104
ROYAL ENGINEER'S OFFICE, Fremantle, W. A.
Table of the Strength of Swan River Timber “Jarra” showing the breaking weight in Cwts., the deflection in inches, the bearing being 12 fort in every experiment and the weight suspended from the middle of the spreimen.
23.2595.9
5 7.25 10 11.25 12 | 14 |15,25| 16 |17.25|19.25| 20 |23.25 25.25 27.25 30.2585.25|38.25|40.25|| 45
47
50 52 54
58
60 02
67
70 70
A
B
C
D
E
70
Line of
3
Cwt.
SCANTLING
IN INCHES.
2 x
2
16:
9 x 4
6
9 × 21
9 × 201
9 × 23
9 × 21
9
16
516 8
B
8
6
1
16
16
J. 1
THE HONGKONG GOVERNMENT GAZETTE, 11TH APRIL, 1863.
] [t
13.
JA
16
1 ?
10
J. 3.
16
1%
1
142
C
R
18 | 13 | 13 | 1 a
120.
.310
.25
3.
01
b
108.
.421
~ 16
1875
9
1
.25
16
16
16
10
12
16
.25
875
122
16
10
242 244 3
16
67.48
.421 335.73
282.75
04
21
344
.875
142 144
28212
3
21
216
.75
31
3
53 32.473 1208.6
161.
5
40.80] .541 261.08
.65
161.
.65
32 64
25.00
541 261,35
875
242.
.757 186.66|1.
188.5
1.
1.25
1.
-16.04
.757 180.7
75
129.5
1.
1.25
1.
1.25
18
18
15
1
14
1
::
16
1
112 1132 21
21
213
OF
~/16
14
142%
418
3
18
418
518
NOTE a.
b.
>>
C.---
This specimen was loaded at intervals during 15 days, 4 cwts. being added at each increase, it remained loaded six days, when the stay which prevented it from twisting broke and the jerk broke the specimen. This load was applied at intervals during two days, and remained loaded four days, when it broke with a fracture 3 feet long. This specimen was loaded at intervals during ten days, when it broke with a compound fracture 5 feet long.
The remaining specimens were loaded at once, one hundred weight being added at a time until the result was produced the fracture varying from 6 to 4 feet. The top line in this Table is the weight in Hundred weights and the figures below them in the same column shew the deflection in inches and sixteenths of inches of the several specimens at the respective weights, the last register of deflection being the breaking weight. COLUMN A gives the breaking weight of "Red Pine" (from Lea's Timber Tables) of the same scantling as the specimens of “Jarra.”
""
B gives the deflection of "Red Pine" at one fourth of the breaking weight from the same authority.
gives the breaking weight of "Red Pine" per square inch in section of these scantlings severally.
D gives the deflection of "Jarra" at one fourth of its breaking weight.
E gives the breaking weight of "Jarra" per square inch in section of the mean of these specimens,
The mean of eight specimens of 9,× 23 gives 57.25 cwts. as the breaking weight and two and a half inches as the actual deflection from the full load and .625 as the deflection loaded with one fourth of its breaking weight, Red Pine being 67.48 cwt. breaking weight and 421 deflection, shewing that “Jarra" is to "Red Pine" as 11 to 13 in this scantling. The mean of eight specimens of 5" × 2′′ gives 11.562 cwt. as the breaking weight and 44 inches as the actual deflection from the full load and 1.47 inches as the deflection loaded with one fourth of its breaking weight. Red Pine" being 16.64 cwt. breaking weight and .757 inches deflection, showing that "Jarra" is to "Red Pine" as 23 to 33 in this scuntling. The above specimens are not picked for their superior quality, but taken at random from a pile of sawn timber and being of fair average quality such as would be passed in general work as good timber, may therefore be taken as a fair standard for general purposes in practice. Of course these specimens would bear double the reported load for breaking weight if the load were uniformly distributed over the whole length of the specimen one fourth of the breaking weight being the load allowed in practice by common consent of most practical Engineers on the subject. REMARK.—From the above results it is evident that "Jarra" is inferior to "Red Pine" in transverse strength, but it is superior for many purposes as being proof against the attacks of the White Ant so common in tropical climates and destructive to almost every kind of wood work. It also resists the Teredo Navalis or Sea Worm and being very durable both in and out of water and not affected at the water's edge or between wind and water to the same extent as other timber in general use, it is therefore invaluable for all kinds of Wharfing and Waterworks.
A true copy,
ROBT. KING.
(Signed) JAMES MANNING, R.E., Clerk of Works.
16
1
16
6
tatatatata૭૭૪૭૨૭૨૩૦૨
X X X X X X X X X X X X X X X X
IINNNA SALO O 10 10 10 10
3
*sical
3
5 03
3%
5542
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