668 Transactions of the American Institute. 



portation of those who have been operated on, from ambulance to 

 hospital, on the part of each nation is formally installed only in 

 the United States. 



INSTANTANEOUS PHOTOGRAPHr. 



A correspondent of The Camera Obscura remarks that the pro- 

 duction of instantaneous photographs depends upon the excellence 

 of the apparatus and chemicals employed, and rapidity of manipu- 

 lation, rather than on the practice of any theory or process. The 

 plate should be exposed as soon as possible after its exit from the 

 silver bath, and developed immediately after exposure. The object 

 to be photographed must be lighted as strongly as possible, and 

 if direct sunlight is not present, all false lights and reflections are 

 to be carefully avoided. March and October are the most fav- 

 orable months for instantaneous photography. 



THE GREAT BRmGE OVER THE EAST RIVER. 



The company chartered by the last New York Legislature to 

 connect New York and Brooklyn b}^ a bridge, are rapidly making 

 arrangements to commence this work. The plan is to erect a sus- 

 pension bridge from a point on the elevated ground north of Fulton 

 street, Brooklyn, to a point near the City Hall Park, in New York, 

 the whole distance being about 5,860 feet, less than one-half of 

 which is over the water, the remaining part being required to place 

 the bridge at such a height as not to interfere with navigation. Its 

 width is to be eighty feet, widened at each terminus to one hundred 

 feet. It will have two roadways for carriages and carts, two rail- 

 ways for cars, and an elevated promenade, sixteen feet wide, for 

 foot passengers. The cars will be drawn across in three minutes 

 by wire ropes connected with stationary steam engines. This great 

 undertaking, estimated to cost $6,000,000, will not be completed 

 in less than five years. 



DYNANOMETER FOR LOCOMOTIVES. 



M. E. Holtz, engineer of the Prussian State railway, has invented 

 an apparatus for registering the tractive force of locomotives during 

 the whole of each trip with a train. It consists of a set of com- 

 pound levers, which transmit the tractive force to a spiral spring. 

 A long sheet of paper passes over two rollers, which move at a 

 uniform rate by means of clock work, carrying the paper in a ver- 

 tical direction. The graduations on the paper in one direction 

 represent time, and those at right angles to the first show the force 



