1858.] Electric Telegraph in relation to Science, 669 



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 un- 

 objectionable in respect of any resistance they might offer to 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 motion. 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 rotatory rachet 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 when it is twisted about in the hands, or placed 

 on board a ship or in a railway carriage, as when fixed immovably. 

 Where it is possible, as in the vibratory needle, the moving parts 

 are brought near to the centre of motion, that the inertia of the 

 portion to be moved, or the momentum of that to be stopped, should 

 be as small as possible, and thus great quickness of indication 

 obtained. All this delicacy of arrangement and workmanship is 

 introduced advisedly ; for the inventor, whom I may call the 

 student here, considers that refined and perfect workmanship is 

 more exact in its action, more unchangeable by time and use, and 

 more enduring in its existence, than that which being heavier must 

 be coarser in its workmanship, less regular in its action, and less 

 fitted for the application of force by fine electric currents. 



Now there was no chance 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 acqubition of the 

 knowledge of others or by increase of it through its own exertions, 

 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 beginnings, 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 differ- 

 ences almost approaching the infinite : for the small as often con- 

 tains the great in principle as the great does the small ; and thus the 



