STE
479
STR
Vv ]' , ' n S e xp e rimems were made on the transverse strength of8 c American red pine timber selected from the
folding employed in erecting the tubes.
Ion 6Se beams were exactly 12 inches square and 17 feetdistance between the bearings being 15 feet. They« B „ r . e broken by actual weight suspended on a scale from theen ‘>'e of the beams.
vJ"y timber from the butt end of the balk:—f 0ot fc 'ght of the beam, 5 cwt. 2 qrs. 5 lbs. or 36.51bs. per cubic
faking weight, 14.82 tons.
timber from the top of the balk :—
-eight of the beam, 5 cwt. 17 lbs, or, 33.91bs. per cubic foot.‘Baking weight, 13.24 tons.
es **lts of Experiments made with actual Weight on Mate-^als used in the Britannia Bridge, January, 1848.
^o. j
( Brickwork .)
lbs. per sq. in.
9-inch cube of cemented brickwork (Nowella nd Co.,) No. 1 (or best quality), weighinglbs., set between deal boards. Crushed
2 " Uh 19 tons cwt • 2 < l rs- 22 = 551.3
• 9-inch brickwork, No. 1 weighing 53 lbs.,
® et in cement. Crushed with 22 tons 3 cwt.
ft 0iS 17l bs. = 612.7
’ “• 9-inch brickwork, No. 3 weighing 52 lbs.,in cement. Crushed with 16 tons 8 cwt.
\ 4 9 rs . 8 lbs. . = 454.3
' 9^-inch brickwork, No. 4 weighing 55^ lbs.,
® et in cement. Crushed with 21 tons 14 cwt.
17 lbs. = 538.5
■ 9-inch brickwork, No. 4 weighing 54^ lbs.,
® et between boards. Crushed with 15 tons^ c 'vt. 12 lbs. = 417.
]$ Mean. 521.
*bpp o e> The three last cubes of common brick continued to<tl| t n the weight although cracked in all directions; they
Pieces when the load was removed. All the brick-
> ef 0j . e “ e gan to show irregular cracks a considerable time^ 11 gave way.
e n^erage weight supported by these bricks was 33.5\l, ,. er square foot, equal to a column 583.69 feet high ofOr ickwork.
• 0, o •
i43 lnC 1 cu ^ e re< ^ sandstone, weighing 1 lb.
1) i, 02 ' 5 set between boards (made quite dryv J'- eing kept in an inhabited room). Crushed
■ °'7 *o .8 tons 4 cwt. 19 lbs. = 2043.
j' “'inch sandstone, weighing 1 lb, 14 oz., setV 5 , Cetnent (moderately damp). Crushed with
\ 8 *on 8 3 cwt. 1 qr. 1 lb. = 128.5
8 "j n ch sandstone, weighing lib. 15^-oz.,v, vvin.’ n cement (made very wet). Crushed
\ 9_ g . 4 tons 7 cwt. 21 lbs. = 1085.
Set ' ln °b cube sandstone, weighing 18 lbs.,v o ln cement. Crushed with 63 tons 1 cwt.
\ lo 1 r s. 6 lbs. = 3924.8
Set cube sandstone, weighing 58^ lbs.,
W, 1 " cement (77^-tons were placed upon thisW a ° ut effect = 2042 lbs. per inch, which
as much as the machine would carry). -
^ Average crushing weight. 2185.
?V *°U8 6 san ^ stones gave way suddenly, and without anyCr &cking or warning. The 3-inch cubes appeared of
ordinary description ; the 6-inch was fine-grained, and appa-rently tough, and of superior quality. After fracture, theupper portion generally retained the form of an invertedsquare pyramid about 2high, and very symmetrical, thesides bulging away in pieces all round. The average weightof this material was 130 lbs. 10 oz. per cubic foot, or 17 feetper ton.
The average weight required to crush this sandstone is134 tons per square foot, equal to a column 2351 feet high ofsuch sandstone.
lbs. persq. in.
No. 11. 3-incli 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 was considerably crushed; but, upon removing theweight, about two-thirds of its area were found uninjured.
No. 12. 3-inch limestone, weighing 2 lbs. 9 oz., setbetween deal boards. Crushed with 32 tons6 cwt. 1 lb. = 8039.
This stone also began to crack and splinter externally with25 tons (or 6220 per inch), but ultimately bore as above.
No. 13. 3-inch limestone, weighing 2 lbs. 9 oz., setin deal boards. Crushed with 30tons 18 cwt.
3 qrs. 24 lbs. = 7702.6
No. 14. 3 separate inch cube limestone, arranged
in a triangle, weighing 4£ oz., set betweendeal boards. Crushed with 9 tons 7 cwt.
1 qr. 14 lbs. = 6995.3
All crushed simultaneously. -
Average. 7579.
7338.5
All the lime-stones formed perpendicular cracks and splin-ters a considerable time before they crushed. Weight of thematerial from above = 165 lbs. 5 oz. per cubic foot, or 13^feet per ton.
The weight required to crush this limestone is 471.15 tonsper square foot, equal to a column 6433 feet high of suchmaterial.
( Single Bricks of different qualities.)
No. 15. A single brick, No. 1 (Nowell and Co.),weighing 8 lbs., bedded flat in cement.
Crushed with 17 tons 19 cwt. 1 qr. 7 lbs. ... = 1022.No. 16. A single brick, No. 3. Crushed with
13 tons 11 cwt. 1 qr. 6 lbs. = 750.
No. 17. A single Birkenhead brick, 9 X 4^",weighing 7 lbs. 14 oz., bedded in cement.
Crushed with 32 tons 2 cwt. 17 lbs. = 1775.8
No. 18. A single Buckley mountain brick,
9-1" x 4£", weighing 9 lbs. 2 oz., bedded incement. Crushed with 40 tons 13 cwt. 15 lbs. = 2130.3
These last experiments not being on cubes, only serve forcomparisons among themselves. The bricks were completelycrushed into powder. The cement used in all the aboveexperiments invariably began to crack away round the edgesas soon as a very moderate weight was applied.
STRETCHED OUT, a term applied to a surface thatwill just cover a body, and is extended in such a mannerthat all its parts are in a plane, or may be made to coincidewith a plane.
STRETCHER, a term applied to bricks or stones soplaced in a wall that their longest side shall be parallel to theface of the wall; those bricks, on the contrary, which have