AuaANDKR AND Ja(.kson — Poli/gons to Generate Diagrams, Sj-c. 23 



They ai-e thus lettered on fig. 2a, though drawn flatter to save space. The 

 nortli-south pair acts tovjards the rib, their algebraic value being -,, so that 



,,3 



atSandiS^' wehavea Aooj:; thrust . The east-west pair acts oAvay from the rib, 

 so that at A and A' there is a lioop tension of -. 



A/lass ^T. \b 



balanced by conjugate loads 



Alexander & Jackson 



JliP Load at ecccTiJ-^^uT^ "TL ^ 

 /lil isShejoo^r offiynci/yal 

 Strossrs c<''m/'fU'/'() 



Fig. la. 



It is readily proved that the shaded portions of the stress areas P and Q, 

 on the arc AB, just as in the former case, are proportional to sin and cos %, 



,,,3 



where % is the slope of the curve at B. Thus - F = P = ^ sin Q cos 2^, and 



if = (> = ^ cos cos 20, giving the hoop tension at i> = ^ cos 20. With 

 successive values of 0, we have hoop tension on the rib from A to the middle 



