. St. Nicholas [serial] . et for the width of the bridge,and extend out 2J/2 feet on each side. From inch and larger stuff it can be made twelvefeet long, and longer with heavier can use single two-by-four timbers on eachside up to twelve feet in length. In the one-post bridge you divided the tri-angle in two by means of the vertical middlepost. The two-post bridge looks as thoughyou had moved these two smaller trianglesapart and joined their tops with a timber. The side of this bridge, then, is in threeparts, of equal length. The first part on eachside is a triangle, like the half
. St. Nicholas [serial] . et for the width of the bridge,and extend out 2J/2 feet on each side. From inch and larger stuff it can be made twelvefeet long, and longer with heavier can use single two-by-four timbers on eachside up to twelve feet in length. In the one-post bridge you divided the tri-angle in two by means of the vertical middlepost. The two-post bridge looks as thoughyou had moved these two smaller trianglesapart and joined their tops with a timber. The side of this bridge, then, is in threeparts, of equal length. The first part on eachside is a triangle, like the half of the triangleof the one-post. And to get the length of thelong side of this triangle (the slanting side isthe long one in this case), you square twothirds of the length of the bridge, divide bytwo and take the square root of the gives the length of the slanting pieces ofthe triangles at each end of the side. Supposeyou wanted a 12-foot bridge: 8 is 2/3 of 12; 1920.] ONE-, TWO-, AND THREE-POST BRIDGES 735. the square of 8 is 64; half of 64 i? 32, andthe square root of 32 is, roughly, 5 feet 7 B gives a better idea than can begiven by words. Such a bridge is quite you make the floor in the same fashion,only now you have tzvo posts on each side, sothere must be hvo extra-long crosspieces com-ing where these posts are fastened to the braces must be run from the ends ofthese long crosspiecesto the tops of the posts,thus keeping the sidesrigid. The photograph givesa good idea of the two-post bridge. This wasmade in about fortyminutes by the lads inthe picture. And thatbrings us to the THREE-POST BRIDGE This one reminds youmuch of the two-post,only the middle section,which was a rectanglewith the two-post, hasbeen lengthened outconsiderably, so thatthere must be a third post, this one connecting the middle of thefloor-timber with the middle of the brace con-necting the tops of the two end triangles. You see that now the side is di
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Keywords: ., bookcentury1800, bookdecade1870, bookidstnicholasserial4721dodg
