cxcii GENERAL SUMMARY OF SCIENTIFIC AND 



was constantly receiving applications for devices already 

 secured by letters patent. 



The great importance of a thorough digest, published in 

 convenient form, of each one of the one hundred and fortv- 

 five classes of inventions for the convenience of examiners, 

 inventors, and attorneys is strongly urged. The need of 

 additional room is also dwelt upon. 



ENGINEERING AND MECHANICS. 



In this department there are many items of interest to 

 record concerning the progress of the year just passed. The 

 great steel bridge across the Mississippi River at St. Louis, 

 together with the tunnel forming part of its western ap- 

 proaches, is finished, and was formally opened for railway 

 traffic with much ceremony on July 4th. The strength of 

 the structure was shortly thereafter tested by moving out 

 abreast and simultaneously over each one of the three spans 

 two trains of seven locomotives each. Tiie results of the 

 test agreed very closely with the theoretical computation, 

 and the trial proved highly satisfactory. The work upon 

 the great suspension bridge to span the East River between 

 New York and Brooklyn has progressed but slowly, owing to 

 complications of a legal and financial character. The Brook- 

 lyn tower was completed on the 16th of December, 1874. 

 The anchorage on the Brooklyn side is also in a forward state. 

 When completed, this will be the largest suspension bridge in 

 the world, the clear span between the towers being 1600 feet. 



The railway tunnel through the Musconetcong Mountain 

 in Northern New Jersey, an engineering work of considera- 

 ble magnitude, was practically finished by the union of the 

 two headings on the 16th of December. The tunnel proper 

 is over a mile in length, with long open cuts at each end. The 

 road of which the tunnel is part is an extension of the Lehigh 

 Valley Railroad, and the tunneling has been progressing for 

 more than two years. 



The system of underground railways, so long in successful 

 operation in a number of European capitals, and affording 

 the only rational solution of the problem of railway transit 

 through populous cities, is about to receive an important ex- 

 tension in this country. In our last yearly Record we com- 

 mented upon the completion of the Baltimore underground 



