27 OF ENGINEERING FOBMULÆ.
Annealing iron wire diminishes its strength.
High temperature in casting is injurious to gun-
metal.
• Plated webs are more economical than braced
webs in shallow girders or near the ends of long
girders. In small lattice girders it is better to
make the lattices uniform throughout.
Stbength of Iron.
Breaking Weight.
Name. Description. Specific Gravity. Tensile. Trans- verse. a 1 a .2 ■ 3- § g H | O
Stockton-on- Tees .. Hematite Co. Weardale Co. Butterley Co. Lord Ward’s Blaen Avon Dr. Price’s .. Mean of No. 3 pig .. .. No. 2 pig .. .. No. 3 pig .. .. No. 3 pig .. .. Cold-blast pig .. Cold blast No. 1 Improved (P) .. 51 samples .. T-135 22271 6932 6305 87063 7-214 17958 5538 5299 82265 7-158 21859 7374 6369 939*9 7-126 23265 6692 6940 91661 7-052 25872 6992 6833 94077 7-137 25456 8873 5966 95775 7-259 28960 9120; — i — 7*140 23257 7102 6056 91061 1 |
The breaking weights above are reduced to
lbs. per square inch. The transverse breaking
weight represents the strain necessary to break a
bar 1 inch square projecting horizontally 1 inch
beyond the point of support, the weight being
applied at the outer end.—Ordnance Experiments.
Shearing or Oak Tbeenails (Dockyard Experiments').
Diameter of treenails, inches.. 1 li If
Shearing force, tons .. .. 1’6 2'3 2‘95 3’9
Tons per square inch of section 2’03 1’88 1’67 1*62