The spacing

Between the multiple elements that characterize and differentiate the first issue stamps in the various printing runs there is the horizontal spacing between the pieces. It's another detail that allows for a correct classification of the stamp type and of its composition.
At the beginning the average horizontal spacing between two pieces was around 2.5 mm and later on, probably to simplify the separation with the scissors made by the postal workers, it was increased to around 3.0 mm. The larger spacing was recovered by decreasing the group inter-space that went from 24 mm to around 14.5 mm (it was therefore shrunk even beyond the necessary...). More constant was instead the vertical spacing that was only slightly revisited going from 3.20 mm to around 3.0 mm. The stamps with the first spacing type are called with "narrow spacing" while the following ones with "large spacing".
I summarize here below the spacing type present for each value:

Stamp	Spacing
5 centesimi	Narrow
10 centesimi - handmade paper	Narrow
10 centesimi - macchine made paper	Large
15 centesimi - 1st type	Narrow
15 centesimi - 2nd type	Narrow
15 centesimi - 3rd type - handmade paper	Large
15 centesimi - 3rd type - macchine made paper	Large
15 centesimi - ribbed paper - 1st and 2nd type	Narrow
15 centesimi - 3rd type - laid paper	Large
30 centesimi - 1st type	Narrow
30 centesimi - 2nd type - handmade paper	Narrow & large
30 centesimi - 2nd type - machine made paper	Large
30 centesimi - 1st type - ribbed paper	Narrow
45 centesimi - 1st type	Narrow
45 centesimi - 2nd type - slate - handmade paper	Narrow
45 centesimi - 2nd type - blue - handmade paper	Large
45 centesimi - 2nd type - machine made paper	Large
45 centesimi - 1st type - ribbed paper	Narrow

Here below I show two beautiful couples, one of the 5 centesimi with narrow spacing (Fig. 1) and one of the 45 centesimi with large spacing (Fig. 2). The difference is quite visible even if we are dealing with only half millimeter.

Fig. 1: narrow spacing



Fig. 2: large spacing