340 HENRY AND THE TELEGEAPH. 



impartocT to an elQctro-vaagnetintf^TYtosed. in a long circuit," — that "the attraction of a 

 piece of iron by an electro-magnet could not be made available in circuits of very 

 great length," excludes absolutely and forever, all possibility of competitive claim to 

 a discovery admittedly "the most important i)oint of all" in the practical develop- 

 ment of a real telegraph; — the discovery of the "intensity" magnet. Undoubtedly re- 

 quired to institute especial experiments in order to properly proportion his magnet 

 and battery, Wheatstone was led by self-esteem to entirely overestimate the original- 

 ity of such experiments, and correspondingly to underrate the value of Henry's in- 

 structions or suggestions. 



Eecurring to his plan of a terminal secondary circuit Professor Wheatstone re-iter- 

 ates in the same document: "Having convinced myself that it was hopeless to expect 

 to ring an alarum by the direct action of the electric current through a circuit of 

 great length on an electro-magnet as ordinarily constructed, I began to think whether 

 the effect required might not be produced in an indirect manner. It occurred to me 

 that the difficulty would be overcome if a short circuit in which the electro-magnet of 

 the alarum and a rather powerful electro-motor should be interposed, could be com 

 pleted and broken at will by some action governed by the current in the long circuit. 

 . . . These methods of completing the secondary circuit have lost all their impor- 

 tance and are scarcely worth contending about, since my discovery that electro-magnets 

 may be so constructed as to produce the required effects by means of the direct cur- 

 rent, even in very long circuits." 



Again returning to this fatal theme, he repeats (having resolved to "carry oiit his 

 investigations alone" without the co-operation of Mr. Cooke), "After this resolution 

 had been taken, I commenced a series of researches on the laws of electro-magnets, and 

 was fortunate enough to discover the conditions {which had not hitherto been made the 

 subject of philosophical inquiry) by which effects could bo produced at great distances. 

 This rendered electro-magnetic attraction for the first time ap])licable in an imme- 

 diate manner to telegraphic purposes." * — Notwithstanding that Henry, in 1830, 

 had demonstrated — and on the first of January, 1831, had confidently announced to 

 the scientific world, that his own original "intensity" magnet with a "trough" 

 battery, was "directly applicable to the project of forming an electro-magnetic tele- 

 graph " ! 



This redundant iteration of original discovery, this reticence as to any similar 

 investigation known to have been even attempted by Henry, scarcely permits the 

 charitable suggestion of " unconsciousness." That his persistent claim should have 

 mivsled his colleague, Professor Daniell, into incorporating in the text of his new 

 edition of the " Cheu\ical Philosophy" the following laudation, is perhaps not alto- 

 gether to be wondered at: "Ingenious as Professor Wheatstone's contrivances are, 

 they would have been of no avail for telegraidiic purposes without the investigation 

 {which he was the first to make) of the laws of electro-magnets when acted on through 

 great lengths of wire."t Were the name of Henry inserted in the italicised i)areu- 

 thesis, the proijosition stated would be beyond the reach of cavil or exception. In- 

 genious as Professor Wheatstone's contrivances were, they would have heen, of no avail 

 for telegraphic purposes, without the investigation (which Hexry was the first 

 to make) — of the laws of electro-magnets when acted on through great lengths of 

 wire. 



Mr. Cooke (to whom probably even the existence of Henry was unknown) makes 

 the very expressive comment on the above passage from the " Chemical Philosophy" 

 of the professor at King's College : " Mr. Daniell might have added that this investi- 



*" Professor Wheatstone's Case," as above cited, sect. 30(), 314, and 333, pp. 94,96, 

 and 100. 



i Introduction to the Study of Chemical Philosophy, second edition, 1843, chap, xvi, 

 sect. 859, p. 576- 



