PLATES. 



I. A Plate illustrative of Mr. White's Notice of Mr. Pbitchard's 

 Gradual Progress in the Construction of Iron Bridges 



II. A Plate illustrative of Mr. White's Design for New London Bridge. 



III. A Plate illustrative of Mr. Sturgeon's Paper on the Distribution 



and Retention of Magnetic Polarity in Metallic Bodies. 



IV. A Plate illustrative of Prof. Hare's Description of the Laboratory 



of the University of Pennsylvania. 



V. A Plate of Crow's Seaman's Octant and Traverse Worker- 



