60 APPENDIX. 



distant effects ; having probably overlooked Hen- 

 ry's demonstration of that result in Silliman's 

 Journal of 1831. Hence his reference to Wheat- 

 stone. 



The effect of removing the magnet from the 

 battery is stated by Daniells as late as 1843, as an 

 elementary truth. He says: "Electro-magnets 

 of the greatest power, even when the most ener- 

 getic batteries are employed, utterly cease to act 

 when they are connected by considerable lengths 

 of wire with the battery." (Introduction to the 

 Study of Chemical Philosophy ; by Prof. John 

 Frederick Daniell, 2d Ed., 1843, chap. XVI., sec. 

 859, p. 576.) 



NOTE 0, PAGE 39. 



The Electric Telegraph : Was it invented by 

 Professor Wheatstone ? By W. F. Cooke. Part 

 II. 1856. 



NOTE P, PAGE 39. 

 16. Part I., p. 198. 



NOTE Q, PAGE 41. 



Professor Henry made a magnet for Yale Col- 

 legestill there which lifted 2,300 pounds (Silli- 

 man's Journal, April, 1831; Vol. XX., p. 201). His 

 great Princeton Magnet, now in the Scientific De- 

 partment, lifted above 3,000 pounds with a very 

 small battery. 



NOTE E, PAGE 42. 

 Vol. XIX., pp. 403-4. 



