381/380
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| Ratio | 381/380 |
| Subgroup monzo | 2.3.5.19.127 [-2 1 -1 -1 1⟩ |
| Size in cents | 4.549895¢ |
| Name | five feet comma |
| Color name | 127o19ug1 |
| FJS name | [math]\text{d2}^{127}_{5,19}[/math] |
| Special properties | superparticular, reduced |
| Tenney height (log2 nd) | 17.1435 |
| Weil height (log2 max(n, d)) | 17.1473 |
| Wilson height (sopfr (nd)) | 158 |
| Harmonic entropy (Shannon, [math]\sqrt{nd}[/math]) |
~1.39107 bits |
| Comma size | small |
| open this interval in xen-calc | |
381/380, the five feet comma, is the 127-limit ratio that is the difference between the 127/64 and 95/48.
Real life
It represents the difference between 1524 mm railway gauge and the 1520 mm, which were used interchangeably in the areas of the former Soviet Union and Russian Empire. Such an approach did result in wear of the train undercarriage, but it wasn't significant enough of a difference and it was therefore applied for a certain time.
Links
- Wikipedia Contributors, 5 ft and 1520 mm gauge railways.