OF MATERIALS UNDER DIRECT PRESSURE.
367
between boards (made quite dry by being kept in aninhabited room).
Crushed with 8 tons 4 cwt. 0 qrs. 19 lbs.= 2043'
No. 7. 3-Inch Sandstone, weighing lib. 14 oz., set in cement(moderately damp).
Crushed with 5 tons 3 cwt. 1 qr. 1 lb.= 1285’
No. 8. 3-Inch Sandstone, weighing 1 lb. 15Joz., set in cement(made very wet).
Crushed with 4 tons 7 cwt. 0 qrs. 21 lbs.= 1085'
No. 9. 6-Inch Cube Sandstone, weighing 18 lbs., set in cement.
Crushed with 63 tons 1 cwt. 2 qrs. 6 lbs.= 3924’8
No. 10. 9^-Inch Cube Sandstone, weighing 58| lbs., set incement (77£ tons were placed upon this without effect,
= 2042 lbs. per inch, which was as much as themachine would carry).
Average crushing weight. 2185
All the sandstones gave way suddenly , and without anyprevious cracking or warning. The 3-inch cubes appearedof ordinary description ; the 6-inch was fine-grained, and ap-peared tough and of superior quality. After fracture the upperportion generally retained the form of an inverted square pyra-mid about 2-L" high, and very symmetrical, the sides bulgingaway in pieces all round. The average weight of this materialwas 130 lbs. 10 oz. per cube foot, or 17 feet per ton.
The average weight required to crush this sandstone is134 tons per square foot, equal to a column 2351 feet highof such sandstone.
(limestone.) Lbs. per
Sq. Inch.
No. 11. 3-Inch Cube Anglesey Limestone, weighing 2 lbs. 10 oz.set between boards.
Crushed with 26 tons 11 cwt. 3 qrs. 9 lbs.= 6618*
This stone formed numerous cracks and splinters all round, and wasconsidered crushed, but on removing the weight about two-thirds of its areawere found uninjured.