Description of a Frame Bridge. 123 



It has occurred to me, and I would suggest that great advantage 

 and economy in the process of burning would arise, if the interstices 

 between the different layers of bricks in the kiln were filled with small 

 coal, thus assisting in thoroughly and uniformly burning all parts of 

 the brick and improving their quality. It appears to me that no dan- 

 ger would attend this method, nor would vitrification take place if 

 proper care was taken 5 this practice prevails in England, where the 

 coarser cinders, which are not allowed to pass through in skreening, 

 are constantly made use of, by strewing them between contiguous 

 layers of the brick, as they are built up, tier upon tier, in the kiln, 



I have thus endeavored to lay before the pubUc the principal details 

 of this new process in brick making, the advantages of which can 

 scarcely as yet be duly appreciated ; further experience in the use of 

 it will doubtless tend to render it more perfect. It appears to me 

 however sufficiently decided, that by adopting the use of anthracite 

 coal, in the manner pointed out, a saving of time and expense may 

 hereafter be calculated on, suflScient to reduce the price of this indis- 

 pensable article in building nearly fifty per cent., besides rendering 

 their texture and quality superior to those which have heretofore 

 been manufactured in this country. 



Art. XXII. — Description of a frame Bridge; by Geo. W. Long, 

 Lieutenant United States Artillery. 



(Communicated for this Journal.) 



Fort Jackson, January 30th, 1830. 



TO THE EDITOR. 



Sir — I offer for the American Journal of Science and Arts, the 

 following description of a frame Bridge, which I claim as my inven- 

 tion, and which I have taken measures to secure to myself by 

 letters patent in the U. States. 



The object of the invention is to secure in a frame work some of 

 the most essential properties of a solid beam ; such as gaining strength 

 by great depth of beam, and using great economy in material, by re- 

 ducing the beam to such a shape that it will be equally strong through- 

 out. The latter property is of material consequence in beams of 

 great length, as for bridges, whose weight of material would be near- 

 ly a load for the bridge. In a solid beam of uniform width, the act- 



