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The Pamphlet Collection of Sir Robert Stout: Volume 66

Strength of New Zealand Timbers

Strength of New Zealand Timbers.

The following table gives the results of experiments, extending over a period of some years, on the strength of the principal timbers of the colony :— page 13
Results of Experiments on New Zealand Timbers. [The dimensions of the specimens were 1 inch square and 12 inches long.]
No. Native Names in Alphabetical Order. Specific Gravity. Weight of a Cubic Foot. Greatest Weight carried with Unimpaired Elasticity. Transverse Strength.
lb. lb. lb.
1 Hinau, or Pokaka (Elœocarpus dentatus) .562 33.03 94.0 125.0
2 Kahika, supposed white-pine .502 31.28 57.3 77.5
3 Kahikatea, white-pine (Podocarpus dacrydioides) .488 30.43 57.9 106.0
4 Kauri (Dammara australis) .623 38.96 97.0 165.5
5 Kawaka (Libocedrus doniana) .637 39.69 75.0 120.0
6 Kohekohe (Dysoxylum spectabile) .678 42.25 92.0 117.4
7 Kowhai (Sophora tetraptera var. grandiflora) .884 55.11 98.0 207.5
8 Maire, black maire (Olea cunninghamii 1.159 72.29 193.0 314.2
9 Maire-tawhake (Eugenia maire) .790 49.24 106.0 179.7
10 Mako (Aristotelia racemosa) .593 33.62 62.0 122.0
11 Manoao (Dacrydium colensoi) .788 49.10 200.0 230.0
12 Mangi, or mangeao (Tetranthera calicaris) .621 38.70 109.0 137.8
13 Manuka (Leptospermum ericoides) .943 59.00 115.0 239.0
14 Mapau, red mapau, or red-birch (Myrsine urvillei) .991 61.82 92.0 192.4
15 Matipo-tarata (Pittosporum tenuifolium) .955 60.14 125.0 243.0
16 Matai (Podocarpus spicata) .787 49.07 133.0 197.2
17 Miro (Podocarpus ferruginea) .658 40.79 103.0 190.0
18 Puriri (Vitex littoralis) .959 59.50 175.0 223.0
19 Rata, ironwood (Metrosideros lucida) 1.045 65.13 93.0 196.0
20 Rewarewa (Knightia excelsa) .785 48.92 93.0 161.0
21 Rimu, red pine (Dacrydium cupressinum) .563 36.94 92.8 140.2
22 Taraire (Nesodaphne taraire) .888 55.34 99.6 112.3
23 Tawa (Nesodaphne tawa) .761 47.45 142.4 205.5
24 Tawiri-kohukohu, white mapau (Carpodotus scrratus) .822 51.24 80.0 177.6
25 Titoki (Alectryon excelsum) .916 57.10 116.0 248.0
26 Totara (Podocarpus totara) .559 35.17 77.0 133.6.
27 Tawai, red-birch (Fagus menziesii) .626 38.99 73.6 158.2
28 Tawai, black-birch (Fagus fusca) .780 48.62 108.8 202.5
29 Whawhako (see also Maire) (Eugenia maire) .637 39.63 75.0 120.0
30 Whau (Entelea arborescens) .187 11.76 13.0 32.0

The experiments were conducted in the following manner: A pressure of 50lb. was applied for two minutes (as measured by a sand-glass), and the sample was then released; 75lb. was then applied for the same time, and then 100lb., and so on, increasing by 25lb. each time. Each time the sample was released the point on the deflection scale to which, it returned was read, and when it came to be notably under the original reading it was allowed to remain unloaded for two minutes, to see whether it would in time recover itself. Then the pressure was gradually increased, without being removed, until the specimen broke.

A particular description of forty-four of the principal forest-trees will be found in the appendix.