Introduction Many Longines 13ZN dials have tachymeter scales. These scales can be centrally located or around the periphery of the dial. In this post, I will focus on peripheral tachymeter scales. I certainly do not claim to have included every variant but I hope to provide a relatively comprehensive selection. I have divided all variants shown below into two main groups: those with numbers that are exclusively parallel to the minute track, and those with numbers that are both parallel and perpendicular to the minute track. See diagram below for distinction between parallel and perpendicular. Part 1 - Parallel variants In my experience, parallel variants are somewhat less prevalent. The dial below is an uncommon variant and the watch is among the earliest 13ZN examples that I have come across. Both the font and style of this variant are reminiscent of enamel 13.33Z dials (see example below). The following dial is another uncommon variant. Like the dial above, it has the unique feature of multiple concentric levels. Again, I would describe the font and style as reminiscent of older designs. The two dials below are a more common variant. They tend to be found on later 13ZN examples than the variants above. The font used is of a more modern style. The variant below is also more common than the first two and generally appears on later 13ZN examples. This variant is also prevalent on 30CH dials (see example below). Part 2 - Perpendicular variants As alluded to above, perpendicular variants are arguably more typical. However, the dial below is an uncommon variant. The font is similar to those found on the early parallel variants. The two dials below are a relatively common variant. This variant appears in 13ZN examples from both the 1930's and 1940's. The font used is of a more modern style than the variant above. The two dials below are examples of possibly the most common variant. Similar to the variant above, this style appears across a wide range of serial numbers. The two dials below are another relatively common variant. As is evident, this variant is quite similar to the one above. I hope that this was of interest to some. Feel free to post examples of other variants. Disclaimer: Apart from the first diagram, I do not own any of these images.