ADDRESS OF PROF. A. M. MAYER. 489 



Let us pause here awhile from following Henry in his career of 

 discoverer and examine a little more curiously into what he has just 

 done. I said, in the beginning of this discourse, that to judge 

 rightly of a discoverer's achievements we should view them in the 

 light of the knowledge of his time. What was that knowledge? 

 I have already sketched it sufficiently to show how much Henry 

 was indebted to knowledge then existing, at least in so far as he was 

 guided thereby in his work. In this light his achievements appear 

 indeed remarkable, and as admirable as those of 'any philosopher of 

 his time. 



Simultaneously with Henry's first publication in 1827, on the 

 improvement of electro-magnetic apparatus by increasing the length 

 of the galvanic conductor and the number of its coils, Ohm published 

 at Berlin, his mathematical law of galvanic circuits, in a book entitled 

 Galvanische Kette, mathematisch bearbeitet. This publication was 

 not only received with indifference, but almost with contempt by his 

 countrymen. Professor H. W. Dove, of Berlin, says that " In the 

 Berlin Jahrbucher fur wissenschaftliche Kritik, Ohm's theory was 

 named a web of naked fancies, which can never find the semblance of 

 support from even the most superficial observation of facts ; ' he who 

 looks on the world/ proceeds the writer, 'with the eye of reverence 

 must turn aside from this book as the result of an incurable delusion, 

 whose sole effort is to detract from the dignity of nature.' " 



Henry's researches were based avowedly on a thoughtful study 

 of the work and theory of Ampere in 1820-'21, and of the galvan- 

 ometer of Schweigger, (of the same date,) as applicable to the electro- 

 magnet of Sturgeon in 1825 ; and his series of ingenious experi- 

 ments during the years 1828-'30, were then completed by the full 

 announcement of his discoveries, January 1, 1831. At that time, 

 no writer or physicist appears to have had any just conception of 

 the consequences flowing from Ohm's announcement, particularly 

 of that most important deduction, viz : that the interpolar resist- 

 ance should equal the internal resistance of the battery, in order to 

 obtain the maxima of electro-magnetic effects. This theory or 

 law of Ohm, utterly neglected at home, unknown to Wheat- 

 stone, to Faraday, or to Roget, could hardly make its way abroad 

 in the garb of a foreign tongue, and reach Henry in Albany. Henry 



