254 LITER ATTIRE UPON THE CONTINUOUS GIRDER. 



GREEKS, CHAS. E. "Graphical Method for the Analysis of Bridge 

 Trusses." Van Nostrand. 1875. [Force and equilibrium polygons are 

 used, but the moments at the supports are found by an original method of 

 approximation, or "balancing of moment areas.'} 



HERSCHEL, CLEMENS. " Continuous, Revolving Drawbridges." Boston, 

 1875. [The formulae of Weyrauch are made use of. The case of " second- 

 ary central span " is for the first time investigated, and the appropriate 

 formulae given. The fact that the live load reactions for supports out of 

 level are unchanged, provided the dead load reactions are zero, is also for 

 the first time clearly stated. The draw span is thoroughly treated, and the 

 idea of weighing off the reactions at the piers of a continuous girder sug- 

 gested.] 



MERRIMAN, MANSFIELD. " Upon the Moments and Reactions of the 

 Continuous Girder" Journal of the Franklin Inst for March and April, 

 1875; Van Nostrand's Eng. Mag., July, 1875, August and Sept., 1876; 

 London Phil. Mag., Sept., 1875, " On the Theory and Calculation of Con- 

 tinuous Bridges," D. Van Nostrand, New Tork, 1876, 16mo, pp. 180 ; as 

 well as the formulae contained in Chapter XII. of this work. [By the aid 

 of the properties of the Clapeyronian numbers, Mr. Merriman has deduced 

 new and general formulae eminently suited for practical use. Also relations 

 are deduced from which tables for moments and reactions may be drawn 

 up to any desired extent by simple additions and subtractions, indepen- 

 dently of the general formulae. (See Chap. XII.) The simple girder 

 appears as a special case of the continuous girder. The formula) are, in 

 respect to simplicity and ease of application, superior to any heretofore 

 given.] 



