|On the instruments dimensions|
Within both the Virtual Museum's technical card and the on-line database's tool card the dimensions in centimeters (and inches) of each individual device are written. A photograph in fact is generally not able to express the actual size of an object, unless an appropriate background graduated reference scale is inserted.
The data amount needed to fully characterize an object from the dimensional point of view depends on the schematization assumed in relation to the aim with which these information are used. It is evident that to perform a reproduction of an instrument, three numbers such as length, depth and height are not sufficient, since in general also the simplest device not looks like a perfect parallelepiped, but has functional or decorative elements, protruding or recessed parts or curved elements which increase its complexity.
On the other hand, if you were to send a tool, it'd be enough just to know the minimum size "box" with very simple geometry (parallelepiped or cylinder) able to contain it. The sizes given in the cards precisely refer to this schematization according to two box types, a rectangular rectum parallelepiped (three numbers: width, depth, height) and a right cylinder (two numbers: base diameter, height).