AMERICAN INSTITUTE. 623 



through the ocean in one hour, i. e. sound 1,140 feet per second, 

 gives 4,400 for the velocity by water, which exceeds three thou- 

 sand miles. 



The American Franklin ^'eripuit ccelofulme?!,''' &c. The Ame- 

 rican Morse made the fulmen go by sea. 



ELECTRO MAGNET. 



The mass of iron is of little importance compared witli the sur- 

 face, and amount of wire around it, so that it is best to make 

 them holloio, for the sake of greater lightness and convenience. 

 The increase of power has a limit — that is, the size of the wire 

 and number of coils around the helix. The hollow magnet must, 

 however, have considerable thickness, never less than one quarter 

 of the radius of the cylinders. 



Mr. Chairman called up the regular subject, and requested Mr. 

 Fisher to present his views of the mechanical means to relieve 

 the travel in Broadway. 



Mr. Fisher complied, as follows : 



I wish to say a few words upon two plans which were brought 

 forward at our last meeting — that of Mr. Leonard, and that which 

 I understand to be the plan of the public authorities, which the 

 chairman mentioned. 



The plan of a railroad with an edge rail upon the edge of the 

 side-walk, with a wheel so formed that only this rail will be 

 needed to guide the car, and a flat rail for the outer wheel, will 

 have the great advajitage that it will offer no obstruction to ordi- 

 nary vehicles. But I prefer the plan which I have often men- 

 tioned as the best for a railroad on the ground, if any be laid, 

 which I have not recommended. This plan is to have both rails 

 flat, and flush with the pavement, and laid on the middle of the 

 street. All vehicles would be benefited by this; and there 

 would be no necessity for that worst of all vehicles, the city car. 

 But it would be incomparably better to make the whole surface of 

 iron; and to avoid the excessive roughness which mai\y deem 

 necessary for iron pavements. lam satisfied, from having seen 

 thousands of horses run on stones as smooth as our side-walks, 

 that on a level, they could run on smooth iron, and that on 

 inclines much less roughness than is supposed would be needed. 

 The forms of paving proposed by Mr. Nowlan and Mr. Tillman 

 are sufiiciently rough for any inclines in this city; and yet they 

 are so designed that a wheel of two inches width would not at 

 any time go below the level of the upper surfaces. 



While I am on this point I will offer a suggestion, hoping it 



