Article image
Article image
Article image
Article image
This article displays in one automatically-generated column. View the full page to see article in its original form.

How to Select Good Timber.

Professor Rankine says :—"There are certain appearances which are characteristic of strong and durable timber, to what class soever it belongs. 1. In the same species of timber that specimen will in general be the strongest and most durable which has grown the slowest, as shown by the narrowness of the' annual rings. 2. The cellular tissue, as seen, in the medullary rays (wheix visible), should be hard arid compact. 3. The vascular or fibrous tissues should adhere firmly together, and should show no 'woolliness at a freshly cut surface, nor should it clog the teeth of the saw with loose fibres. 4. If the wood is coloured, darkness of colour is in general a sign of strength and durability. 5. The freshly-cut surface of the wood should be firm and shining, and should have somewhat of a translucent appearance. A dull, chulky appearance is a sign of bad timber. 6. In a wood of a given species, the heaviest .specimens are in general the strongest and most lasting. 7. Among resinous woods,.those which have less resin in their pores, and jiraoii" non-resinous woods, those which have least sap or gum in them, are in general the strongest and most lasting. 8. It is stated by some authors that in fir wo* (1 that which has the most sap wood, and in hardwood that which has the least, i.s the most durable ; but the universality of this law is doubtful. Timber should be free from such blemish ss as clefts or cracks radiating from the centre; "cupshakes " or cracks which particularly separate one annual layer from another ; V "upsets," where tie fibres have been crippled by compression ; V " ringalls," or wounds in a layer of the wood which have been covered and concealed by the growoh of subsequent layers over them.

This article text was automatically generated and may include errors. View the full page to see article in its original form.
Permanent link to this item

https://paperspast.natlib.govt.nz/newspapers/AG18900910.2.7

Bibliographic details

How to Select Good Timber., Ashburton Guardian, Volume VII, Issue 2514, 10 September 1890

Word Count
306

How to Select Good Timber. Ashburton Guardian, Volume VII, Issue 2514, 10 September 1890

Working