ON FELLINC AND SEASONING OAK TIMBER. 127 



TIMBER. 



The durability of limber in all constructions, is a matter of great 

 importance, and has led to many experiments in order to ascertain 

 the most proper time of the year in which it should be felled. 

 There are still various opinions respecting the proper season. If 

 any of our readers have had any experience in these things and 

 can state facts, we should be very much obliged to them for any 

 communications on the subject. The following on " Felling and 

 Seasoning Oak Timber," is extracted from the London Mecahnics^ 

 Magazine. 



Gentlemen, — As it must be acknowledged that every thing tend- 

 ing to improve the art of ship-building, either in the theory or prac- 

 tice, is of primary importance in a maratime country, I have ven- 

 tured to send a few of my ideas on the subject of felling and season- 

 ing oak timber : if they should not prove founded on a just view 

 of the matter, they will, perhaps, elicit from some of your corres- 

 pondents information that I have no doubt will prove valuable to 

 many of your readers. 



1st. Oak timber is generally felled for naval purposes about 

 May, when the sap is rising in the tree ; and this time is chosen on 

 account of the bark stripping easier. This is very injudicious, 

 however, as regards the timber ; for the capillary tubes being full 

 of moisture, the tree contains a greater quantity than would be the 

 case if felled in the winter, which is the time I should recommend, 

 and which, some years ago, was the practice. I believe that when 

 winter-felled timber was used for naval purposes, very little, if any 

 thing, was ever heard about the dry-rot. It is my opinion that 

 winter-felled timber is of a better texture than spring felled, as the 

 vessels are not distended ; and the cold causes a contraction of the 

 fibres, which in the Spring are dilated with the heat and sap. Now, 

 my idea of one cause of the dry-rot is this, — that in in Spring-felled 

 timber, the moisture it contains, when evaporated, leaves the se- 

 cretion in the vessels, which, when it meets with a peculiar state 

 of atmosphere, undergoes a fermentation, and causes ultimately a 

 decomposition of the timber. Another thing which I think has 

 tended much to hasten the decay of our ships, has been the indis- 

 criminate use of foreign timber, particularly Quebec oak, which 

 has been used in his Majesty's dock-yards for all purposes on board 

 of ships where a straight timber was applicable. Now, it has 

 struck me several times, whether by thus bringing timber of dif- 

 ferent species and countries (for they have likewise used oak fronj 

 the Adriatic) in contact with each other, a chemical action may 

 not arise from the difference in the juices of the timber, I'avorabic 

 to decomposition, or what we call the dry-rot. I think it proba- 

 ble some such action might take place ; but I am not chemist 

 enough to follow up experiment? on (hif subject, nor have I eithej 

 time or opportunity. 



