most recent measurement

Data to 23 June 2015, shrinkage winter & spring

8.4 m girth veteran tree in Middleton-on-the-Hill [Thanks to owner Robin!]

3/3/13: Attached brass lugs with stainless screws to the bark to support tape

Ensured lugs all lie in a horizontal plane

Positioned so the tape doesn’t touch the bark, sliding evenly over brass lugs

Tape should end up perfectly horizontal and only in contact with brass lugs

One end of the tape is anchored

The other end is attached to an anchored spring

The tape overlaps itself and can move freely as tree diameter expands..

..and becomes a self-measuring vernier device

13/03/2013: Subtract the two aligned tape readings: G=8453.6mm

18/04/2013: G=8451.7mm [1.9mm contraction: real or system bedding in?]

1/08/2013: G=8459.5 mm, 7.8 mm girth increment from previous (75 μm/day mean)

26/08/2013: G=8461.1 mm, 1.6 mm girth increment from previous (64 μm/day mean)

19/10/2013: G=8464.2 mm, 3.1 mm girth increment from previous (57 μm/day mean)