A friend of mine came recently with a slice from their firewood cellar, at Baggensgatan in the Old Town of Stockholm, and asked if I could date it. The thin ring widths indicated that the wood was not too young.

Later, I found that the 60 innermost rings had a mean width of 2 mm, the outermost 152 rings had a mean width of 0.7 mm! Where can I buy that quality of wood today?

I've measured three radii from the "slice", available here as a STP01.rwl.


An analysis was run in CDendro with a collection of several members, each representing a mean value curve from an area in Sweden, Norway, Denmark, Estonia and Finland. The sample was selected as the reference and the analysis done as a Test Towards UNDATED Reference ("With condensed report" checked!) which gave these best matches:

                  T-    Over 
           Corr   Test   lap  Year 
all...     0.31   4.79   212  1619   based on 37 members 
BratPIr    0.56   6.79   101  1619   Mälardalen (Bråthen), questionable segments removed 
SödraDal   0.38   5.99   212  1619   SDalar 1 Södra Dalarna    PISY 
Gagnef-s   0.36   5.66   212  1619   Gagnef-Djura 
DALARNA    0.33   5.09   212  1619   Dalarna, Lunds universitet (EXTRATERR) 
9M45678    0.31   4.65   212  1353   Denmark (WestDK) Old version 
swed304S   0.34   4.53   164  1958   Tyresö, Sisshammar (SE Stockholm 5913 1821) Andreason PISY 1661-1910 
Saltsjob   0.29   4.37   212  1958   Saltsjöbaden 
..... 
Year numbers occurring more than once: 
 1619    7 
 1958    5 
 1755    2 

With the reference dated to 1958, there was no better match than corr-coeff = 0.34
So 1619 might be a good candidate! With the reference dated to 1619, the best matches were:

                    T-  Over 
           Corr   Test   lap 
all...     0.42   6.63   212   based on 5 members 
BratPIr    0.56   6.79   101   Mälardalen (Bråthen), questionable segments removed (1153-1904) 
SödraDal   0.38   5.99   212   SDalar 1 Södra Dalarna    PISY (1362-2005) 
Gagnef-s   0.36   5.66   212   Gagnef-Djura (1362-1831) 
DALARNA    0.33   5.09   212   Dalarna, Lunds universitet (EXTRATERR) (932-1888) 
SWED305B   0.31   4.14   169   Björbo, Dalarna (1451-2002) 

I.e. that tree actually grew between 1407 and 1619 (we can be very certain about that number!), though there may be some sapwood cut away, so the tree was cut some years after 1619. I.e. it is of the same time as the old Wasa ship!
We do not know from which house the wood originates, as old wood is often placed in containers when houses are repaired - and from there that wood is sometimes saved by people with a need of firewood.