itself 

 confers a magnetic condition on a piece of soft iron, and renders it attractive 

 or repulsive of small, permanent magnets ; and these, acting in turn on a 

 propelment, cause the index to pass at will from one letter to another on the 

 dial face. The first electro-magnets, i. e., those made by the circulation of 

 an electric current round a piece of soft iron, were weak ; they were quickly 

 strengthened, and it was only when they were strong that their laws and 

 actions could be successively investigated. But now they were required 

 small, yet potential. Then came the teaching of Ohm's law; and it was 

 only by patient study, under such teaching, that Wheatstone was able so to 

 refine the little electro-magnets at the indicator as that they should be small 

 enough to consist with the fine work there employed, able to do their 

 appointed work when excited in contrary directions by the brief currents 

 flowing from the original common magnet, and unobjectionable in respect 

 of any resistance they might offer in the transit of these tell-tale currents. 

 These small transitory electro-magnets attract and repel certain permanent 

 magnetic needles, and the to-and-fro motion of the latter is communicated 

 by a propelment to the index, being there converted into a step-by-step mo- 

 tion. Here everything is of the finest workmanship; the propelment itself 

 requires to be watched by a lens, if its action is to be observed ; the parts 

 never leave hold of each other; the vibratory or rotary ratchet-wheel and 

 the fixed pallets are always touching, and thus allow of no detachment, or 

 loose shake; the holes of the axes are jewelled; the moving parts are most 

 carefully balanced, a consequence of which is, that agitation of the whole 

 does not disturb the parts, and the telegraph works just as well Avhen it is 

 twisted about in the hands, or placed on board a ship, or in a railway car- 

 riage, as when fixed immovably. 



Now there was no accident in the course of these developments ; if there 

 were experiments, they were directed by the previously acquired knowledge; 

 every part of the investigations was made and guided by the instructed 

 mind. The results being such (and like illustrations might be drawn from 

 other men's telegraphs, or from other departments of electrical science), 

 then, if the term education may be understood in so large a sense as to 

 include all that belongs to the improvement of the mind, either by the acqui- 

 sition of the knowledge of others, or by increase of it through its own exer- 

 tions, we learn by them what is the kind of education science offers to man. 

 It teaches us to be neglectful of nothing; not to despise the small begin- 

 nings, for they precede, of necessity, all great things in the knowledge of 

 science, either pure or applied. It teaches a continual comparison of the 

 small and great, and that under differences almost approaching the infinite: 

 for the small as often contains the great in principle as the great does the 

 small; and thus the mind becomes comprehensive. It teaches to deduce 

 principles carefully, to hold them firmly, or to suspend the judgment to 

 discover and obey law, and by it to be bold in applying to the greatest what 

 we know of the smallest. It teaches us first by tutors and books to learn 

 what is known to others, and then, by the lights and methods which belong 



