This instrument resembles, to a certain degree, that known in the mechanical arts under the name of callipers, but it differs from it materially in other particulars, which render it more adapted to the uses for which it is designed. It is 0.18 in height, and from 0.12 to 14 in breadth. It can measure objects of the smallest dimensions as well as those of a diameter of 0.25, within one millimetre, which is sufficiently exact for all the practical purposes of horticulture. It is composed, like the ordinary compasses, of two brass legs, 0.10 in length, united by a rule joint, and which terminate in the curved steel branches, the points of woich meet accurately when the instrument is closed. A graduated quadrant is fixed by a screw to the right brass leg, passing through a fenestrum in the left leg, which can thus slide over this arc, until it is arrested at any point desired by means of a thumb-screw. The divisions on the quadrant indicate correctly the separation of the legs of the instrument, or rather the linear distance between their steel points. In order to measure a fruit, the legs are to be separated until the opposite points rub on its greatest diameter, the graduated scale then marks the extent of this separation, which is the diameter of the fruit.

In the same way its height can be measured.

It will readily be seen that, in addition to measuring the diameter of fruits, the diacarpometer may be applied to many other uses in horticulturs: one of which, as recommended by its ingenious inventor, M. Abel de la Faroe, member of the agricultural committee of Saless, is the determination of annular incisions in trees.

It will thus be perceived that the diacarpometer is not a fancy instrument, intended only for amateurs and dilettanti, but is destined to a practical and daily use in horticulture, to give more accuracy, grace, and elegance to the labours of the gardener, and at the same time afford more exact results than have hitherto been obtained in the exercise of this agreeable employment. - A. Remy, in Revue Horticultural

Diacarpometer Or Instrument For Measuring The Diam 50093