To return to the spacing of rods in the bottom of a T-beam; the report of the Joint Committee advocates a horizontal spacing of two and one-half diameters and a side spacing of two diameters to the surface.  The same report advocates a “clear spacing between two layers of bars of not less than 1/2 in.”  Take a T-beam, 11-1/2 in. wide, with two layers of rods 1 in. square, 4 in each layer.  The upper surface of the upper layer would be 3-1/2 in. above the bottom of the beam.  Below this surface there would be 32 sq. in. of concrete to grip 8 sq. in. of steel.  Does any one seriously contend that this trifling amount of concrete will grip this large steel area?  This is not an extreme case; it is all too common; and it satisfies the requirements of the Joint Committee, which includes in its make-up a large number of the best-known authorities in the United States.

Mr. Thacher says that the writer appears to consider theories for reinforced concrete beams and slabs as useless refinements.  This is not what the writer intended to show.  He meant rather that facts and tests demonstrate that refinement in reinforced concrete theories is utterly meaningless.  Of course a wonderful agreement between the double-refined theory and test can generally be effected by “hunching” the modulus of elasticity to suit.  It works both ways, the modulus of elasticity of concrete being elastic enough to be shifted again to suit the designer’s notion in selecting his reinforcement.  All of which is very beautiful, but it renders standard design impossible.

Mr. Thacher characterizes the writer’s method of calculating reinforced concrete chimneys as rule-of-thumb.  This is surprising after what he says of the methods of designing stirrups.  The writer’s method would provide rods to take all the tensile stresses shown to exist by any analysis; it would give these rods unassailable end anchorages; every detail would be amply cared for.  If loose methods are good enough for proportioning loose stirrups, and no literature is needed to show why or how they can be, why analyze a chimney so accurately and apply assumptions which cannot possibly be realized anywhere but on paper and in books?

It is not rule-of-thumb to find the tension in plain concrete and then embed steel in that concrete to take that tension.  Moreover, it is safer than the so-called rational formula, which allows compression on slender rods in concrete.

Mr. Thacher says, “No arch designed by the elastic theory was ever known to fail, unless on account of insecure foundations.”  Is this the correct way to reach correct methods of design?  Should engineers use a certain method until failures show that something is wrong?  It is doubtful if any one on earth has statistics sufficient to state with any authority what is quoted in the opening sentence of this paragraph.  Many arches are failures by reason of cracks, and these cracks are not always due to insecure foundations.  If Mr. Thacher means