While at first glance the sub-dials look fairly straightforward, a second look will uncover some strangeness. At nine o’clock we have the usual running seconds and at six we have the 12-hour measure, but look at the namesake “big eye” register at three. The BigEye’s three o’clock register is a 30-minute scale, but the large hash marks fall every three minutes, not every five like you might assume. As you look closer, you realize it's just strange enough to look balanced while compromising the speed at which you can read the measure (at least initially). The three-minute hashing is likely the result of a specific need presented for the original model. Other vintage chronographs have similar specific intervals to help pilots time standard turns (generally two minutes) or even to help time long distance phone calls.