338 THE PRESIDENT S ADDRESS. 



elsewhere, for upon tliem, after exposure to the action of salt 

 water for centuries, the surface remains completely unchanged. 



Of course where great friction occurs, such as that to which 

 rails and iron wheels are exposed, not only the coating, but the 

 material itself will necessarily wear away. 

 The Telephone. 



The discovery of that wonderful sound-transmitting instrument, 

 the Telephone, is one of the most remarkable of the present age. 

 Professor A. Graham Bell, of Salem, Massachusets, America, has 

 the credit of the first discovery ; and has proved that the intona- 

 tions of the human voice can be transmitted to a distance of 143 

 miles by his last experiments. 



Mr. Bell is a professor in the Boston University, and one of 

 his departments is said to be " vocal physiology." It is five years 

 since his attention was directed to the subject, and nearly two 

 years since he made experiments on a wire from Eoston to Cam- 

 bridge, 2 miles apart ; and he took out his patent about 15 months 

 ago. In October, 1876, conversation between the operator and 

 the professor, 2 miles apart, could be distinctly heard, the dialogue 

 being carried on in the ordinary tones of voice. The next ex- 

 periment was made 18 miles apart, from Boston to Salem, when 

 not merely words in sound were transmitted, but distinct tones 

 and infiexions, so that the various voices of the speakers were 

 recognized, and songs were heard with distinctness, the same 

 effect being produced as if the listener were at the rear of a 

 large concert hall. The latest achievments by Professor Bell's 

 instrument is the transmission of music and various sounds 

 between Boston and North Conway, in New Hampshire, a dis- 

 tance of 143 miles. 



I will noAV endeavour to describe this wonderful instrument, 

 and to illustrate it with a drawing, which description and draw- 

 ing, through the kindness of Dr. Le Neve Poster, I have taken 

 from an American Engineering Journal. 



The transmitting instrument consists of a horizontal electro- 

 magnet, attached to a pillar about 3 inches above a horizontal 

 mahogany stand. In front of the poles of this magnet, or more 

 correctly speaking, magneto-electric-induetor, is fixed to the stand 

 in a vertical plane a circular brass ring, over which is stretched 

 a membrane, carrying at its centre a small oblong piece of soft 

 iron, which plays in front of the inductor magnet whenever the 



