ISSu.] LETTERS TO THE EDITOR. 233 



the wood at their lower parts. Soiuetiiues all the higher and lateral 

 branches, sometimes the tops of an entire group of trees, are struck. 

 The helix spirals often found on a riven oak show the tendency of 

 the electric current to follow the longitudinal direction of the cells 

 constituting the young wood. — I am, etc. Thundeebolt. 



WHAT IS THE MOST DULABLE STAKED 



TuiixHAM Gr.EEX, LoNDOX, ith Dec. 1SS4. 



CI IK, — I have seen in some of your back numbers inquiries 

 kj about the durability of stakes and posts below ground. Per- 

 haps the subject is not worn out yet, and you may be still inclined 

 to make room for a word or two about it. 



Three years and a half ago, I fixed up some poles to form an 

 arbour, with climbers trained o^'er them. This year, in November, 

 I removed the woodwork, as I wanted to extend my greenhouse 

 beyond it ; and I took occasion to observe the effect of the eartli 

 and moisture on the different descriptions of wood, which I noted 

 down at the time. The variety consisted of hazel, -poplar, birch, 

 alder, and oak. Only the poplar was painted ; the others were left in 

 their natural state. Above ground, they -were all sound and good ; 

 below, all gone, — but in different degrees. And, strange to say, 

 the alder was the least decayed. It was still in fibre, but softened, 

 and it cut clean with a sharp knife ; while all the others, not except- 

 ing the oak (a sapling of course, being only about two inches in 

 diameter, like the others), went to touchwood and crumbled to atoms 

 on applying a tool to them. The bark of the alder was also 

 pecrdiar. It could only be scraped or shaved off, not peeled, as it 

 seemed part of the wood itself ; while the oak and hazel bark was 

 loose, — part of it had already fallen, and the rest easily peeled oft', 

 leaving a kind of rust or brown pollen behind it, as if the wood or the 

 bark had already begun to moulder away there. In no case had 

 the decay extended above ground, and as tliey were trellised to- 

 gether, they would no doubt have lasted another year or two 

 witliout giving way. As it is, I have shortened them at the butt 

 by G inches (the depth they were ^^/n^JiScf/) out of 8 feet, giving 

 them a coat or two of paint, and they are as strong as ever, and 

 much better-looking, for use again. 



The only special fact worth noting in this description is, that 

 alder partly underground appears to have more durability ca:.teris 

 j)aribus than oak. I wonder have any others among your readers 

 observed tlie same thing ? — Sir, yours very obediently, K. B. 



