Page:Great Neapolitan Earthquake of 1857.djvu/199

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TABLE OF FACTORS FOR COEFFICIENT.
151

The use of the coefficient , in Eq. XXI. et seq., considers the value of (Eq. ) evanescent, so that the prism at the moment of fracture has not risen through an appreciable angle, at the surface of fracture, and from the extremely small extensibility of mortar, stones, &c., this is sufficiently true to nature.

Table I.

Factors for the coefficient .

Material 1. Weight in pounds per cub. foot
Sp. gr.
2. Pounds per square inch
Resistance to Pressure.
3. Pounds per square inch
Resistance to Tension.
3. Authority for 1 and 2.
Limestone, Caserta, Naples 170 8173 908 Rondelet
Upper Limestone, Geneva 169 4917 546 Gauthey
Jurassic Limestone, Givry 148 4232 496 ..
Cretaceous Limestone (Compeigne) 154 3007 334 Rondelet
Lava, Hard Vesuvian 166 8735 972 ..
Lava, Soft Vesuvian 107 2209 246 ..
Lava, Piperno (Pozzuoli) 162 8140 905 ..
Travertino, Old Roman 147 2297 255 ..
Travertino, Pæstum 141 3102 345 ..
Peperino, Roman 123 3135 347 ..
Tufa, Old Roman 78 797 89 ..
Tufa, Naples 82 718 80 ..
Hard brick 98 1851 206 ..
Soft ill-burnt brick 91 1200 133 ..
Mortar, lime, and sand, unground 102 423 47 ..
Ditto, ditto, ground 119 577 64 ..
Mortar, Pozzolano, of Rome and Naples, unground 92 503 56 ..
Ditto, ditto, ground 105 732 81 ..
Mortar, Old Roman (Campagna) 97 1047 105 ..
Mortar, Old French (Bastile) 94 753 84 ..
Plaster of Paris (mean) .. 500 55 Laisne

It appears, from the few experiments that have been made, that the resistance of stones, &c., to tension, varies from th to th the resistance of the same material to