n. 视距计

[医] 动速测量器

[ noun ]
a theodolite designed for rapid measurements
<noun.artifact>

Tachymeter \Ta*chym"e*ter\, n. [Tachy- + -meter.]
1. (Surveying) An instrument, esp. a transit or theodolite
with stadia wires, for determining quickly the distances,
bearings, and elevations of distant objects.
[Webster 1913 Suppl.]

2. A speed indicator; a tachometer.
[Webster 1913 Suppl.]