Since all measuring is a comparing, the concept of time is based on the comparison of "singular events, which are available to our recollection, according to the, not further to be analyzed, criterion 'earlier' and 'later' " (quoted from Einstein's 'Basic Principles of the Theory of Relativity'). Thus we achieve - by an original achievement of the cognitive and perceptual apparatus: its comparing remembering - the chronological dimension of experience and the concept of time as order of consecutive events (Leibniz). The ability of recollection and the ability of determination of contents of memory according to the criterion of 'earlier' and 'later' are the pre-condition of the capability of experiencing all qualities which are temporal. Yes, the impressions of movement and temporality are indeed only created by the comparing memory, whereas the senses can only produce snap-shots. Without the mental conjunction of these snap-shots there would thus be nor time, nor movement, nor language and nor music, but only single sounds and tunes without sense. How can therefore anyone believe that there is no such thing as the role of the observer?! Without him there wouldn't even be tunes, but only air vibrations, such as there would be no light and no images without the eyes etc.
Seen metrological the duration is the difference of two points in time, such as the length is the difference of two points in space. The standard watch placed in the coordinate origin or anywhere else does not 'measure' but only provides - like any of the other coordinates - measurement points (in this case points in time), which have been defined by humans. Therefore I consider the much-vaunted unity of the temporal and the spatial coordinate merely and only in this this decisive function, in which points in space are given us side by side, whereas points in time are provided consecutively. A difference which is irrevocable and becomes quite obvious in the digital display of time with the constant change of the points of time, which are indeed measuring points for the duration, which can in turn be measured with their help.