(from dendron, a tree, and μέτρον, I measure), an instrument invented by Duncombe and Whittel, for which they obtained a patent, and so called from its use in measuring trees. It is fitted to a theodolite, and may be used either with or without it, as occasion requires.

The principal use of this instrument is for measuring the length and diameter of any tree, perpendicularly or obliquely to a horizontal plane, or in any situation of the plane on which it rests, or of any figure, whether regular or irregular, and also the length and diameter of the boughs, by mere inspection; and the inventors of it calculated tables, by the help of which the quantity of timber in a tree may be obtained without calculation or the use of the sliding rule.

an instrument for measuring distances by a single observation, proposed by Mr Pitt of Pendeford, near Wolverhampton. See Repertory of Arts, vol. i.