. Edinburgh New Philosophical Journal. 310 Mr Sang on the Construction of Oblique Arches. The horizontal plan of the jomt is still a double logarithmic curve; and its delineation, including, of course, that for the circular arch, is as follows. EF being, as before, the plan of one of the lines of pres- sure, find HQ a F's- 3- third proportional to the horizontal and the vertical semi-axis; through Q draw Q'E paral- leltoHG. Describe then logarithmics having E'G for their common sub- tangent, and having their ordinates parallel to E'H, the bisec- tion of the interval between these Avill give th
. Edinburgh New Philosophical Journal. 310 Mr Sang on the Construction of Oblique Arches. The horizontal plan of the jomt is still a double logarithmic curve; and its delineation, including, of course, that for the circular arch, is as follows. EF being, as before, the plan of one of the lines of pres- sure, find HQ a F's- 3- third proportional to the horizontal and the vertical semi-axis; through Q draw Q'E paral- leltoHG. Describe then logarithmics having E'G for their common sub- tangent, and having their ordinates parallel to E'H, the bisec- tion of the interval between these Avill give the horizontal pro- jection of the joint. Similarly, the side and end projections are modifications of those belonging to the circular arch:— they are fully investigated in the appendix. Having obtained a tolerable approximation to the forms of the arch-stones, it is not uncommon for bridge-builders to throw the remaining responsibility on the abutments, which, besides transmitting the pressure, have to continue its distri- bution among the parts of the pier. In truth, the principles of equilibrium seem never, even in the case of the right arch, to have penetrated beyond the facing stones of the piers; and the effect of the arrangement in every bridge which I have seen, or the drawings for which I have inspected, is to throw the whole weight of the arch on the outside stones of the pier and on the outer row of piles in the foundation. To see this clearly, let us draw one of the abutment stones of a right bridge. The oblique face AB re- ceives the pressure of the lowest vous- soir; and it ought to receive that pres- sure perpendicularly. But the stone is prevented from yielding by resistances against the sur- faces CD. DE: the pressm-e of the voussoir is thus decom- posed into two pressures, one against CD, well known to. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these
Size: 1626px × 1536px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., 1840, bookcentury1800, bookcollectio, bookdecade1830, bookyear1839
