TRANSVERSELY.
Material—Cast iron.
Bar of one inch squareDitto dittoHalf the above barBar of one inch square \through the diagonal JHalf the above barBar of 2 inches deep byinch thick on edgeHalf the above bar on edgeBar of S inches deep by §■inch thick on edgeHalf the bar, dittoBar 4inches by \ inchthickdo
Equilateral an §' leU Ptriangles,inch areainsection
Weight ofthe bars.
Distance ofbearings,ends loose.
lbs.
10
9
oz.
6
8
?e
*}
angle down
1 4
2 8
.half the first barhalf the secondbar
An inch bar, the end made 1fast - - j
An inch square bar-. Qne end made fast? the
. . ,,. . , " I weight being suspended at
A bar 2 inches deep the ° other at & 2 { J t8 inchesby | an inch thick from the bearion edge - - J °
9 8
9 5
9 15
lbs. avoirdu-pois requiredto break thebars describ-ed in the firstcolumn.
feet inches
3 0
7
11
7
2 8
1 4
2 8
1 4
2 8
Modulus of frac-
ture or lengthof a rod inchsquare in sectionof the materialequal in weightto the breakingweight.
Feet.
1
2
2
2
1
897
1086
.2320
851
1587
2185
4508
3588
6854
3979
1437
840
3059
1656
1173
283
539
259
304
651
238
445
624
1290
962
1839
1125
395
237
842
467
are formed, having for their base the upper side of the cube next the lever, theaction of which displaces the sides of the cubes, precisely as if a wedge hadoperated between them. I have preserved a number of the specimens, thesides of which, if continued, might cut the cubes in the direction of theirdiagonals.”
By referring to the column of the modulus of fracture, which is also ameasure of the compression at the vertex, or horizontal thrust of an arch, orthe limit of the radius curvature at that point, it will be seen, that an archbearing nothing but its own weight of cast iron (vertical casting) is limitedto a radius of curvature at the vertex 58040 feet in length = 4 miles nearly;of English oak, the radius of curvature at the vertex is limited to 10906feet = 2-A miles ; of Aberdeen granite, the radius of curvature is limited to9588 feet = l T 9 r miles. It will be observed from this, that the radius of cur-vature of an arch of oak supporting only its own weight, is greater-than thatof granite ; but it must not therefore be concluded that a less quantity of oakwill be required for an arch cceteris paribus than of granite, when a weight isto be borne. See Table of Examples.